Branching Out Wood

Modern Functional Home Decor by David Wertheimer

Moisture & Wood Movement

David WertheimerComment

Continuing with the theme of wood engineering topics - the last post was about how to avoid sagging shelves - here I’ll touch on the basics of how moisture effects wood, and what to do to minimize that impact.

No, I’m not talking about wood decay and rot that the homeowners among us suffer in our siding and patios. That’s “simply” avoided by keeping that fine furniture dry. Rather, wood expands and contracts with changes in the atmospheric humidity. In Understanding Wood, Bruce Hoadley estimates that the seasonal change in humidity in the average U.S. climate for a two-story wood-framed house can change the height of a house by 3/4”!

But for many smaller “products”, the dimensional changes might be imperceptible either in absolute size or even in relative size. Nonetheless, even imperceptible changes can tear a beautiful piece of furniture apart if it’s not well designed to account for that movement; this earlier post on veneering showed one such picture. Or you may have noticed the impact with the drawer or door that sticks in summer but moves freely in winter.

In short, wood moisture content depends on the humidity. And wood size depends on wood moisture content. This can be a long and complicated topic, but I’ll boil it down to a few key points, and a handy online calculator!

Background in Layman’s Terms

Trees are collections of very long cells. When the tree is growing, those cells have water in them, and the cell walls also have water. The weight of water in a species in comparison to the completely dry version is called the moisture content (MC) - for instance, a board weighing 20# when freshly cut may only weigh 12# after it is fully dry, which yields a moisture content of 8# / 12# = 67%. Hardwoods have moisture content from 60% - 100%, but can range from 40% to 160% depending on species and where in the tree is being measured.

EMC vs RH.png

Wood bought from the lumberyard is typically dried - whether in a fast process in a kiln or more gradually by exposure to atmospheric air over years - to a moisture content level of 8-14%. That removes all of the water inside the cells, but leaves some water between the cells. However, the wood is gradually reacting with the environment, absorbing or releasing water. Though it differs slightly by species and a few other attributes, there is a relationship between relative humidity (how much “free” water is in the air) and the “equilibrium” moisture content (EMC) of the wood - that is, the moisture content at which the wood will not absorb or release more moisture.

But let’s back up for a moment - where is this moisture stored? Well, it’s stored where there already is some remaining moisture, in the cell walls. And because those cells are really long along the direction the tree grows, the effect of adding or removing water is somewhat akin to raking up autumn leaves with a steel-tined rake: it may get a little wider as leaves push the tines apart, but it doesn’t really get any longer.

Similarly, wood expands in the radial and tangential directions, but not really much in the longitudinal direction. In fact, that “3/4” inch” that a wood-framed house might grow or shrink in height isn’t at all because of the height of the vertical framing members, but due almost solely to roughly 38” thick of joists, top plates, sole plates, and subflooring in a two-story structure; a typical 8’ tall 2x4 installed might shrink only 1/16th of an inch even from a “green” fully saturated state to average 8% MC - so this direction of movement is insignificant and typically ignored in movement calculations and construction considerations.

So there’s a difference in shrinkage between the horizontal axes of the tree (which we need to be concerned about) and the vertical axis of the tree (which we can ignore). In fact, its a bit more nuanced: the expansion is larger in the tangential direction than in the radial direction. This is thought to be because of internal structures in the wood, but regardless this difference can be a relatively modest 1.4x in black walnut, or as much as 3.0x in California laurel.

How do you know if you have radial or tangential axis on the face of a board - or both? Though sometimes you may know from how the board was initially cut from the log, there is apparently some confusion among the terms quartersawn and riftsawn. So the best way to tell is to look at the board itself, observing how the growth rings cross the surface or the end.

Acknowledging that these terms might be somewhat inconsistent among different sources, in the diagram here, Plain Sawn boards will exhibit tangential shrinkage; Quarter Sawn primarily radial shrinkage (and so the most dimensionally stable); and Rift Sawn somewhere between the two.

Acknowledging that these terms might be somewhat inconsistent among different sources, in the diagram here, Plain Sawn boards will exhibit tangential shrinkage; Quarter Sawn primarily radial shrinkage (and so the most dimensionally stable); and Rift Sawn somewhere between the two.

So How Much Does it Expand & Contract?

How much wood moves depends on the seasonal fluctuation in relative humidity of the environment the wood is in, the wood type, and which axis of wood (tangential or radial) we are focusing on. You can find tables of tangential shrinkage (St) and radial shrinkage (Sr) percentages, such as here or in the Wood Database; these are the % shrinkage in that dimension from fully saturated to oven dry (i.e.: 0% MC). However, as shrinkage does not occur as the cell cavities dry out - shrinkage only occurs as the cell walls dry - and the cell cavities are empty only at approximately 28% moisture content, this is essentially the percent shrinkage in that direction as the wood changes from roughly 28% MC to 0% MC. And just to introduce a little more terminology, that 28% is called the “fiber saturation point”, or fsp.

We can roughly approximate* that shrinkage as linear as the MC of the wood changes. So we now need to just know the seasonal variation in relative humidity, use that to get to the seasonal variation in EMC. The equation is: width * shrinkage % * (delta EMC / fsp). Just to aid in intuition, the term (delta EMC / fsp) is essentially what fraction of the total possible range over which the loss in moisture content causes shrinkage is actually experienced by the board.

Putting it together in an example, the shrinkage of a 9” wide plain sawn yellow birch board from summer to winter is:

  • Width: 9”

  • Shrinkage percentage: plain sawn implies we should use tangential shrinkage percent; for yellow birch St is 9.2%

  • Delta EMC (equilibrium moisture content): this depends on the change in relative humidity in the region; fortunately, the USDA Forestry Products Lab has put together a map to aid here, reproduced below. For the San Francisco Bay Area, we should use 8% in January to 13% in July, for a delta of 5%. Some parts of the country have a range of as small as 1%; others experience a range as great as 6%. And if a piece might be taken around the US (or the world), it should be able to handle a range of 9%.

  • fsp: varies slightly between species, but 28% is generally a good-enough value to use for hardwoods

usda foresty products lab map.jpg

Putting it all together, that 9” poplar board in summer will get narrower by 9” * 9.2% * 5% / 28% = 0.148” in winter. That’s 1.6%, or nearly 5/32”.

* This approximation has an error of about 5%, which is small enough to be good for almost all applications, but when real precision is needed, refer to a more complex formula in Chapter 6 of Understanding Wood. And I’ve skipped over a few other details, such as the assumption that the board you’re working with is already at the EMC, and the EMC of your environment falls within the EMC of the environment where the piece will live. But hey, in a short blog post, some concessions must be made.

The Shrinkulator

Oy vey. That’s a lot to think of. Well, fortunately here there’s a handy online calculator that automatically pulls up the right data for different wood species and does the calculation. You still need to figure out where on the map you are (or the finished piece will be), and which dimension is radial or tangential. But the rest is done for you. Check out the Shrinkulator here.


So What?

Wood moves - so what? Well, a few examples are given at the top: sticking door, or the split coffee table. But there are two general potential problems from this movement:

  • The actual dimensional change

  • The uneven change in surfaces


Anyone who has done a wood floor - whether solid hardwood or engineered - has heard that the materials must be delivered and left onsite to “breathe” for a few days before installation; this is to acclimatize the planks to the on-site humidity so that there is less sideways movement that would open up gaps or cause buckling. This movement in floors is also less problematic in narrower planks as the more frequent gaps allow for a little more expansion or allow gaps to be spread amongst more lines, making them less visible. This flooring contractor highlights six common hardwood floor problems, and five of them are caused by movement-related moisture before, during, or after installation.

Or the uneven movement in a joint can cause problems as well. While just about every piece of furniture mates different faces of wood together, two common joint and construction techniques highlight the potential issues here:

Mortise & tenon joinery: Common in chairs, doors, and lots of furniture, a rectangular or round tenon fits snugly into a mating slot or hole cut for the mortise. If this is very snug when the wood is drier, say in winter, it’s attempt to expand in summer will be constrained by the lack of movement of the mortise (as that mortise will not grow in height with a change in humidity). This constrained expansion may deform the tenon so that, in winter when it shrinks again, it breaks the glue line and draws away from the earlier tight fit.

Mortise & tenon joinery

Mortise & tenon joinery

Rail & stile panel door

Rail & stile panel door

Rail & stile panel doors: Doors - for your kitchen cabinet or for your front door - may be of a rail and stile construction technique with solid wood panels. In short, the rail and stile form a channelled frame into which the panel can be inserted; a beginner woodworker may cut the panel to fit snugly in the channel. If the panel fits snugly in winter, as it expands in summer, it will burst or crack the frame. Or if the panel fits snugly in summer (and is then painted or finished after assembly), as it shrinks in winter, unfinished edges of the panel will start to show along the border of the panel.

As an interesting aside, wood movement is the reason plywood always has odd numbers of plies (or layers). Each ply is placed perpendicular to the previous one and would exert force on the face along the direction of the larger movement. An odd number allows those forces to cancel each other out.

There are countless other ways that movement can be a problem. For a piece to last for generations, a good woodworker will need to take movement into account in their craft.

How to Manage Movement?

Bruce Hoadley outlines five basic approaches in Understanding Wood: preshrinking, control moisture, mechanical restraint, chemical stabilization, and good design. While each of these is a book (or several) in itself, I’ll touch on them briefly here:

Preshrinking: Don’t work with green (freshly cut undried) wood! Green wood is useful in some circumstances - bending for instance. Typically, however, if you’re buying lumber from Lowes or from a specialty lumber store, it comes pre-dried, whether by kiln or air. But also - as the examples of hardwood floor issues above highlight - the wood may need to further acclimatize to your specific environment, particularly if its been stored outside, perhaps not sheltered from the elements.

Control moisture: Unless the piece is museum grade, you’re probably not going to keep it in a hermetically sealed environmentally controlled box. But you can do a lot to retard moisture exchange with the environment, reducing the extremes in moisture content the piece would achieve at the shorter-duration extremes of humidity we might experience environmentally, by the good application of a finish. Different types of finishes vary in their ability here, so do a little research. And - if it you’re not a museum - you can be mindful of the humidity you’re exposing the piece do, and exert some environmental controls (humidifier, dehumidifier) at the extremes which aren’t just good for your furniture, but also your comfort.

Mechanical restraint: Steel or plastics bolted to the wood can help restrain the wood - but depending on how much the wood needs to move, this could actually bow the wood between the bolts, bend plastics, or rip the bolts out! This technique is more commonly associated with plywood, where plies with perpendicular grain orientation are glued to each other to form a thicker panel. Douglas fir, for example, has tangential shrinkage of around 7.7% and longitudinal shrinkage of 0.1%; a plywood panel constructed of perpendicular plies of this has shrinkage (along both dimensions) of 0.5%, practically eliminating movement considerations.

Though plywood is often thought of as an ugly building material, there are beautiful architectural grade hardwood-veneered plywoods out there, far less expensive (and stabler and easier to work with and better for the environment) than the corresponding amount of hardwood. Just for rough numbers, in 2019, you can get a 4x8 3/4” sheet of a) construction-grade plywood for $30; b) casework-grade oak or maple plywood for $60; or c) architectural-grade walnut plywood for $250. With architectural grade, the veneers are bookmatched, consecutive, and defect free.

Chemical stabilization: Polyethylene glycol (PEG) or wood plastic composite (WPC) are two chemical approaches to stabilizing wood, though only the first is somewhat accessible to the small-shop woodworker. PEG essentially replaces the moisture in a green or fully-saturated board with a polymer of automobile antifreeze which does not evaporate, keeping the wood at its saturated dimension. I’ll confess I have no experience with either approach so will direct you to a google search to learn more!

Good design: This is where we often have the most control, between material selection, joint design and grain direction in the mating pieces, dimensional adjustments you can make (which may or may not be visible in the finished product), etc.

For a rail and stile cabinet door, for instance, a panel made of plywood won’t cause problems. Or if the design and profiles demand solid wood, a) sizing the panel small enough to allow for expansion without cracking the frame, b) finishing the panel before final assembly, and c) gluing the panel only in the center of the top & bottom rails can eliminate the problem; that’s how it’s been done for hundreds of years before the invention of plywood!

Mortise Example.png

For a mortise & tenon joint, splitting a round tenon allows for a fracture line to occur inside the wood rather than at the glue line; or redesigning the joint to allow for two smaller-width tenons rather than one wider tenon makes the joint stronger in multiple ways, including halving the amount of expansion a single mortise has to accommodate.

Also, as the tangential face expands faster than the radial face, which expands faster than the longitudinal direction - flipping the boards, where possible, so that the rates of expansion are most closely aligned helps. In this diagram, we would ideally want the mortises cut in the tangential face and the horizontal board with the tenons to have the tangential face on the side. That way, the movement left-to-right is identical (if the boards are of the same material). And additionally, the vertical movement of the tenons is the smaller tangential expansion, to more closely align with the non-movement in the longitudinal axis of the vertical direction of the mortises.

For something like a solid wood countertop or tabletop anchored to a steel or composite frame - such as a hanging vanity in a bathroom - you would want to screw in the back solidly, but allow for horizontal movement by creating oval slots for the holes along the side. A 24” deep maple countertop may shift as much as 3/8” along its tangential axis. Or - if you don’t have an easy way to create oval slots in steel, just drill larger holes and use washers for the screws.

This is just a scratching the surface of good design for wood movement, and I’m only a novice here. But hopefully this has gotten you thinking about some of the considerations, either as a woodworker yourself, or in better knowing what to ask about or the language to use in working with a fine craftsmen in the field.

How to Avoid Sagging Shelving

David WertheimerComment

Most of the smaller stuff I build is not “structural”, nor does it use a lot of material. But the bigger pieces - from built-ins to free-standing furniture - has to hold up to its own weight as well as years of use (and abuse).

How do we make sure those shelves don’t sag, or the floating countertop is solid? In this first post I’ll share pointers to several useful calculators, and touch on good guidelines and a few techniques to avoid finding yourself with a beautifully crafted piece of furniture that, under duress, starts looking like this!


How Much Sag is Too Much

You will probably notice deflection far before it gets to the sorry state of that coffee table! 1/32″ (0.03″) per running foot, or 3/32″ (0.09″) for a 3′ wide bookshelf or table, is typically visible.  And over many years, the sag of a shelf tends to increase by as much as 50% as it is stressed repeatedly in the same direction. So a good target for initial allowable sag is 0.02″ per foot or less.

Don’t Worry About Small Shelves

Many cabinet designs call for the flexibility of adjustable shelves. Unfortunately, however, adjustable shelves are more prone to sagging than fixed shelves, as anyone who has loaded a cheap Ikea bookshelf with all of their college textbooks can attest. This is a consequence of many factors in that $50 hand-me-down bookcase. But with a bit more planning and design consideration (and better materials), sagging can be wholly avoided.

However, for “small” shelves, sag is not really a problem and one can just ignore considerations of sag for typical loads. What’s “small”? The most frequently used quality materials for custom-built wood shelves are 3/4” thick plywood, poplar, or pine; definitely avoid the melamine-laminated composite shelving and MDF. And a typical shelf load to plan for is 20-40# per foot - libraries often plan for 35#.

A 30” wide adjustable shelf that is 10” deep, made of any of these three (plywood, poplar, pine) materials, will have an acceptable sag for a load of up to 35# per foot, or about 90# for the entire shelf. Make it of poplar - the stiffest of those three materials - and you can make a narrower adjustable shelf, down to about 8”, still without any problems. Deeper or shorter shelves? Or anticipating less weight? Sag definitely won’t be a problem for those small adjustable shelves.

Narrower shelves aren’t as strong, however. But fortunately, as you get narrower, it’s less likely that you’ll get to 35# per foot. A 6” deep adjustable shelf will probably not get loaded more than about 20# per foot - made of any of those materials, a 30” span would still be fine.

Of course, if you’re loading your shelves like that coffee table above, all bets are off!

The Sagulator

Wood Bin’s Sagulator wood sag calculator

Wood Bin’s Sagulator wood sag calculator

But - what if the design calls for something outside these “small” shelf guidelines? Higher weight capacity, or longer or narrower shelves? Then, it’s time to break out a calculator. But don’t worry - these are online calculations that hide the messy math, at least to start out with!

I’ve come across a few calculators online, but the Sagulator seems to be the best one so far for ease of use, flexibility, and options that allow for common solutions that woodworkers use to counteract sagging shelves. Select the material, enter a few numbers, and voila, it estimates the total and per foot sag, and even makes a judgement call, summarizing the results as one of Excessive, Borderline, or Acceptable.

Counteracting Sag

If your design sags too much, there are a few simple solutions, and a few more involved design changes. Let’s assume, however, that changing the size of the shelf, and how much load or weight you need it to support, is not an option.

For the examples below to give a sense of how much each design change can help, let’s focus on a 10” deep shelf, made of 3/4” thick plywood shelf. And let’s assume a typical 30# per linear foot load. Then we can find the maximum width shelf that will give an initial sag of 0.02” per foot.

Different Material

Some materials are just stiffer than others. Of the three most common for basic shelving - poplar is the stiffest, with pine and plywood just slightly less stiff (or, in engineering-speak, having a lower modulus of elasticity). However, switching to even less elastic (and more expensive) oak could push your design into safe territory; if the shelves will be painted, the material choice is almost irrelevant except for cost (and availability).

  • Pine (spruce): 28”

  • Plywood (fir): 28”

  • Poplar: 28”

  • Oak: 32”

If budget is no barrier, a beautiful hardwood like purpleheart is even stiffer, and could get you a 35” wide shelf, but that would be a very unconventional (and wasteful) use of that expensive wood!

Thicker Materials

Though Lowes or Home Depot only carries boards in 3/4” thickness, and plywood thicker than 3/4” is not very common, you can usually find thicker materials at a specialty lumber store. If you go to 1” thick material instead of 3/4”, that gets you another 10” or so of width.

  • Pine (spruce): 38”

  • Plywood (fir): 38”

  • Poplar: 41”

  • Oak: 42”

Edging Strip

Cosmetic edging strip

Cosmetic edging strip

An edging strip - typically, a solid piece of wood - can be fastened to the front edge of a shelf. Occasionally, this may be strictly a cosmetic element, such as that applied to the sides of a plywood shelf in order to “finish” the edge. If it’s the strip is no thicker than the shelf itself, it doesn’t really add any strength to the shelf.

However, when made thicker / taller, it often helps the shelves blend in more seamlessly to the rest of the cabinet system and show more heft and mass. The edging strip can be of the same material or a different material - often the shelf will be a dimensionally stable and inexpensive plywood, and the strip might be a slightly more expensive solid wood like poplar. See styles #1 & #2 in the diagram below for examples of a recessed edging strip and flush edging strip.

And that edging strip also need not have just a simple rectangular shape; it could be rounded, have a beaded profile, or… the imagination (and available router bits) is the limit.

That adjustable plywood shelf that sags 0.02”/foot when 28” long could be extended to:

  • 34” with 3/4” thick by 1-1/2” tall poplar edging strip (most common size and material for paint grade)

  • 35” with same strip made of oak instead

  • 37” back to poplar, but 1-3/4” tall instead of 1-1/2”

Fixed Shelf

Is that still not a wide enough span? If we’re talking about furniture, countertops, or similar, a steel structural element may be the way to go. But if that’s not an option due to cosmetic or other reasons, really the only option left is to make those shelves fixed instead of adjustable. A shelf that is fixed - whether by glue, screws, a dado cut, or a combination of these methods - is held at a right angle to the upright, whereas a shelf that is resting on pins or brackets can flex much more easily.

Sagging Shelves.jpg

Shelves that are also fixed to the back of the cabinet (style #4 in the diagram below) add additional strength to the shelf as well.

Three styles of adjustable shelves (#1 - #3), and three styles of fixed shelves (#4 - #6).

Three styles of adjustable shelves (#1 - #3), and three styles of fixed shelves (#4 - #6).

Shelves fixed only at the two ends such as for an open see-thru display cabinet, or due to limits on how the cabinet is being constructed, there are more strict limits to the width of the shelf.

Returning to the earlier example of a plywood shelf without any edging strip, that 28” span could expand to a 48” span if the two ends (but not the back) were fixed instead of adjustable - shelf style #6 in the diagram above.

Or put all these things together: shelf fixed at the two ends, made of 1” thick oak, with a 1-3/4” tall 1” wide oak edging strip. That get’s you an 84” wide shelf that would easily support 30#/foot, or 210# in all, without any visible sagging.

Embedding Steel

Finally, we get to the idea of embedding steel. This is generally not an option for built-in shelves because the steel might be unsightly in traditional wood cabinetry, and a standard 3/4” thick board does not provide enough depth for a meaningful steel element to be embedded. But for other types of furniture, this might be able to be hidden - or perhaps could even add to the aesthetic.

Steel has a whole bunch of other considerations, and these are all beyond the capabilities of the Sagulator. So read on…

Shape & Weight

Steel is available in loads of shapes…

Steel is available in loads of shapes…

There is probably a few semesters of university level mechanical engineering here, so I’ll stay away from the theory. But in short, hollow shapes like a square, round, or rectangular tube, an I-beam, or even just an “L”-shaped “angle iron”, give a lot of strength without taking as much weight as a solid shape.

And the more solidly the steel is affixed to the element it’s supporting, the more effective the combined system will be in resisting forces. I recently installed a solid maple hanging countertop to hidden / embedded steel angle iron by screwing it in every 4”. Or liquid nails or a similar adhesive can be liberally applied along the entire length.

These are all great guidelines and help provide some intuition, but we want to get to something a little more concrete.

Steel Sag Calculators

Because of the range of shapes and sizes that steel can be purchased in - and the fact that it is a more uniform material used in a greater range of critical structural designs - there are many calculators that unfortunately are not as user friendly as the wood-focused Sagulator.

This is the best calculator I’ve found so far, but it requires a few additional inputs that take some effort to find or calculate.

  • Modulus of elasticity: this is a property of the material, such as steel or copper. The default value is a good starting point; this table lists a few other metals.

  • Load on the beam: this value represents the center-loaded weight for the entire shelf; typically the shelf or beam would have a uniform weight distribution. A center load puts more stress on an element than a distributed load so designing for this would be very conservative. And the value expected here is the load over the entire shelf, not the load per unit length.

  • Moment of inertia: this is a property of the cross-section of the steel, such as a hollow tube or angle iron; this site allows you to select the shape, and then enter the key dimensions of the shape; be sure to use inches, to match the only units supported by the “Easy Calculation” tool. The moment of inertia resisting sag is the value in the “Moment of Inertia Ixx (unit^4)” field.

The CivilEngineer website has plenty of moment of inertia calculators for most common shapes

The CivilEngineer website has plenty of moment of inertia calculators for most common shapes

Supporting the Shelf on Three Sides

What if the shelf is supported on three sides, rather than two? In my projects, this has come up as potential elements to calculate in a few designs. Two recent examples:

  • How much might a “floating” bathroom countertop sag (secured at the back and two ends), given it has a very heavy concrete sink?

  • Can we get a very wide adjustable shelf, that would sag too much if only supported on the two ends, but perhaps could become possible if we put some adjustable pins in the back of the cabinet as well?

And the first of these questions ended up being irrelevant: even with a ultra-conservative 300# load, the 2-1/4” thick maple countertop would sag less than 0.01” per foot, according to the Sagulator. In fact, we could almost double the length before sag becomes an issue. Add to that the fact that it would be fixed to the back as well as the two ends, and this one will definitely not sag.

eFunda Calculator Fail

The eFunda (Engineering FUNDAmentals) three sided supported plate steel sag calculator

The eFunda (Engineering FUNDAmentals) three sided supported plate steel sag calculator

However, if we needed to calculate this sag for a countertop (i.e.: shelf) fixed on three sides, this calculator comes close to helping.

The main difference in the second question is that the sides are adjustable or “simply supported” in engineering speak, rather than fixed. This calculator comes close to answering the question where the sides are not fixed.

For both, the required inputs include the modulus of elasticity, touched on earlier, as well as the poisson ratio for the material. For woods, the modulus of elasticity for many species can be found in The Wood Database, an excellent website (and print book). The poisson ratio is a bit harder to come by, though chapter four (Mechanical Properties of Wood) of the Wood Handbook, a USDA publication available for free as well as in print, lists the values for some species. It turns out the results aren’t very sensitive to the poisson ratio (so long as the value is around 0.3).

Both these “three side” calculators have three major issues, however, that limit their applicability:

  • if the length of the shelf is more than 4x the width, the results come with a warning that the approximations used may not work for this problem; indeed, I got some non-intuitive results with a shelf length 6x the width.

This doesn’t instill confidence in the results.

This doesn’t instill confidence in the results.

  • some species poisson ratios are far outside the 0.3 around which the calculator is fine-tuned

  • want to use it for more than three or four calculations? you better sign up for an account!

Fusion360 Fail

But wait! Fusion360, in which I do all of my photorealistic rendering, and much of my CNC designing (see this blog entry), does robust engineering analyses. Granted, it isn’t as straightforward as a calculator, but for those larger projects with structural uncertainty, it is probably worthwhile to model and verify, rather than to find out too late the design will fail.

In writing this blog, I got so excited by this solution that had been lurking on my laptop all along, so I designed a simple but super wide adjustable shelf to test it out, putting in a few different options for how many pins to provide for back support over the 5’ span.

Sag analysis problem.png

This screenshot of the results shows what would happen if the shelf were made of ABS Plastic. Or I could choose any of a variety of other plastics, copper, one of dozens of steel grades, or other metals and engineered / refined products.

A shelf made of polystyrene just won’t cut it!

A shelf made of polystyrene just won’t cut it!

But no wood species can be modeled - the material properties aren’t defined in Fusion360. Or more specifically, at present, only isotropic materials can be modeled. That’s a fancy way for saying that wood strength depends on the direction of the grain, which is far more difficult to model than uniform materials like plastics and metals.

Opportunity for Future Online Tool

So it seems this is an area where - at least at present - detailed analysis will depend either on a (typically in the low thousands of dollars or more) professional structural engineering evaluation, or more likely given that high cost, intuition and overdesign to avoid potential problems.

Do you have a structural engineering background? Want to conquer this area for all posterity to benefit? I’d love to partner with someone to make a new calculator available to the woodworking community!

Is Using Wood Bad for the Environment?

David Wertheimer3 Comments

This post is motivated by a number of conversations that have made me think about the potential contradiction in my environmentalist tendencies and my using wood as my primary medium. Paraphrased for brevity:

  • Friend#1: "You put up solar panels, yet you cut down trees..."

  • Friend#2: "Most people don't know where the 'material' of trees comes from..."

So, here’s my attempt to square this circle.

How much wood is harvested annually?

It's tough to come by well-vetted (and current) stats, but here's a few from Wikipedia:

  • The worldwide growing "stock" of forests is about 434 billion cubic meters (2005).

  • The annual wood harvested for all purposes is about 3.5 billion cubic meters (1991), though estimates of wood used for burning have wide ranges. This represents about 0.8% of the growing stock.

  • The annual "roundwood" (officially counted wood not used as firewood) harvested is 1.5 billion cubic meters (1998).

How much is a cubic meter? If you're familiar with your typical eight foot 2x4, there's about 100 of them in a cubic meter. An average 2000 square foot house uses the equivalent of roughly 1875 2x4s for framing, so that means that was enough wood harvested in 1998 to frame 80 million comfortable homes.


Translating that to my business - I purchase wood by the "board foot", which is one square foot of lumber 1" thick, or one twelfth of a cubic foot. Big projects - such as the 24 oval mirrors for the Southern California carousel rebuild - use a few hundred board feet (about 1 cubic meter).

However, most of my small products, such as this popular lamp, use between a quarter and a half of a board foot. So you could make 150 of them from a cubic meter of wood - or in 1998, if I had cornered the wood market, I could have made 225 billion of these lamps, enough for every person on the planet to have about 30!

But just saying I don't use much ain't much of a defense. So, is using wood good?

What's the alternative to wood?

If you want a lamp, or some coasters, or a shelf, you could purchase something made of plastic, or glass, or any of a hundred other materials. And many of these materials don't involve cutting down a tree. But, many of these materials are far worse for the environment overall taking into consideration all of the “embodied energy” and “embodied carbon” that goes into creating an object.

Said another way, though it’s always better to consume less, if you are going to consume, do it with goods that take less energy to create, and leave less of a carbon footprint on the planet.

Illustrative breakdown of the stages of a product or material life that should be considered when understanding the carbon footprint.

Illustrative breakdown of the stages of a product or material life that should be considered when understanding the carbon footprint.

That's one reason why I'm happy to say that my workshop (and my vehicle) is powered by solar energy; while that's just a small piece of the overall ecosystem, that also reduces the environmental footprint of what I sell.

For a much more scientific and detailed analysis of hundreds of materials commonly used in construction and elsewhere, check out this paper. For example, the average sawn hardwood has about 7-10% the energy per kilo that the typical plastic contains, and about a quarter of the embedded carbon.

In fact, wood has a far lower embodied energy and carbon content than almost every other material that might be commonly used for home decor. So while it’d be better to not purchase anything at all, if you do, use wood!

Is burning wood "bad"?

I periodically host a bonfire to get rid of scraps I accumulate - primarily construction-grade framing wood, but also occasionally scrap hardwood that I just can't find a home for in either my own projects or via with my fellow artists.

This produces soot & ash which isn’t great for the local air quality but - on a small scale from limited camp fires and bonfires - has fairly modest impact. In larger scales, however, there are clearly bad effects: Northern California briefly took the crown of having the world’s worst air quality in mid-November due to the tragic Camp Fire; breathing the unfiltered San Francisco air for a day then was equivalent to smoking a half pack of cigarettes.

Battling the Camp Fire, Nov 2018

Battling the Camp Fire, Nov 2018

Or - not quite as tragic but just as bad for our health - lower-income regions that rely on wood for cooking and heat have very bad air quality, as I personally witnessed in parts of the Himalayas in mid-October. For this reason, it seems parts of China - including Tibet - have outlawed wood stoves, and the U.S. EPA has similarly banned inefficient wood burning stoves a few years back.

But beyond that, does this contribute to global warming, or other types of air pollution?

Goodbye, failed early attempt at a round coffee table, c. Nov 2017.

Goodbye, failed early attempt at a round coffee table, c. Nov 2017.

Wood treated with anything (paint, insect protection, stains), or composite wood products (plywood, particle board, etc.) is a definite no-no, for the very bad toxins that this releases into the air.

But how about "raw" untreated wood? Logs you've cut down from your property, that old pallet sitting in your backyard, or some wood scraps? You may have heard wood referred to as a "renewable" or "carbon neutral" resource - how is this so, if burning it releases CO2 into the air?

That's because that carbon in the tree came from the atmosphere in the first place, as the tree grew from a seed. Trees breathe in CO2, and breathe out O2, in the process called photosynthesis - those “C” carbon atoms, over time, become the "wood" that is the tree. So while the bonfire alone isn't carbon neutral, in the relatively short lifespan of the tree, the growth-to-bonfire process is carbon neutral. And if you didn't burn it, as the tree decomposed over time in your backyard or in a landfill or as mulch, it would release the same CO2 back into the atmosphere.

Compare that to burning fossil fuels, which prior to combustion were sequestered deep underground, and would have stayed there if not for their extraction. One could say that over the time horizon of millions of years it took the oil to form to when it was ultimately burned, that too is carbon neutral! But over the few hundred years that we have existed as an industrial society, however, this is not carbon neutral. That additional carbon sits contributes to global warming (or gets absorbed by the ocean, acidifying the water, or having other deleterious effects on our global environment).

Is this the Final Word?

Wood is better than many alternative materials. And at least from a carbon neutrality perspective - though not from a localized air pollution or a deforestation perspective in certain regions - wood is an acceptable fuel. But that’s not to say we can cut down all the trees: cutting down one tree from a forest is different from harvesting the entire forest!

Indeed, there’s a lot more to responsible harvesting for forest management. Entire organizations exist to help manage, educate, police, and certify producers. And - spoiler alert! - it has nothing to do with “raking the forests” of leaves, as Trump ignorantly claimed in a recent conversation. Trees - like animals, and ecosystems in general - can also become endangered or at risk. All of these will be topics I cover in future posts.

Is there a particular environmental concern you have with forestry management, or consuming wood products? Email me or leave a comment - I’d love to hear your thoughts.

Woodcarving with a Nepalese Master

David Wertheimer2 Comments

I was in Nepal in most of October, hiking through the Himalayas, munching on momos, and enjoying the local culture. One thing that is quite visible as I wandered around the Kathmandu valley was that there’s a long tradition of amazing wood carving in the architecture.

Each window and door jamb and lintel has amazingly detailed Newari carving.

Each window and door jamb and lintel has amazingly detailed Newari carving.

A typical Newari window; photo credit to Osman Khawaja

A typical Newari window; photo credit to Osman Khawaja

First, a brief ethnic background. Nepal is a country of many ethnic groups - the two biggest groups compose less than 30% of the population and there are 18 groups that comprise more than 1% of the population each! The Newari are one such group, just under 5% of the population as of 2011.

The Newari are the historical inhabitants of the Kathmandu Valley and its surrounding areas in Nepal, and are major contributors to the artistic and cultural community in the densely populated Kathmandu Valley. Among their many artistic contributions are the elaborately carved wooden windows, a distinguishing feature of traditional Nepalese architecture. The artistry reached its peak in the mid-18th century, visible on palaces, private residences, and sacred houses.

Though many historical sites - and the Kathmandu Valley region in general - suffered immensely in the 2015 earthquake as the traditional local architecture is primarily made of brick, many of the homes and buildings with these amazing carvings are still standing today. A few very talented master carvers are helping to recreate those pieces, restoring those devastated older homes, as the stretched-thin budget of Nepal allows.

This ain’t “redtagged” - its still used as a home

This ain’t “redtagged” - its still used as a home

A much more obvious collapse, waiting for reconstruction

A much more obvious collapse, waiting for reconstruction

The leaning walls of many homes - and quite a few temples - are temporarily (since 2015!) reinforced

The leaning walls of many homes - and quite a few temples - are temporarily (since 2015!) reinforced

Via Backstreet Academy - a website that connects travelers directly with artisians and local tour guides working for themselves in Nepal, Cambodia, Laos, and elsewhere in Southeast & South Asia - I connected with one of those skilled craftsmen, Heera Ratna Bramhacharya, for a four-hour one-on-one class in his home & workshop.

Practicing carving straight lines, more difficult than I expected to keep it at the same depth!

Practicing carving straight lines, more difficult than I expected to keep it at the same depth!

Heera is an amazingly patient instructor - after taking me through a few basics and an introduction to the handtools, I practiced on one side of a small plaque before doing the “final” carving of a Nepal “sign” on the other. In addition to selling pieces in his small shop - about half to tourists and half to locals - he supplements his income with these small and one-on-one classes, as well as aiding in some of the rebuilding efforts.

My finished piece. Though I’m happy how it turned out… I think I’ll stick to my current area of expertise!

My finished piece. Though I’m happy how it turned out… I think I’ll stick to my current area of expertise!

Originally from Bungamati - a village about 7 miles from the center of Kathmandu - Heera learned woodcarving from both his grandfather and father. And in addition to teaching tourists like myself for interest, he also teaches local women who supplement their family income by carving small ornamental strips for him that he then incorporates into his larger pieces.

Small Embedded Window.jpg

What took me four hours to carve, he probably would have whipped out in 15 minutes - he mentioned he could carve the majority of (the central portion of) one of these smaller windows in a day, and he typically does a 10 hour day carving, sitting cross-legged on the floor. (After 30 minutes, both my legs had fallen asleep and I couldn’t stand anymore!)

While smaller pieces were fairly inexpensive, don’t get planning too much ahead: for those looking to incorporate one of these amazing windows into a coming remodel, something like this might cost about USD$20,000!

This bay window set on the upper floor might cost $20,000! Extra for the “peaceful” dog.

This bay window set on the upper floor might cost $20,000! Extra for the “peaceful” dog.

"Do you miss the office job?"

David WertheimerComment

In sharing my story with both fellow artists and customers at the weekend art shows, I am often asked if I miss my former “day job” at Google - while my story isn’t unique, it definitely isn’t commonplace either. And never is this more top of mind than when I’m in Mountain View, as I was earlier this month for their fall Art & Wine Festival, as I run into many former colleagues and current “Googlers”.

Given that it’s now been a full two years since I regularly went into the office, this is as good a time as any to share some reflections on whether the fears I had at the time I made the leap became real, what I miss (and what I don’t), and other musings for those considering pursuing a similar leap.

But in a word: NO! I definitely do not miss the office job - hopefully all the posts of the past two years have made clear how much I’m enjoying my new gig, though it does have its challenges. Nonetheless, there are certainly some elements of the tech world that I do miss.

My (Unfounded) Fear When I Left: Laziness

I was worried that, with my newfound freedom, I might sit on my ass and watch TV all day, pursue a few interests for a few weeks or two months, read a few books, and then have nothing to do, nothing that fulfills me or makes me happy.


Those who know me well will probably tell me this was never a real risk, but taking such a major leap - when Branching Out Wood wasn’t yet set up - was a little scary.

Turns out that, even without a 9-5 (or more realistically, 7:30-6:30p) day job, there still ain’t enough time in the day to do everything I want to, between this business and attempting (and failing) to get another business off the ground, volunteering, and yes, of course, reading a bit more. And indeed, travel has become more easy: I have taken a few family and personal trips I probably wouldn’t have done before, and am about to embark on a trek through the Himalayas.

So, nope, laziness was not a problem - I still don’t “relax” or “lounge” very well!

An Unexpected Challenge: Social Interaction

However, there is one challenge I did not anticipate: lack of social interaction. Sure, I probably have roughly the same social life in the evening and weekends now that I did when I had the day job.

But the day job was also very social. There are continuous water cooler interactions and lunchtime conversations that one friend described it as a “slow running soap opera”, where you feel connected to a wide network of colleagues’ kids and family drama, pets and remodels, commute woes and exciting travels well beyond your core group of close officemates.

Contrast that with my day job now: most days I’m working in my workshop, a solitary affair. Weekend festivals and social interaction during commissions make up for that a bit - a special thanks to everyone who has stopped to have a friendly conversation at a show, or engaged online or with a project. And the artists I’ve met both at shows and online have been without fail incredibly warm and friendly. But that’s a bit different than the daily din and repeated interactions that comes from an office job. Or at least I need to learn to be more proactive in building that into more of a personal community.

To fill the gap, I’ve cultivated (and, yes, had the time to cultivate) a few friendships with some fellow entrepreneurs, as well as built a few relationships with folks that I’ve done volunteer work alongside of or with - thank you to George, Tina, Dawn, … and many more.

This is something I’m still working on, and something that I miss more than I expected, or even considered.

Important disclaimer: do not refer to this drawing for proper or safe table saw technique. And you see why I do woodworking and not, say, painting!

Important disclaimer: do not refer to this drawing for proper or safe table saw technique. And you see why I do woodworking and not, say, painting!

Necessary Lip Service: Food & Healthcare

Yes, of course, I miss the free food from Google. But I’ve lost five pounds, and am cooking a bit more.

I miss the gold-standard healthcare, though I’m now a proud card-carrying Affordable Care Act member. However, the “bronze” level just doesn’t hold a candle to Google’s plan - even the “gold” doesn’t compare. Fortunately, I’m in good health and this isn’t a major pain point. It has, however, changed my behavior a little: I’m perhaps not as willing to go skydiving now, whereas I went three times in the last five while covered by my employer health insurance.

Being a Part of Something Bigger

On less-materialistic considerations, I do miss both the deep insight to technology trends and the connection to much larger scale projects than anything I am undertaking now. My role at Google gave me previews of specific technology and trends one to two years before they were announced by us or partners with any detail, and my team had influence over multi-billion dollar investments; I heard of the responses to major security threats and attacks that, on the outside, get a paragraph of vague description in an industry rag - or perhaps no mention at all.

I’ll confess I have no particular passion for, say, hard drive caching technologies. But I was fascinated by how evolving mass storage technologies can affect, say, how racks of servers, and thus cooling infrastructure, needs to be laid out. Or more generally, how one small piece of a physical system interacts with a much larger system in non-obvious ways.

Being a part - even if just a small part - of building and running a much larger (cutting edge) system was rewarding in a way different from the satisfaction I feel in building and delivering a beautiful product.

This, like the social interaction piece, I’ve attempted to replace: by volunteering with Habitat for Humanity on an ongoing basis for some of their larger projects; by trying to fill a niche in the solar industry space to grow clean energy adoption; by getting involved, albeit briefly, in some local political issues.

But I feel that, unlike everything else I’ve spoken about so far, this point was uniquely met by the group in Google that I was a part of - this is an aspect that may not be easily replicated in any job.

So Why Not Go Back?

That’s a lot of things to miss, some of which can’t be replicated at a sole proprietorship. So why not go back, to Google, or to another company with similar large scope and complexity (i.e.: a solar company)? I won’t say never, but … I don’t miss the horrible commute; the freedom to deeply explore my creativity and create beautiful things; the time to read a good book or book a trip whenever. And I definitely don’t miss the politics and challenging personalities inherent in any job.

Though it’s still work, now, each day I get to set my own goals and explore my own projects. And I’m able to enjoy beginning each day - and perhaps this also helps with the creativity? though probably not with the table saw! - in a relaxing way with my very own home-made Irish coffee.

Keep It Simple Stupid!

David WertheimerComment

Most of us have heard that saying at some point in our lives: Keep It Simple Stupid (KISS). First coined by the US Navy as a design principle in the 1960s, it's something that I need to periodically remind myself.

Sometimes, however, the engineer gets the better of me. You can see that in the incredibly elaborate mechanical and electrical system I built for my version of the sand plotter in comparison to the simple mechanism designed by Bruce Shapiro for his Sisyphus. Though I got some great learnings from attempting to tackle that project, my version has ended up in the scrap heap.

Well, a more recent project has reminded me of this principle yet again, at the cost of a $400 burned-out circuit board, not to mention the development of the over-engineered solution, costing much more in coin and sweat over the weeks I attempted to get it working.

The Problem: Balancing the Garage Lift

I set up my CNC late last year in my workshop; to move it out of the way when not in use, I put it on the Garage Gator lift, which was the only affordable motorized lift I could find. It comes with a 4' x 6' platform, more than enough for my 1000mm X Carve, but unfortunately, it has one major limitation: the platform has only two cable attachment points to the lift mechanism. That means that if the platform isn't perfectly weight balanced from front to back, it will tilt and dump everything on the floor! (AuxxLift and PowerMax have four cable systems, but at the time, I wasn't ready to drop $1000+ on a lift, several times the cost of the GarageGator. In retrospect, that would've been a much better solution!)

I didn't want the CNC platform to list like this as I raised it into the ceiling...

I didn't want the CNC platform to list like this as I raised it into the ceiling...

... given the single point suspension of the lift at the ceiling!

... given the single point suspension of the lift at the ceiling!

So as I lift the CNC into the ceiling, I have to be very careful to make sure the platform is balanced front to back. Sure, I could do this manually... but this could get super tedious if I'm using it every day, so this led me down a tortuous path to automate the process.

Solution # I: Sliding Counterweight

Fortunately, the platform had extra space to the side of the X Carve, so I decided on a simple solution using a heavy counterweight that would be shifted back and forth based on the tilt detected by a pair of mercury switches. This was simple only in idea:

  • Finding the counterweight. Steel or brass would be ideal, but an 6" metal cube, weighing in at about 60 pounds, was surprisingly expensive. So I decided to pour a concrete cube. At about 30% of the density of steel, I poured a 9" cube to get the same weight. But a cube of concrete isn't as smooth as metal, even with the wood form kept on and a plastic slider underneath, so you run into problems...
  • Moving the counterweight. The mechanics were simple: I used a threaded rod that ran through the concrete block, attached to a geared down low speed low voltage motor. But the first motor wasn't nearly strong enough. The second motor, a "Maker Motor", had just enough torque, but drew between three and five amps, which means I had to be careful in ...
  • Powering the movement. 3A at 12V is fairly modest in power supplies, but no mercury switch I could find could handle that, so I had to add a pair of relays. Actually, I would have needed at least one relay anyways to make sure that a delayed opening of a mercury switch (or bad positioning of them) wouldn't lead to a short circuit in reversing the motor direction and current.

Wow that simple idea took a lot of parts and time. But it largely worked... with one major (and critical) flaw that I hadn't considered prior to putting all the pieces together: weight. The Garage Gator has a 200 pound capacity. The X Carve I have is about 110 pounds. The torsion box adds another 40 pounds. With the 60 pound counterweight, another 30 pounds of other stuff attached to the platform, and random projects left on, I'm well over the weight limit. Though I have safety chains to hold the platform in place should a Garage Gator gear fail while the platform is in the air, I don't want to run any risk of the lift dropping everything on the floor as it attempts to pull the platform to the ceiling, or of getting pancaked underneath the platform! Better safe than sorry here...

So, back to the drawing board.

Solution #2: Double-Duty Gantry

Wait! I don't need a separate 60 pound counterweight - the gantry on the X Carve itself can slide back and forth, and since it carries the hefty router as well, this would serve as a perfect counterweight without adding more pounds!

The gantry is that bar outlined in white, that slides back and forth with the router (the yellow thing - it does the actual carving) attached. Circled in red is one motor that moves the gantry; there's an identical one on the opposite end. The "X Controller" is outlined in turquoise - not much of a picture - but we'll return to the electrical insides of this later.

The gantry is that bar outlined in white, that slides back and forth with the router (the yellow thing - it does the actual carving) attached. Circled in red is one motor that moves the gantry; there's an identical one on the opposite end. The "X Controller" is outlined in turquoise - not much of a picture - but we'll return to the electrical insides of this later.

But it does add a lot of electrical complexity (which is why I did not pursue this idea first). That is, the gantry is moved by a pair of stepper motors, which are ordinarily controlled by the circuitry that comes with the X Carve (called the "X Controller"). And I definitely want to make sure I don't damage that circuitry by, perhaps, sending current back into the device when its not expecting it.

So that means there's two problems I have to tackle: first, making sure my counterbalancing system only turns on when the X Controller is off, and second, having those mercury switches activate stepper motors rather than a simple DC motor.

For the first part, I found this nifty little device and routed the X Controller power through it. When attached to a relay, that ensures that the counterbalancing controls are only powered up when the X Controller is turned off.

The second part allowed me to reuse some of the learnings (and parts) I had gained earlier with my abandoned sand plotter project, using an Arduino microcontroller and a pair of stepper motor shields, I could control the two motors.

It worked with a basic test! Or so I thought... but I'll come back to that.

Since I had a fairly large project box (and a multi-voltage power supply), I took advantage of the extra space for some other electrical enhancements I made: extra LED lighting; the power for the laser module; the foundation for a future closed loop speed controller for the router via the Super PID. So that spacious box became quite crowded afterall.

Can you figure out what's going on in here? Yeah. Neither can I. But I'll try to explain...

Can you figure out what's going on in here? Yeah. Neither can I. But I'll try to explain...

Red: two power supplies, one for the 24v of the laser, and one for the 5v & 12v of the steppers, LEDs, and digital circuitry. Blue: the Arduino and stepper motor controller. Green: mercury tilt switches. Yellow: three relays, two to separate the two stepper motors from the X Controller, and one for the laser module. Orange: Dwyer current switch to detect when the X Controller is on. Turquoise: the power input / output, for two independent circuits so that the high power router of the CNC can be separated from the more delicate circuitry, and allowing for future router speed control. Purple: Wow there's a lot going on in here, we should probably have some fans to keep it all cool!

Red: two power supplies, one for the 24v of the laser, and one for the 5v & 12v of the steppers, LEDs, and digital circuitry. Blue: the Arduino and stepper motor controller. Green: mercury tilt switches. Yellow: three relays, two to separate the two stepper motors from the X Controller, and one for the laser module. Orange: Dwyer current switch to detect when the X Controller is on. Turquoise: the power input / output, for two independent circuits so that the high power router of the CNC can be separated from the more delicate circuitry, and allowing for future router speed control. Purple: Wow there's a lot going on in here, we should probably have some fans to keep it all cool!

Looks so much cleaner and actually organized from the outside!

Looks so much cleaner and actually organized from the outside!

The inputs & outputs for the steppers, the main power, and various low voltage supplies.

The inputs & outputs for the steppers, the main power, and various low voltage supplies.

But everything "unit tests", or works when individually tested, so I plug it all in and start using it. And there's two problems.

Those four big chips at the back are the stepper motor drivers for the X Controller, much heftier than those used with my Arduino.

Those four big chips at the back are the stepper motor drivers for the X Controller, much heftier than those used with my Arduino.

First, it actually doesn't work. The stepper motors require a lot of power, especially given the weight of the gantry and the router. The X Controller has a very powerful chip, the Toshiba TB6600, to drive those motors.  You can see the four big vertical chips at the back of this board.

The driver I'm using attached to the Arduino is puny in comparison. So while it does attempt to move the gantry in the correct direction, because that movement is against gravity - that is, if the platform is tilted forward, the circuitry will attempt to move the gantry uphill in the opposite direction until the platform starts leveling out - there just ain't enough power. I try increasing the motor voltage from 12V up to the driver limit of about 15V, but still no go. In fact, the driver starts shutting down due to overheating. Drats.

But it doesn't cause any problems, so I just leave it in place. And a few months go by, until I finally get to a project where I start using the 24V laser engraver that is also powered by wiring in the same project box. I don my goggles, get the fire extinguisher handy, turn on the laser, and start smelling something smoking. Not the smoking of a laser that is burning through the wood - I smell that too - but the smoking of burning electronics.

Still, as I'm unsure, I turn everything off, and then repeat the experiment. And this time, I start seeing smoke coming from the X Controller. Double drats!

After opening up the X Controller, I can see that one of the four high power stepper motor chips has been fried! I don't try to troubleshoot my rats nest of wiring; rather I just disconnect the whole darn thing, and cry. Or more specifically, I reach out to Inventables, the manufacturer of the X Carve, and I explain the fried chip.

Check out the vertical black chip, second from right. See that brownish-black stain on it? That's a burn mark, presumably somehow caused by my separate controller sending power back to this board at the wrong time. Exactly what was the root cause, I never figured out. But I did figure out that this board is now fried.

Check out the vertical black chip, second from right. See that brownish-black stain on it? That's a burn mark, presumably somehow caused by my separate controller sending power back to this board at the wrong time. Exactly what was the root cause, I never figured out. But I did figure out that this board is now fried.

Kudos to them, amazing customer service, they ship out a new circuit board with priority shipping. So a few days later, I'm back up and running, but with a much reduced and simplified wiring setup: an independent regulated power supply for the laser, and nothing else.

But I still have the problem of balancing the gantry...

Solution #3: Biomechanical Feedback System (KISS)

Finally, I've found a solution that works: turn the power to the CNC off. Then manually move - with my hand! - the gantry to the position where the platform is balanced. Voila! It works!

Final solution : If the table tips forward, push the gantry to the back (in the direction of the red arrow). If the table tips backward, push the gantry to the front (in the direction of the blue arrow).

Final solution: If the table tips forward, push the gantry to the back (in the direction of the red arrow). If the table tips backward, push the gantry to the front (in the direction of the blue arrow).

Granted, when I started trying to solve this problem, I thought I'd be raising and lowering the CNC daily, perhaps several times a day, whereas after a few months of use I find I lower the CNC for a project - which may last one day or three weeks - and then only when done with that project, raise it back up. So rather than balancing the platform 300-600 times a year, it'll probably be 20-30.

If I could start over, though, I'd get that more expensive garage lift... or maybe its just time for a larger workshop!

Furniture Rendering Software

David WertheimerComment

I've used a few software modeling and design packages over the years to help with architectural drawing and furniture design, starting first with Claris CAD on a much-earlier Mac in the mid 90s in high school!

Though I considered myself an expert on that, having taken a few semester-long classes on it, and continuing to use it for personal projects in the years just after college, a few computer upgrades, and operating system changes, combined with a multi-year hiatus from woodworking (and the related drawing), meant that I had to start over whenever I needed to draw since then.

I've never spent enough time with any other packages in the intervening years to consider myself even just "proficient", dabbling in AutoCAD, LibreCAD, QCAD, and SketchUp when a need to produce something more precise or complex arose. But when I added the CNC machine to my shop - see more about that here - I knew I needed to learn something that could send commands to that tool.

The XCarve CNC comes with a free subscription to the web software Easel for exactly that purpose, but while Easel is incredibly easy to learn, it's also incredibly limited in it's capabilities. After reading a lot of reviews - and focusing on three key criteria of free, Mac-compatible, and XCarve compatible - I came across Autodesk's Fusion360 software.

I'm still no expert in this software. Indeed, its so powerful it seems like folks might spend years working with it, and still only know one small area in depth. But it's become my go-to tool now not only to drive the CNC, but for rendering commissions.

This isn't a tutorial - I'm far from knowledgeable enough to even consider that, and there seem to be hundreds of great sources for that already. But rather, this is just an opportunity for me to share a few of the different renderings I've done for clients.

Entryway Shelf & Mirror

Though the design wasn't complex enough to require a rendering, as the client considered different woods for the surface, this really helped them finalize the walnut and maple combination.

For far more details on this piece, check out this post.

Oval Mirrors

A commercial client refurbishing a carousel in Irvine needed 24 oval mirror frames, each of which was comprised of 4 pieces end-joined with tenons. While this may have traditionally be cut with a template, I found it much easier to do with the CNC. So here, the drawings were only necessary as a way to control the CNC.

Sun Catcher

Sun Catcher.png

An in-progress addition to my catalog, a pair of these wooden pieces will sandwich nine stained glass tiles. This also gave me opportunity to learn and take advantage of constraint-based modeling, wherein instead of defining a model by the length of each line, the model is defined by relationships between the lines such as "perpendicular" or "equally spaced", so if I want to change the size of one side, or the size of the glass inserts, rather than redrawing the entire piece, I can just update one number and see the entire model update.

Nixie Clock

The body of the long-in-progress Nixie clock I just recently completed was first attempted via manual milling with my drill press; this was the initial impetus for the CNC. This used the CNC in th places: milling out the wooden block; drilling out the control panel; and then engraving the logo and the control panel labels.

Cable Box

A request came in for a decorative box to hide a cable box and media devices and cables, with a built-in shelf and ventilation holes that I designed to double as handles. This was never built.

Cable Box.png

Boathouse Shelf

This oddly-shaped shelf is for a kitchen counter of a boathouse in Emeryville; the rendering helped her understand the final product. I also took advantage of the capability to produce projected dimensioned drawings very quickly from a model; as I updated the model, the projected drawing also automatically updated, making it much easier for me to build the final product.

Screen Shot 2018-04-09 at 5.33.53 PM (2).png

Entryway Tray

The original request to feature a purpleheart stripe led to the rendering at left, which helped refine the design to what I ultimately created at right.

Kitchen Bench & Built-in Storage

This client had a firm idea of what they wanted for the kitchen, but was a bit more nebulous on the wall of bookshelves & desk for the study. Regardless, as both pieces were fairly substantial, a detailed line drawing, and a rendering in white paint helped advance the conversation.

Fusion360 Plug

OK so I'm obviously quite new to the modeling (as opposed to drawing) world: wow, it automatically produces projection drawings for you? This was probably news fifteen years ago! And I'm just barely scratching the surface of the software's capabilities - for instance, I could do a structural analysis of anything I model as well!

Not bad for free, eh? So long as you have under $100k in revenue - or use this for academic purposes - it's free. So check it out, or share your thoughts on what software you know and love!

And... if anyone has software to open those 1990s-era Claris CAD drawings I did way back when, let me know! I'd love to see what crazy (or probably quite mundane) designs I was coming up with back in my teens.

2018 Show Schedule

David WertheimerComment

2017 was a year of learning what shows might work, and which ones I needn't repeat. So I'm super excited for my 2018 show schedule, with the new ones in bold:

  • May 5 & 6: Mountain View a la Carte
  • Jul 14 & 15: Los Altos Arts & Wine Fest
  • Jul 21 & 22: Menlo Park Summerfest
  • Aug 18 & 19: Burlingame on the Avenue
  • Sept 8 & 9: Mountain View Art & Wine
  • Sept 15 & 16: Mill Valley
  • Sep 22 & 23: Oakland-Montclair Village
  • Oct 6 & 7: San Carlos Art & Wine Fest

Dropped from this year are Lafayette, Novato, and Alameda. Also, I'll probably end up at at least one of the monthly Treasure Island, Oakland Jack of All Trades, or Oakland Museum of California events, though none are yet booked.

Come visit!

CNC & Torsion Boxes

David WertheimerComment

I've really enjoyed working with my CNC so far, though I'll confess, I've been doing mostly prototyping - and one giant commission of twenty four oval mirror frames - with no finished products in my catalog yet to show off. But a lot of the time I've been spending with the CNC has been setting it up just right.

As mentioned in an earlier post, many of the next posts will be about the nuances of getting this thing set up, and with the first in the series, I'll talk about "torsion boxes". A torsion box is just a fancy word for a common construction technique where two thin layers of material are applied to either side of a lightweight core.

Flat, Light, & Strong


The most common example that we interact with every day is a "hollow core" door, that is, probably the type of door inside your house. They're super flat, fairly light, and yet very strong. If you were to peel back the thin wooden skin on one side of that door, you'd see a grid of material perpendicular to that skin made of something light and cheap- thin wood, or perhaps even cardboard, depending on the door quality. But they're also used in ships, furniture, some bridges, and many other places as well.

A few months ago, I bid on a kitchen cabinet project that included some 2" thick 15" deep shelves edge mounted on the wall. A 2" thick shelf, if made of solid wood of any variety, would be really heavy and expensive. For instance, a walnut shelf that large would be 0.7 pounds per inch of length, or 25 pounds for a 3 foot section. Mounting three of these on the wall with hidden hardware would be challenging to say the least. Solid wood also expands and contracts with moisture and temperature, making it more challenging to use for large solid wood furniture - see this blog for some more details about that. However, if made with 1/4" veneered MDF (medium density fiberboard) - a very smooth engineered product used as the core within a lot of furniture - the weight would be cut by more than half, to about 12 pounds for that same shelf.

Gaining Extra Height

Now let's return to the world of the X-Carve CNC. I added some extension brackets that allow me to work with much thicker blocks of wood with the machine, up to about 4.5" thick. But the X-Carve z-axis only goes up & down about 3", so that means that for the more common thinner stuff that I'll be cutting and carving, such as a cribbage board or a customized cutting board, the cutting head wouldn't be able to reach the material.

You can see one of the silver brackets giving my machine an extra 2" of height in the lower left

You can see one of the silver brackets giving my machine an extra 2" of height in the lower left

Here's where the torsion box comes in. By adding another 2" layer to the bottom - kind of like a high chair for my CNC - that negates the effect of those brackets, so that I can work with standard-height materials again. But it's critical that the surface be perfectly flat, so that it doesn't introduce any errors into the CNC.

Bonus: Vacuum Clamps

Instant 60 pounds of clamping force

Instant 60 pounds of clamping force

One other great bonus of this setup is that I can now easily use my vacuum clamps. The vacuum pump I purchased is great for veneering, but with a vacuum, you can also easily clamp flat items - like that cribbage board, cutting board, or a sign - if the underlying surface is also flat.

In fact, every square foot of clamping surface exposed to these vacuum clamps produces about 1300 pounds of clamping pressure. The vacuum clamps aren't a square foot - they're closer to 2.5" x 2.5", which produces only about 60 pounds of clamping force, but that's still huge - especially given that they do not mar the surface of what you're clamping, provide complete access to the top of the item, and are nearly instant to insert and remove, with the aid of a foot pedal.

The X-Carve "waste board" - the gridded board you see in some of the pictures - is perfectly flat. But it also has about one hundred holes drilled into it, so that you can use screw clamps. You can see those in that picture above as the green and blue plastic inserts sticking out of the board. They're very useful in their own right, but they limit the use of the vacuum clamps since, unless they are very carefully placed, the vacuum just goes right out the other side of the board, through those holes.

Wrapping It Up

So there ya have it - now you know what a torsion box is, and you could even make your own door if you so desired! But if you'd rather have me make the doors - or anything else for your home or business - look me up! I'd be delighted to explore your project with you.

How to Build a Cabinet in Ten Easy Steps

David Wertheimer1 Comment

I’ve been fortunate to get a number of commissions, both large and small, in the past few months, which has kept me from making a more recent post up, but it has also given me a bit more to write about.

Today, I’ll drill into one of those commissions in detail, share the construction considerations, and show some of the steps along the way.

Interested in discussing a piece? Send me an email or give me a call!

Entryway Shelf & Mirror

The request from the client was for hanging entryway shelf for their recently completed remodel, to fit between the angled walls. After a little more discussion about what woods might look nice together and complement their decor, they decided on walnut and birdseye maple, and for a wall-mounted mirror frame above.

The client provided a template for the top and the desired width. We had to go the template route - rather than me personally taking detailed measurements - as the piece would be installed in a condominium in Florida. After going through a few more detailed questions about design - top surface overhang, depth, etc. - I was able to produce this rendering that the client signed off on.


Veneer or Solids?

There are two main construction techniques that were possible here: solid wood, or veneer. As touched on in an earlier post, though solid wood has some advantages, for something of this size - especially as it will be installed in a home in Florida - would deteriorate over time if made of solid wood with glued joints. Not to mention finding or joining together boards of that size would be either a lot of money, or time, or both. So that steered me towards a predominantly veneered MDF (medium density fiberboard, an incredibly smooth and stable engineered wood product made of wood fibers glued together under considerable heat and pressure) construction technique for the large top and bottom.

However, the front edges would not be great as veneered: as they would get a bit more abuse from bumps, I decided to use a thin strip, approximately ⅛” thick, of solid walnut as the “edge band”, and for the veneer to cover the top and bottom of that as well so that it would be indistinguishable as an edge band. Much thinner than ⅛” , and it might as well be veneer; much thicker, and you run the risk of “telegraphing”, where that edge band of solid walnut “moves” (expands and shrinks) with the changing temperature and humidity, but with the more stable veneer and MDF glued on the top and bottom, gets stretched.

I also decided to make the three vertical uprights of solid wood, for a few reasons. As they were much smaller, I had neither the challenges of cost of availability, or weather stability, of the top and bottom. And I decided to remove about half of the material on the outer edges of the two sides to make fitting to drywall that might be bowed slightly, much easier. This removal of material would pose problems for veneered MDF, such as significantly reduced strength in comparison to solid walnut, and the fact that you typically need to veneer both sides of a board to prevent stresses from the veneer from warping the board over time but yet veneering such a shaped piece would be a lot more challenging.

The drawer fronts and drawer boxes would also be of solid wood, walnut and poplar, for appearance and durability, and similarly, because as much smaller pieces, they would not have the same cost or stability problems as the top.

Drawer Boxes

Finally, the drawer boxes and slides posed a little bit of a challenge: given the shape of the drawer fronts and overall cabinet, I could do either rectangle drawer boxes with conventional drawer slides and overhanging drawer fronts that would significantly reduce the size of the drawers, or trapezoid drawer boxes that would have to use simpler undermount slides. The conventional side-mounted slides would allow for very high quality soft-close slides, and “push to open” slides, that a lot of clients like, but the client here opted for the trapezoidal larger drawer boxes with these wooden drawer slides.

So there we have the logic and thought process in the construction and material choices. Now let’s get to work!

Construction Steps

The rough step-by-step is below, with a few steps where I learned a bit more via trial and error, or to explain more nuance, covered below. But first, some pictures along the way!

  • Cut the the ⅛” walnut strips, and glue them to the long edges of an MDF panel; sand to make sure the top and bottom of the MDF-and-walnut piece is still perfectly flat
  • Measure & cut the trapezoidal MDF panels for the top and bottom
  • Cut the veneer pieces for the top and bottom

Three of the four pieces were simple trapezoids of walnut veneer, cut about 1/4" larger than the MDF surface, and so very quick to prep. However, the top had the five pieces of veneer joined together to form the principal element of the design, so I spent a lot more time cutting this out precisely. As I cut each piece, I verified that it would fit seamlessly with the previous pieces cut so far, and then used painters tape to temporarily hold the pieces in place.

However, the painters tape would not work in the vacuum press: though it peels off quite easily under ordinary usage, when clamped under 1000# of pressure for a few hours, some of that adhesive transfers to the wood and is very tedious to remove. So once the cutting was complete, I then used veneer tape - very similar to brown kraft paper tape - to keep the set together.

  • Veneer the solid walnut field of the bottom of the top piece and the top of the bottom piece
  • Trim - via a router with a flush-cut trim bit - the edge of that oversized veneer
  • Route out the back edges of the top & bottom pieces so that the back - attached as the last piece - can fit flush inside to give the piece additional stability and strength
  • Cut the three uprights (left, center, and right), and route out the outside edges of the left and right uprights
d Uprights Routed.jpg

This detail - which you can see at right here - came about in discussion with the client after following up with the template in detail. In particular, the angles and some of the lengths written on the template did not perfectly align with the angles and lengths of the template. Which were correct? We decided to follow the template, but in case there were minor deviations - or the drywall bowed out - I would a) route out the sides so that if the cabinet needed to be sanded down to fit, there was much less material to sand, and b) provide 1/4" radius quarter round solid walnut trim pieces for the top to allow for the opposite possible error, that the shelf was too small. Fortunately, the concern ended up being moot: the shelf fit perfectly requiring neither further sanding nor the quarter round.

  • Install the drawer slides on the bottom of the shelf - much easier to do precisely now before the top gets permanently attached
  • Assemble - via glue and screws - the uprights to the top and bottom, making sure the screw heads are below the surface of the MDF
  • Cut and install the drawer slides

  • Use wood filler and sand paper to make those countersunk screw holes disappear; now the “interior” of the shelf looks like solid walnut
  • Veneer the top of the top, and the bottom of the bottom

This was my "oh shit" moment in the assembly. The veneer glue I use has roughly a 20 minute "open time" - that is, I need to be applying the clamping pressure within twenty minutes of mixing the glue or I run the risk of the glue not holding. This is more than enough time for a small piece, still easily manageable for the unassembled top and bottom, but a bit more rushed for the outer surfaces of the assembled piece, both because the piece was heavier and thus harder to maneuver in the vacuum bag, and also because the top had to be placed precisely so the "joints" of the four walnut borders intersected with the corners of the top.

So, I was scrambling a bit, but breathed a sign of relief when I closed the bag and flipped the pump switch at about minute 15. The bag started contracting as expected, I started to clean up the mixing bowl, ... and then...


The vacuum bag burst! And while you can think of this as just a giant ziplock bag, they're a bit more expensive: this one cost $300!

The sharp corners of the trapezoid, combined with the thickness of the assembled shelf, popped the bag, as the vacuum press stretched the material across the edge. This isn't a problem for simple panels - like the unassembled trapezoids - because that stretching is only over about 3/4", and the polyurethane bags have more than enough give for that. But they don't have enough give for a 7" thick shelf!

In retrospect I should have put some spacers in the bag, or skipped the bag altogether, but I didn't have time to think through it now or even find the hole: I had about four minutes left of glue open time! Fortunately, I had plywood laying around already cut to about the size of the surface, heavy woodworking cauls handy, and enough bar clamps to clamp down on something that size. Not quite as ideal as a vacuum press, which provides far more even pressure over the entire surface, but - unless I wanted to potentially start over with cutting the outer veneers and lose a day or two sanding down the glue that would dry on the surface, I made do with the equipment I had on-hand.

Fortunately, it indeed worked out pretty well. Now we have a delicate piece of furniture with veneer / finished surfaces on the exterior, which means work has to proceed much more carefully as I can no longer sand out or as easily repair any blemishes that I might introduce as I move the piece around.

  • Trim - via a router with a flush-cut trim bit - the edge of that oversized veneer
  • Make the drawer boxes with poplar & walnut-veneered lauan bottoms
  • Cut and install the drawer slides to the drawer boxes, notching out the bottom rear rail of the drawers
  • Cut and attach the drawer faces to the drawer boxes
  • Cut and install the back
  • Finish with three coats of spar polyurethane
  • Pack, ship, and wait!

The crate alone was about 20 pounds; fortunately, the size and weight of the crated furniture fit just within FedEx's limits, so I was able to drop it off at my local carrier without too much hassle!

OK the title of this post was a little misleading - there were more than ten steps, and while a few of them were easy, most were a bit more involved. Nonetheless, I hope this gives you a better sense of what's involved in designing and delivering a custom piece of furniture, and so when you talk with a craftsman about their trade, there's a lot more that happens behind the scenes in delivering a beautiful finished piece than just a little sawing and gluing!

Other Commissions

Since the beginning of the year, I've done a handful of other commissions, including:

  • A pair of modern replacement drawers for an antique heirloom cabinet
  • A solid walnut shelf for a boat house in Emeryville
  • A set of 24 oval oak mirrors for a carousel refurbishment at the Spectrum Center in southern California
  • An entryway tray featuring purpleheart, walnut, and maple

Is yours next? I'd love to hear about a project you're considering!

Shop Tour: Part IV - Cutting & Carving

David WertheimerComment

Probably the last for a while in new workshop highlights, as - while there's always more or larger equipment to add - my shop is essentially out of space! Every wall has either tools hanging or a large machine pushed up against up; even all the ceiling space is claimed, between wood storage, a platform for my CNC, and air handling equipment!

Finding space to build those large commissions or occasional kitchen cabinet jobs that come in is a battle, so unless, or until, I move to a larger shop, pretty much any major tool that comes in will be only to replace something going out!

CNC Milling and Laser Carver

One of the things I've been eyeing for a while is a CNC carver. However, very few of my current designs would benefit from it, and part of me feels like it's "cheating" to use a machine to do the cutting and carving for you.

However, I was finally won over by the realization that it actually opens up a lot more capabilities, rather than replacing what I currently do "by hand". And even more specifically and immediately, by my need to make a clock "body" from the solid block of wood that I hope to start with for the Nixie clocks I've been working on.

Let me back up first: what is a CNC Mill, often just CNC for short? CNC stands for "computer numerical control" - imagine a wood cutting head that can move left and right, forward and backward, and up & down with incredible precision. That would be a three-axis (x, y, and z) milling CNC. That wood cutting head is typically a router, into which you can place different size and style carving tools. Or if you replace that router with a laser, you have a CNC laser, great for cutting more delicate materials or doing light engraving.

3-axis vs. more axes machines? For the technogeeks among us, the more axes, the more degrees of freedom over which the machine can move to carve your item. 3-axis machines let you cut and carve two dimension objects, as well as what are called "2.5d" - basically, by using a cutting head that always points straight down, you can cut really complex shapes, so long as all the pockets can be reached from straight above. As soon as you want to cut pockets that can only be accessed from the side, or another angle, you need more axes.

A 3-axis machine can also typically be modified so that one of those axis becomes rotational, making it essentially a computer controlled lathe, opening up even more possibilities such as carving 3d faces or columns, but still not quite true 4d or 5d geometries. This is a great article describing all the different axes, or these pictures may help you visualize.

3-axis CNC mill can do the design on left, but cannot reach the "undercuts" in the geometry on the right.

3-axis CNC mill can do the design on left, but cannot reach the "undercuts" in the geometry on the right.

A CNC lathe, converted from a traditional 3-axis XYZ CNC.

A CNC lathe, converted from a traditional 3-axis XYZ CNC.

This wood Transformer can only be done with a true 5-axis CNC; note the angle of the carving tool, which is a 4th axis.

This wood Transformer can only be done with a true 5-axis CNC; note the angle of the carving tool, which is a 4th axis.

A three axis machine typically has X, Y & Z movement, but one of X, Y, or Z can often - with extra hardware - be converted to A, B, or C, giving you a - say - A, X & Z machine to do CNC lathe-like carvings.

A three axis machine typically has X, Y & Z movement, but one of X, Y, or Z can often - with extra hardware - be converted to A, B, or C, giving you a - say - A, X & Z machine to do CNC lathe-like carvings.

A 3-axis CNC can easily cost thousands (or tens or hundreds of thousands) for large commercial or industrial machines. But with the maker movement, consumer grade machines - especially for those willing to do some assembly and configuration themselves - have recently become affordable. So I added an X-Carve 1000mm (about 3 feet square), with a removable Opt Lasers 6w laser, to my shop.

I'm still in the process of setting it up; though the machine itself has been built for nearly a month, I need to finish the torsion box, the automatic ballast for the ceiling lift, and the laser power supply, which I'll detail in future blog entries.

But here it is, in all it's glory! This is mounted on a retractable ceiling lift so it can easily get out of the way. But that lift has only two cables - one in the middle of the left and the right sides, rather than one in each corner - so I also need to build in a balancing mechanism so that the platform doesn't tip too far to the front or back. Also, check out the silver brackets on either side that allow for a higher-than-normal gantry to carve extra-thick surfaces (2-6" deep); this also means I need to insert a perfectly flat and smooth spacer - or torsion box - for when I'm milling normal-depth surfaces (0-4" deep). In future entries, I'll talk about each of these, as well as the laser - see the laser mount on the left of the yellow DeWalt spindle in the middle.


In a future entry, I'll also provide some more detail about my first few milling projects, but here's a little preview of what I plan to carve out first.

Body for Nixie clock, to mill out of a solid walnut and maple

Body for Nixie clock, to mill out of a solid walnut and maple

Miter-Fold Blade

This "miter fold" blade is really nifty, cutting a slotted V-groove in a board but not going all the way through, leaving just a tiny bit of wood remaining so that you can essentially just fold the wood to create a solid joint with a little glue.

While it allows me to make boxes really quickly from just a large flat single piece of wood that both allows for quicker construction and really cool and guaranteed continuity of grain over the joint, my more immediate use of it is to make an even better version of my simple shelves. I'll be trying out a few new designs here that now, which this blade, become much easier to make.

Miter fold blade profile...

Miter fold blade profile...

... and blade output

... and blade output

One of the shelves  that will benefit from the blade for the right angles

One of the shelves that will benefit from the blade for the right angles

The other shelf  that will benefit, ... but I also will be trying a few variations on this shelf which now become much easier with this blade

The other shelf that will benefit, ... but I also will be trying a few variations on this shelf which now become much easier with this blade

Compound Bevel Sliding Saw

Since I have such a nice table saw, I've never considered getting a radial arm saw for my woodworking. But I recently helped a friend with a small remodel that included cutting and installing crown molding, and suffice to say, that is a PITA to cut correctly by hand with nothing but a plastic miter box. Given that I'll be starting in on another remodel for myself soon, I figured I'd give in and get something to help with these construction projects, a compound bevel sliding saw.

While it's been great for those projects, I didn't expect it to be quite as handy in the shop for my wood working. But having had it for a few months now, I can't imagine how I got by without it! My table saw isn't that great for cutting a few feet off a long plank in that it requires me to push a 8 or 12 foot long board, weighing 30 - 80 pounds, through the blade, and it requires me to make sure there's enough clearance around the saw.

But with this new saw, it's always set up to cut across boards, and also much easier as the blade slides, rather than the wood. Plus, with a 12" blade - vs. the 10" I have on my table saw - I can tackle thicker boards and blocks, for instance, easily slicing down the 4" thick glue-up I made for a custom project.


Shop Tour: Part III - Furniture

David WertheimerComment

I had thought the shop was full before, what with wood stacked on the floor and all the wall space covered with machines. But creative reuse of space has allowed me to invest in a few new tools to expand my capabilities, which I'll cover in the next two issues.

Since I had the key woodworking tools already (see Part I and Part II), these are more specialized tools used less frequently, but that allow me to create even more unique pieces and furniture. Some of these will get one (or several) posts in the future, delving into both the nitty-gritty of the tool, and some of the pieces I've made with it, but until then, I'll get into some of the motivation for each bit of equipment, and of course, what it is.

Veneering Equipment

While all my small pieces are made with solid hardwoods, occasional larger furniture grade pieces I build are veneered. I'll confess I started as a veneer luddite: "Sure, veneered furniture can be cheaper because you can use crappy interior wood and cover it with a nice sticker, but all real furniture is made with solid wood".

But first: Why Veneer?

My naïveté here was dead wrong on several counts. First, veneer has a long history, dating as far back as the ancient Egyptians, over 5000 years ago (source).

A prototype coffee table base made of multiple pieces of hardware, joined only with glue, cracked by moisture and temperature variation - see more details  here .

A prototype coffee table base made of multiple pieces of hardware, joined only with glue, cracked by moisture and temperature variation - see more details here.

Second, veneered pieces are necessary for many designs. Typically, veneered furniture is built with a more temperature-and-humidity stable underlying base - such as with medium density fiberboard (MDF) - so that it will have a much longer life than similarly constructed hardwood furniture. You can see an entertaining story and pictures of an example of this from someone who started from a similar place of naïveté as myself here.

Or, if you want a thick shelf - some recent kitchen cabinetry I bid on called for a 2" thick shelves - even though solid piece of lumber might be available and may be within the your budget, it may be too heavy to easily wall-mount. A veneered torsion box (i.e.: hollow-core construction; more on these in a future edition) may be a much better way to go.

Sure, well-made tenon-and-mortise construction or dovetail joints will last forever. But if you're not going to the trouble of those, or don't want the style of those, you're left using glue, biscuits and screws. Yet you still need to consider wood movement with a larger piece, so the easiest way is indeed with unattractive but stable MDF, and then by making it look nice (or amazing) with a veneered surface.

Third reason to consider veneers: you can use a far wider range of woods, far more affordably, and get the appearance of far wider boards than are commercially available.

If there's no waste and the boards are perfectly sized, this table would cost about $70 of solid wood in oak (as pictured here), $200 if walnut, $400 if zebrawood or wenge, or $800 if teak. Keep in mind 1) there is waste from board sizes not being perfect matches to the furniture you're building, 2) there's hardware costs, and - most importantly - 3) there's labor and shop costs. Veneers make those more expensive wood finishes possible more affordably, as well as opening up all sorts of unique designs, as well as making the finished piece more stable to environmental changes, which is critical if the joints and construction doesn't allow for wood movement.

If there's no waste and the boards are perfectly sized, this table would cost about $70 of solid wood in oak (as pictured here), $200 if walnut, $400 if zebrawood or wenge, or $800 if teak. Keep in mind 1) there is waste from board sizes not being perfect matches to the furniture you're building, 2) there's hardware costs, and - most importantly - 3) there's labor and shop costs. Veneers make those more expensive wood finishes possible more affordably, as well as opening up all sorts of unique designs, as well as making the finished piece more stable to environmental changes, which is critical if the joints and construction doesn't allow for wood movement.

For some price comparisons, a square foot of 2" thick rough walnut is approximately $19 at my local distributor (or $8 for one square foot of 1"), but wenge or zebrawood is twice as expensive as walnut, and teak is twice again. So a 1" desk similar to what I just made of solid oak for a client would cost - for the wood alone - at least $200 per desk if walnut, at least $800 if teak, albeit only about $70 with oak. But with veneers, almost any wood would be achievable with about $100 or so of raw material (albeit with a lot more labor with veneers).

So if you want to feature more exotic wood grains, the only way to do it affordably is with veneers. This is also where the cheaper (and sometimes not so cheap) manufactured furniture comes in - sometimes that "veneer" may not actually be wood, but rather, its a simulated wood plastic laminate, or even just a cheap sticker. But if it's a real wood veneer, it will still give you warmth and range of color and grain.

Finally, you can do beautiful things with veneer that you can't do with hardwoods, such as this amazing cabinet done by Scott Grove, an award-winning woodworker; this piece was also written about in detail in his book, Advanced Veneering & Alternative Techniques.

Scott Grove Cabinet.png

Finally, the Veneer Toys!

With the motivation for veneering clear, let's get into the necessary - or at least very useful - for it I recently added to the shop.

Vacuum pump: As the name implies, this produces a vacuum, but not for cleaning. Rather, it's a stronger (but typically lower volume of air flow) than a vacuum cleaner. A veneer is just a big thin sheet of wood; to attach it to the MDF, you use a thin evenly applied layer of glue. But you need to evenly clamp that veneer to the substrate while it dries.

The vacuum pump enables you to apply even clamping pressure across a large piece. Basically, you put the glued-up veneered panel in a big plastic bag, attach the vacuum pump to the bag, and turn it on. With a vacuum inside the bag, the weight of the entire atmosphere above pushes down on the veneer - you can typically get the equivalent clamping pressure of up to 1800 pounds per square foot. And unlike a giant mechanical press - it works just as well for curved shapes as flat surfaces, so long as you have a big enough big!

The Excel 5 vacuum pump I picked up.

The Excel 5 vacuum pump I picked up.

Wendell Castle's  massive mechanical clamping press. There are hydraulic and other types of automated presses as well, but vacuum is the most common in a small shop.

Wendell Castle's massive mechanical clamping press. There are hydraulic and other types of automated presses as well, but vacuum is the most common in a small shop.

Of course, in addition to the pump, you also need some giant plastic bags that can attach to the pump, open at one side to insert the thing you're clamping. But these are not particularly interesting to look at when not in use, as they're just giant sturdy ziplock bags.

Edge bander: While the vacuum press will allow you to veneer a table top, it isn't that great for the side of a panel; a more specialized tool comes in handy here that allows you to apply an "edge band" of veneer. Basically, you use a heat-activated adhesive on a roll of veneer, and then some tool to apply even heat and enough pressure to bond the veneer.

A larger shop that does a lot of this might have a full-sized floor mounted tool; at the other extreme, many a piece have been finished with your common household iron and lots of care. I added something in a middle, a dedicated handheld tool from Grizzly. It'll still take some practice, adjustment, and care, but I look forward to using it on my first piece early this year.

The handheld edge bander I now have, with a roll of banding. This can apply rolls as wide as 2", which come in just about any wood species (as well as a variety of melamime colors).

The handheld edge bander I now have, with a roll of banding. This can apply rolls as wide as 2", which come in just about any wood species (as well as a variety of melamime colors).

A floor-mounted edge bander far beyond the reach (and needs) of my current shop!

A floor-mounted edge bander far beyond the reach (and needs) of my current shop!

Giant Clamps

The six foot clamps are taller than my dust collector!

The six foot clamps are taller than my dust collector!

I earlier spoke about bar clamps and how critical these are for any shop. But my shop previously maxed out with 24" clamps, with just a pair of 4' clamps. Well, this ain't really any new and exciting technology - sometimes you just need a bigger version of the same thing!

I picked up four 6' clamps to allow me to complete the pair of commissioned solid oak desks. At about 15 pounds each, they're tough to maneuver, but when you need them there's no way around them! The joint on the top is a standard dovetail, but the shelf immediately below the top of the table is joined to the legs via biscuits, and thus needed a lot of force clamping the legs to the shelf while the glue dried.


Dovetail Jig

A dovetail is a very common and traditional woodworking joint that gives a wide range of appearances and is incredibly strong. It's best explained with some pictures.

dovetailjigs_illustration 1.jpg

While these can all be cut by hand - and traditionally, have been! - I'll confess I do not have the patience (nor anywhere close to the skill) to do that. Fortunately, they can be cut quite easily with a router, a specialized jig, and specialized cutting bits for the router. Though there's many dovetail jigs on the market, I opted for a very flexible Leigh jig that allows you to create not only the more traditional dovetail joint, but also some really unique more curvy joints Leigh calls "isoloc" joints.  Look for these isoloc joints to be featured in some coming hardwood clipboards I have in process.

Examples of the unique "isoloc" joints that accomplish the same joinery effect as a dovetail, but with a more organic form.

Examples of the unique "isoloc" joints that accomplish the same joinery effect as a dovetail, but with a more organic form.

While I've already used the dovetail jig on the table I built above, I neglected to get good photos of the finished product, but you can see the joint on this practice box I built.


Perfect Valentine's Gift

David Wertheimer2 Comments

Looking for the perfect gift? Check out these novel bulbs in a silky-smooth polished walnut lamp. In early November, I came across these bulbs that folks seemed to love so much that I could hardly keep the lamps in stock!

Roses, birds, sunflowers, love, and peony metal sculpture bulbs with walnut base

Roses, birds, sunflowers, love, and peony metal sculpture bulbs with walnut base

I just finished a batch of the lamp fixtures, and hope you find them just as cool as I did! You can get the lamps - with any of these five bulbs - here.

More Info

These are fluorescent bulbs, filled with argon or neon gas.  The metal sculpture "filament" inside is coated with different phosphors to produce the different colors. When off, that sculpture is just black, or black and white.

They use 3w of power, run at 120v - standard US power - and are rated at 1000 hours. And they're easily replaceable - I'll provide a link to the distributor with the order. Though these bulbs work best on full power, all the fixtures have full range dimmers so that you can later replace with any dimmable bulb as well.

Amazing Installation Technological Art

David Wertheimer2 Comments

My regular readers have probably observed that I am a huge fan of things that combine technology and art in novel ways. This issue will be dedicated to a event my boyfriend and I attended mid-December at Pier 70 in San Francisco, co-hosted by The Midway, Pier 70 Partners, and Marpi, where that sort of thing was on display.

It felt a little like what some of the artistic installations I imagine Burning Man must have, but without the sand, hours-long drive, or the thousands of dollars of investment it would take to attend the event.

I'll confess: between the beverages we imbibed and the music we enjoyed, we didn't have too many (or really, any!) in depth conversations with the artists or creators, but I'll share a few photos and videos, and brief descriptions of what I understand these creations to be, and I welcome anyone's further thoughts on the exhibitions.

Laser and Fog


This was quite simple in idea, but very well done in execution: a laser illuminating a single "layer" of fog (provided by a nearby fog machine), so that the complex shapes and air currents can be visualized.

Lit-Up VW Bug

There ain't too much more to say about this one. It's a vintage VW Bug. With lots of lights on it. In some sense, not particularly sophisticated, but certainly attention grabbing!

Dancing Avatars


Have you ever wanted to be rendered as a dancing dinosaur, or as the Rock Monster from Galaxy Quest? Or dance against a psychedelic background that changes every time you swat at an imaginary globe hanging just about your head? A pair of installations enabled exactly this, by combining the Microsoft Kinect sensor with some clever software (and taking advantage of the great DJs in the background, and plenty of alcohol-fueled participants).

Rotating "Screen"

Though the physical implementation was quite clever and far beyond my skill set, in some sense these rotating arms with full color LEDs was not in itself particularly original. Though much larger in size and color palette, I had a toy version of this from RadioShack in the early 90s. However, the artist paired his far more sophisticated version with some pretty amazing software which he custom built, allowing him to start with an image or an abstract geometric pattern, and then morph it gradually in a variety of ways creating a mesmerizing display that looked like a circular TV screen - a screen that might lop off your arm should you run into it!

Rotating Picture.jpg

Building as Art

The pier itself was an impressive but dilapidated WWII-era corrugated steel building - more history here - worthy itself of being photographed. But one installation took advantage of a projector and custom-built software to highlight the steel trusses and beams supporting the structure, integrating the art and it's location in a novel way. I've added a few exterior shots from the evening as well so you have a sense of the environment.

And One Parting Thought...

Holiday Gift Edition

David Wertheimer2 Comments

OK this is probably a little late to come in with some of these holiday gifts, but I've always thought the best gifts are those that are both really cool and yet at the same time, things you would never get for yourself, these three items deserve a special mention. OK - maybe I might get myself a gift this season, and pick up one of these!

Levitating Lamp: Flyte

Well, I guess it is a desk lamp, so it isn't totally useless. This piqued my interest as a combination of a using electromagnet force to levitate (and spin), and electromagnetic induction to power the lamp without wires, packaged beautifully in something that looks nice enough to go on a coffee table or in a nice office.

Levitating Lightbulb.png

Admittedly, this is by no means a completely unique product - you may have seen cheap versions with the levitating piece for years on Amazon or in the in-flight Sharper Image catalog. However, in my humble opinion, upgrading it from cheap plastic to a wood (veneer) definitely ups its classiness.

Of course, there are similar beautiful designs available for a levitating planter, bonsai tree, "crystal" lamp, and all sorts of similar products. The prices range from $40 for the globe in the picture below, to $350 for the lamp on top. This is definitely something to consider for the person who already "has it all".

Floating Shelf: RockPaperRobot

If your budget is in the $350 range, and you know the recipient is in the market for a small shelf (and the more affordable shelves like this and this that I build aren't in the running!), check out RockPaperRobot, a Brooklyn firm with a floating shelf, and some other really amazing furniture as well.

RockPaperRobot is an engineering and design company specializing in shape-shifting and connected furniture. ... Celebrating the wonder of physics, our invention ethos draws inspiration from nature to create pieces that are as much experiences as they are objects. Our work redefines traditionally static stuff into dynamic platforms that reflect our appreciation for increased functionality, applied technology, and individual style.

Though just about all their pieces are really novel and worth checking out - such as a full-size kitchen table that stores like a piece of art on the wall, for those who suffer compact living in San Francisco or elsewhere - the one that really caught my attention is their floating shelf.

It is enabled by carefully-positioned rare earth magnets that provide the force to repel the cubes, counterbalanced by the steel rope to keep the cubes in place. (Yes, all these pieces I really admire feature embedded rare earth magnets as a core component of their functionality, including the Sisyphus sand plotter of Bruce Shapiro featured earlier).

And while the engineering alone is pretty cool, of course you want to be able to display it in your home. The one that really caught my eye has a beautifully-done continuous grain walnut veneer - but it's also available in black, chrome, and other finishes.

Time in Words: QlockTwo

This one doesn't feature wood or even wood veneer, but is nonetheless a beautiful watch (or wall or nightstand clock) that looks like a mysterious piece of art when not lit up. It tells the time in words ... but rather than try to explain it in words:

If you look closely, you'll see that the text only get it to the nearest five minute interval, but it has some very intuitive ways to narrow that to the minute, and also to represent seconds, as well as the date.

Credit to my brother for introducing (and gifting me with) one, and to a fellow mentor at the iMentor organization where I volunteer who works at Frog Design and introduced me to the other two.

Nixie Clocks, Wall Sculptures, & More!

David Wertheimer2 Comments

As the summer festivals have slowed down and I've gotten some breaks between commissions, I've had time to work on a few new unique designs.

Wall Art

I enjoyed making - and showing off! - the textured wall hanging, but I wanted to do something even bigger that could be a perfect mantlepiece, or perhaps go above a headboard.

Thanks, George, for the photo!

Thanks, George, for the photo!

I had just started sketching a few simple geometric patterns when I visited a remodel-in-progress of a friend in San Francisco's Laurel Heights; though they had yet to refinish the floors, I was blown away by the workmanship in the solid-oak original hexagon-patterned hardwood floor.

Thus, we have this first triptych, highlighting the rich contrast between maple, wenge, and walnut. Cutting and fashioning this into each hexagon gave me newfound respect for the workmen installing that floor, as I presume it was done with far fewer power tools when that house was built over 80 years ago!

And on a similar theme, I built this square triptych, with the same woods.

Check both of them - and the "Lenticular" textured piece as well - in the store here

Table Lamp

I had started the woodworking for a table-top lamp back in early March, but it sat half-finished since due to a lack of knowledge of the compact lighting parts with which to complete it. This is the second time I need to give credit to Konrad Jarausch of Sunlight Inside, who pointed me in the right direction both for the form factor and a few suppliers of high-power low-voltage compact LED lights. (Check out that earlier post about LED lighting here).

I paired that with a large heatsink and satin-finished acrylic tubing to create this light, which can be configured from two to five layers for a desktop lamp 6" to 15" tall. You can see this in the online store here.

Twisty Lamp 5 - b.JPG
Twisty Lamp 5 - d.JPG

Nixie Tube Clock

Several customers have expressed interest in a "Nixie" clock. The first time I was asked, I didn't know what I was, so I started reading up.

Excerpted from Bad Nixie:

The name Nixie is expanded from Numeric Indicator Experimental (NIX); it is a product of the mid 50's to early 90's and is no longer manufactured. Nixie tubes are the predecessor to the light emitting diode (LED). They look like vacuum tubes, but are in fact a form of neon lamp filled with a mixture of Neon gas and a small amount of Mercury or Argon. Inside the tube are ten successive formed wire digits as cathodes, and a wire mesh anode. Each cathode digit and the common anode has a pin at the bottom of the tube. To light a digit you simply apply voltage between the common anode and the digit pin; when energized the digit illuminates with the warm glow of neon.

Though these tubes are no longer made new, there are probably hundreds of thousands of "new old stock" - which despite the apparent contradiction, is not a typo. These are decades-old spare of warehoused inventory that was never used, and in many cases, in the original packaging. The old stock is primarily located in Eastern Europe, though there are a few American supplies as well.


I've been unable to find a lot of pictures of original hardware using these, though I did come across this calculator - which apparently had a fairly short sales life due to the small time window before the introduction of the much cheaper LED-based display. However, now they show up primarily in artistic and steampunk clocks, or occasionally in a unique one-off pieces like this impressive Sudoku game!

Though I hope this doesn't linger unfinished nearly as long as the lamp I just completed, it may take a while to finish: the circuit boards are from UK; the Nixie tubes just arrived from Ukraine. I just completed the assembly of the first circuit board, though it still needs some troubleshooting. And I'll need to design and machine a (wood, of course) enclosure that has tight tolerances for all the switches and tubes.

Perhaps this is the final motivation to get a CNC, which will also allow me to carve some of those mazes and geometric patterns? Regardless, as I make progress here, I'll share a few updates & photos.

My partially-assembled circuit board with IN-8 tubes

My partially-assembled circuit board with IN-8 tubes

Political Rant and Call to Action

David Wertheimer2 Comments

Your regularly scheduled programming on art, woodworking, lighting, and the like, has been replaced with a brief rant on our current politics and a call to action for increased civic engagement.

There's a range of political discourse and views with which people of good conscience can disagree, and that can form the basis of animated or even heated debate. But the lack of decency, and disinterest in demonstrable fact and science of the current administration makes me scared for our future and for our democracy.

Here's the rant... feel free to skip past this section...

Economic grabs by the 0.1% disguised as tax "cuts" and "unburdening" business. Demonizing science and scientific discourse, and transforming "career bureaucrat" into a slur when its this expertise and knowledge that keeps, among other things, our drug supply safe and rivers clean. Undermining civil rights for minorities of all stripes, whether via attempting to ban transgender in the military, gutting Congressionally-authorized federal oversight of police, or trampling on voting rights of disenfranchised communities. Singleminded focus on coal as the world shifts in other directions for both economic and environmental reasons. Appointment of agency heads whose professional mission prior to running said agencies was the dismantling of that agency [Pruitt] - or who have zero knowledge in that agency [Carson]. Reveling in divisiveness and holding campaign rallies, all for ratings and press coverage, without even attempting to provide a moral backbone, showing at best, disinterest in, and at worst, contempt for, uniting the nation.

I could continue with more statements, each one of which you could find a hundred well-written articles by those with deeper knowledge than myself, great historical context (such as this blog written by my good friend, Noel Cilker), and more specific thoughts on how to respond.

... continue reading here.

At a lunch in late September, a friend and former colleague asked me what I'm doing about my concerns, which reminded me that, in addition to my nightly YouTube dose of Trevor Noah, Stephen Colbert, and Seth Meyers, we should make sure we're engaging in more constructive activities, and encourage our friends and family to do the same.

So put your time and money out there to make the world a better place! If you are already engaged in one (or many) ways, thank you! If you're not, there are so many different ways to engage that can best make use of your time, energy, skills, or whatever you can offer up.

Engage with your community directly via Meals on Wheels delivering food and social interaction to homebound seniors. Help build homes or provide necessary repairs for disadvantaged communities with Habitat for Humanity. Participate in domestic microlending via an online platform such as Kiva. Amplify your voice with your local congressman or senator with an appeal to refocus on the interests of the 99%, environmental protection, civil rights, etc. Donate to the disaster relief efforts of the recent hurricanes in Puerto Rico or Houston, or to the SPCA. Do a spring cleaning of your old clothes and give them to Goodwill, or your dusty and useless foreign coins to Unicef, or your battered old cell phones to the National Network to End Domestic Violence.

There are so many worthy organizations into which to channel your energy, your money, your unwanted but still useful possessions. And for hundreds of more volunteer ideas, check out Volunteer Match.

What am I doing?

Since the beginning of this year, I have directed thousands of dollars towards net new solar projects across the U.S. - much of this enabled by your business, as I've committed to spending 10% of my revenue in this way. Additionally, I've just installed 4kw solar system on a building I own, and am investigating installing about 20kw more in Arizona.


I have volunteered about 50 hours this year with Habitat for Humanity and Grid Alternatives to build houses and install solar for low income communities (and about 250 hours last year). I am mentoring a student who aims to be the first in his family to make it to college.

And for something a little more unique, I have shared a few hundred of these cards with friends and family.  Want one? I'm happy to send you a few for free - just reach out on email - or if you want several, they're available inexpensively here.

I'd love to hear about unique (or not-so-unique) actions you've taken to make the world a better place, to take a stand for decency, and to oppose the destructive and self-dealing directions of this administration. Share in the comments below, or feel free to reach out directly.

Edison Bulbs & LEDs

David Wertheimer2 Comments

I covered the basic questions about the Edison bulbs I use a few months ago in this blog. But the bulbs I focused on then are incandescent, and I've gotten a pang of guilt when customers ask me why I don’t offer LED-based Edison bulbs with the light fixtures I sell, given my parallel focus on clean energy and energy efficiency.  The short answer I used to give is that there just is not yet an attractive LED Edison bulb. But is this true?


Lighting consumes about 10% of electricity in the United States, and about 15% worldwide. If you haven't already, replacing old-fashioned incandescents with more efficient compact fluorescents (CFL) or - even better, LEDs - is one of the simplest and cheapest upgrades you can do to reduce your own energy load and thus, reduce carbon emissions (and save a few bucks).  For example:

  • 40w incandescent can be replaced by an 8-12w CFL or a 4-9w LED; running 3 hrs a day for a year, at average California electricity rates (18c/kwh), an LED will save you over $6/yr per bulb. If it's in a location that runs 10 hours a day, that becomes $22/yr
  • 100w incandescent can be replaced by a 23-30w CFL or a 16-20w LED; similarly, if replaced with an LED, running 3 hrs a day, that will save you $16/yr or at 10 hrs, $54/yr.

Indeed, nearly every light bulb in my own home is an LED, and in a recent remodel I completed, I used all LED-based lighting fixtures so that the home would be more efficient from the get-go. Those who read my earlier blog about my commitment to renewable energy both on a personal level with Branching Out Wood - 10% of my revenues are directed towards net-new clean energy projects - and with another business I started, Branching Out Solar, know that take I take this seriously.

All four of these bulbs are LEDs, reducing this lamp from consuming 160w to about 16w. Or if you run it 3h a day, that will save you $28/yr!

All four of these bulbs are LEDs, reducing this lamp from consuming 160w to about 16w. Or if you run it 3h a day, that will save you $28/yr!

Back to LED Edison bulbs: what's actually missing, and if you are willing to sacrifice a little, can you use the bulbs that are out there now? Jumping to the punch line, there actually are good enough Edison LED alternatives for many - but not all - of the fixtures, and due to your questions, I now have a limited quantity available at shows. Or if you are ordering online and would prefer these bulbs, reach out on email, and I'll work with you to see if they're available for the lamp your interested in.

For the nitty gritty on what you might have to sacrifice, and some side-by-side comparisons, keep reading below.

What’s Needed For a Good LED Edison Bulb?


The “warm” light one usually gets from a traditional incandescent light bulb is around 2700K, and fortunately, this is one attribute that LED lighting can check off.  LED bulbs are available in 2700K (and both warmer and cooler temperatures as well).  In fact, some more-advanced bulbs allow you to control the temperature, or automatically adjust the temperature based on other environmental factors.

One of a variety of color charts available comparing different reference points and manufacturers

One of a variety of color charts available comparing different reference points and manufacturers

For the geeks among us, according to Wikipedia, “is the temperature of an ideal black-body radiator that radiates light of a color comparable to that of the light source”. For the rest of us, just think that as that campfire cools down, you go from yellow flames to glowing red embers.  Or where it gets super hot, you might see some blue.

Color Rendering Index (CRI)

This indicates how well a light source is at rendering color and how well subtle variations in color shades are revealed by that light. It is an index that measures how evenly across the visible spectrum the light bulb produces light, or if you want to go really deep, you can see the ten step process for measuring it here. The max score is 100, with halogens and incandescents receiving that score; at the other extreme, those notorious sodium vapor lights that are the most common street light get a negative score.  A good score for an LED used to be 85, but now 90 or even 98 is available; anything above 90 is pretty darn good, so LEDs can check this off as well.

Representative spectrum coverage by a particular supplier of high-CRI LED lights; daylight is shown with the dashed line, and the high-CRI light is shown with the heavier white line just below it

Representative spectrum coverage by a particular supplier of high-CRI LED lights; daylight is shown with the dashed line, and the high-CRI light is shown with the heavier white line just below it

cri - pencils.jpg
cri - apples.jpg

Warm on Dim

When you dim an old fashioned light bulb, it gets less hot. When it gets less hot, it emits less light, but the light it emits is also at a lower temperature, producing warmer (more reddish) colors.  This happens “automatically” due to the way an incandescent produces light, via heat; the light is actually secondary. When you dim an LED, however, the color stays roughly the same, since the color is a property of LED rather than of the heat produced. This was considered the “last frontier” of LEDs back in 2013, but has since been conquered with a variety of products that combine multiple colors of LEDs in a single bulb and change the mix of colors as the power to the lamp decreases.

However, note that while this is a feature that is available in many LED lamps, by no means is it available in all - the typical dimmable LED bulb that you might pick up at Home Depot or Lowes does not have this feature, as it adds complexity and thus cost to the product. And - at least as of now - no Edison filament LED bulbs have this. You can, however, find this feature in some bulbs at speciality lighting stores or online. 

Filament Appearance

The real beauty of the Edison bulb is the decorative filament, whereas most LED bulbs have frosted glass (or plastic) globes to hide the actual light producing elements. However, there are a few attempts at creating an Edison filament with LEDs:

Ikea's Nittio bulb

Ikea's Nittio bulb

  • Ikea’s Nittio bulb: Kudos to Ikea for selling only LED bulbs as of the end of 2015; this was a bold move that has had a real impact. The Nittio has a pair of LEDs hidden in the base that light up a plastic filament - you can see a tear down of the bulb in this video. Though it this nifty implementation provides a lot of flexibility for future filament styles, it falls short on many other properties; it’s not even dimmable (so forget “warm on dim”).
  • Stranded Edison LEDs: Several manufacturers, such as Bulbrite, have developed Edison LEDs that look much better when on, are dimmable, with a high CRI, but they appear a bit clunky close up and when off. Their limitations are that they do not (yet) have warm on dim capabilities, and many - like some dimmable LEDs in general - are a little finicky with certain types of dimmers.

So They Do Exist!

Those bulbs right above look pretty darned close, so I went out and purchased a handful in different styles, meeting these properties:

  • 40w equivalent (380-450 lumens), but consuming only 3-5w per bulb
  • CRI above 80, but in a few bulbs, above 90
  • Dimmable
  • Color temperature of 2400-2700K

The Good News

The right-most bulb is incandescent; the other three are LEDs. The difference in filaments and type is quite visible.

The right-most bulb is incandescent; the other three are LEDs. The difference in filaments and type is quite visible.

As an accent lamp, the relatively high CRI - though not as good as an incandescent - looked pretty good, though the noticeably thicker "filament" of the LEDs is clearly visible when the lights are off, and to a lesser extent, when they're off.

The LEDs all worked with the dimmer switches I use, which was a pleasant surprise given all the warnings and incompatibility lists I've seen.

An unexpected advantage of the LEDs over incandescents is that, at very low brightness, an incandescent sometimes gives off a barely perceptible high pitch whine, while the LEDs are completely silent. Who would have thought noise would be an observable property of a lightbulb?! And for most people, and in most environments, this would be a non-issue. But as a desk lamp in an otherwise silent room, on a low brightness, you may actually hear the incandescent!

And of course, in consuming less power, the LEDs all produce much less heat.

The Bad News

The LEDs all lacked the "warm on dim" feature, where incandescents in general, and Edison bulbs in particular, excel. I tried to capture this difference in these pairs of photos, though it did not come out as clear as I had hoped. And while I noticed it because I was looking for it, you may not be as cognizant of this. In talking this through with a few customers at the San Carlos show I did in early October, it wasn't something they noticed or were cognizant of.

The LEDs had a slight flicker as you rotate the dimmer, though they do not flicker at all when the dimmer is set at a particular level. Perhaps more relevant, however, is that LEDs can not get as dim as incandescents - when set below a certain level, the LED just shuts off whereas an incandescent still gives a nice glow.

LEDs were only available in a more limited set of shapes and styles compared to the full range of incandescents. For instance, I could only find about ten LED bulbs that met the minimum criteria I listed above, whereas incandescents have closer to twenty. And the half-reflective bulbs great for some of the desktop lights are available in silver, but not gold.

Even further limiting the range of shapes for those particularly keen on their lighting, the ten I found had a color range of 2400 to 2700K, but that 300K color difference was noticeable (but not jarring) in the multi-fixture lamps when the bulbs were side by side, whereas there is no color difference between adjacent styles of incandescent bulbs. So if you're particularly finicky about these sorts of things, you'll want to make sure all the bulbs you get are exactly the same temperature, reducing the variety of bulbs you can get for a multi-lamp fixture further.

Finally, of course, there's the incremental cost of about $5/bulb over incandescent. As noted in the intro, that pays for itself in electricity savings, but it raises the cost of some of my fixtures to a point that makes the lamps unaffordable. For instance, this lamp, with six bulbs, would cost $30 more, but if used 3 hours a day, would save you over $130 per year.

The Verdict

LEDs are pretty darned good, but - largely due to lack of full range of shapes and higher initial cost - not yet perfect for me to include them on every sale. However, I will start stocking a few and making them available for an extra $5/bulb at shows, and using them myself in the art festivals (since readers of this prior blog entry know that keeping the lights on at the booth is an ongoing challenge for me).

Want them in a lamp you want to order online? Just email me for a custom listing.

Thanks to my customers for challenging me on this point. Your questions both gave me the inspiration to dig deeper here, and the impetus to change my practices in making LEDs available with my products.

And further thanks to Konrad Jarausch for initiating me to the the very basics of the technical vocabulary for thinking about comparing LEDs and incandescents. For more on what he’s doing, check out Sunlight Inside, which develops and sells nifty tabletop lamps that automatically generate the light color that you would be seeing outside if only you weren’t stuck inside all day, for all sorts of health and well-being benefits.

Computer-Generated Circular Art

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Computer-Generated Circular Art

In place of the regularly scheduled blog about handcrafted woodwork, this week I'll share some details about a recent project in enabling a computer to create "art" automatically.  From the recent "Artists That Inspire" post, you may recall my description and admiration of Bruce Shapiro's Sisyphus creation: a robot that draws beautiful geometric patterns in a sand bed embedded inside a coffee table.  Before he launched his Kickstarter to make this commercially available, I thought I'd take a stab at creating one myself.

For a sense of what this Sisyphus thing might look like, check out the photos here, or go to

One of the many pieces I had to develop was software that could automatically generate continuous line circular art.

I developed two types of continuous line drawings: circular mazes, and geometric patterns. Though I no longer have any need to draw this in sand, I can imagine these becoming future wood creations, perhaps as trivets, or as toys. The mazes in particular can be customized, with versions that could stump the most persistent puzzle master, or that would be of interest to those with a little less patience.

I recently dusted off the software in developing a proposal for a mass-customization product for a potential corporate client, and thought I'd share some of the images and puzzles that came out of it.

If you're mathematically inclined or enjoy algorithms, the details below might interest you. Or just take a gander at the images and let me know what you think!

Circular Mazes

Start at the red dot on the perimeter and end at the center; like any good maze, there is exactly one solution.

Did you have fun trying to find the solution?  (If not, you can find the solutions here). Would you find it fun - or maddening - to do that in a toy with a marble?

How to Draw a Maze

These mazes are randomly generated - the only inputs I provide are the outer diameter, the inner diameter, and the number of concentric rings. The logic to create a maze is actually quite simple: you can read about a variety of approaches here. A circular maze only required rethinking the concept of what maze “cells” are adjacent to each other.

Astute readers may wonder if there isn’t a fourth input, how many cells are in each ring, or at least, how many cells are in one particular ring? While this could be an input, I decided instead to define this somewhat algorithmically, so that the cells in that innermost ring are roughly squarish, and that there are a power of four cells (i.e.: 4, 8, 16, ....). I'll skip over the geometric details of this, but it goes back to highschool geometry and trigonometry, secants and radii and the like.

Then as you go to outer rings, as the growing circumference means you can squeeze more squarish cells into that ring, the number of cells periodically doubles. Note that the fact that outer rings can have more cells than an adjacent inner ring makes tracking cell adjacencies for the maze algorithm a little more interesting, though it doesn't change the underlying approach.

Geometric Patterns

These patterns are also randomly generated. Would this make an interesting trivet or decorative wall hanging that you might enjoy?

These are created in one of two ways. The pattern on the left is created by starting with a simple polygon, like a hexagon. But rather than simply drawing it, each of the lines is rotated slowly and with a pen that gradually drifts outward, so that that shape is "fully" drawn, it's actually left slightly open.  Then the the next hexagon starts where the last one left off, but repeats those same transformations, so it's rotated slightly more, and slightly larger.

The pattern on the right is slightly more complicated: imagine a spiral, but then, instead of drawing it with a straight line, draw it with a repeating geometric pattern, such as part of triangle. In both cases, the pattern is random: the simple shape to start from, how tightly packed the spiral or rotating shape is, etc. And so you have an infinite array of geometric patterns.

Drawing with Two Pens

Because these were intended for a polar plotter, that plotter could actually have a pen on each side of the arm, drawing with two pens simultaneously, allowing for an even greater range and complexity of patterns. In each of these triplets of pictures, there’s the single pen version as above, and then two multi-pen versions. The second pen is drawn in red. Can you figure out the pattern relating each of the two multi-pen versions?

If you imagine a polar plotter with a pen on each side, the second pen can be mechanically joined to the first pen in one of two ways:

  1. Both pens could keep the same distance from the center, so that when the black pen is near the center, the red pen is also near the center but on the opposite side; or
  2. Both pens could be a fixed distance from each other, so that while the black pen is at the center, the red pen is at the outer edge.
My (unnecessarily complicated) polar plotting mechanism, sporting two independently controlled "pens"

My (unnecessarily complicated) polar plotting mechanism, sporting two independently controlled "pens"

Bruce Shapiro's Sisyphus far more elegant production-manufactured polar plotting mechanism

Bruce Shapiro's Sisyphus far more elegant production-manufactured polar plotting mechanism

Think any of these patterns would make interesting projects? Or have your own randomized drawing approach to share? I'd love to hear about it from you.

Artists That Inspire

David Wertheimer2 Comments

There are a number of artists and technologists whose work I admire or from which I have drawn inspiration and ideas. I’d like to take a moment out from my regularly scheduled post to highlight a sampling of them.

Modern Cellar: Tim Krablin & Melliza Taipe


I’ll start with a company who speaks the most closely to both my style and my craft: Tim Krablin and Melliza Taipe of Modern Cellar. They built beautiful, predominantly solid walnut, small and large wine racks and wine cellars, and developed quite a following with projects commissioned by both vintners, custom remodeling, and art festivals.

Unfortunately, however, they closed up shop in 2010. I first stumbled across their products at a furniture store in San Francisco in 2007, and have since recreated one of their wine racks from memory, as well as developed a few things that draw from their style.

The Art of Motion Control: Bruce Shapiro

Bruce Shapiro has spent many years developing “the art of motion control”, applying this typically industrial technology to artistic expression.  Have you ever seen a robotic arm doing a ribbon dance? Or pictures created by the carefully timed release of bubbles in test tubes? He’s your guy.

I’m impressed by the way he brings together multiple domains to create unique and in-motion art: there’s clearly the artistic and creative vision, but there’s also the highly-mathematical programming, there’s the physical elements of valves and motors, and tying those pieces together. And of course, there’s the craftsmanship of “making it beautiful,” hiding all the technology in an artful way.

I first saw Bruce’s work at the San Mateo County Maker’s Faire in 2015, where he was exhibiting Sisyphus. This is essentially a table that supports a bed of sand, under which is hidden a rotational plotter that drags a steel ball through the sand via magnets to draw mesmerizing geometric patterns in the sand. Though at the time, he had built just a few of these for exhibitions, in late 2016 he announced a KickStarter with a $50k goal; it achieved $1.9m in pledges of which I was one of the first twenty to commit.

Inspired by Sisyphus, before he launched his KickStarter, I took a stab at building a version of it myself. I developed software to create nifty randomized geometric patterns for a rotational plotter, learned the Arduino system and the basics of a Raspberry Pi to control it, and started procuring stepper motors, power supplies, gears, and the like from all over (well, mostly China) to try to make it a reality. Let’s just say I’m glad Bruce decided to commercialize it - he saved me a lot of time and money, and I have confidence that his piece will display far better in my living room than what I was developing.

Phuze Design: Orfeo Quagliata

I came across Orfeo Quagliata’s work at a show in San Francisco about a decade ago. Though he works in a number of mediums - and even studied furniture design at the California College of the Arts - the pieces that I was particularly impressed was his glass work, and in particular, the “barcode” collection. However, all his work is just amazing, typically lighting uniquely formed glass to highlight the interplay of colors. He’s also a partner in Phuze Design, which highlights several glass artists, each with a unique and impressive style.  If only I had the space (and the budget)…!

Though I’d be the first to admit that they pale in comparison, my backlight glass block nightlights are inspired by Orfeo’s work.


Is there an artist that inspires you, that bridges amazing design and excellent craftsmanship, perhaps with a streak of modern technology, whose work you admire? If so, I’d love to hear about them!