Getting Geeky with Wood Properties

Last Friday, I left you hanging with this little chart:

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It’s a rough workup of some wood strength data that I’ve been gathering and analyzing, since it has become clear that I’ll have to make some deviations from accepted practice in the wood selection for my Windsor chairs. Of particular concern is finding a suitable substitute for the leg stock. Tradition dictates (and modern makers all seem to be in agreement) that the premier wood for Windsor chair legs is sugar maple.

They have a strong argument – sugar maple compares favorably among native timbers for its strength characteristics. This is important, because the most highly regarded Windsors – both today and in the past – feature legs and posts turned to diminutive dimensions that simply wouldn’t hold up in a lesser wood. However, a look at some strength tables clearly demonstrates that, while sugar maple is certainly no slouch, it’s not at the top of the pack, either.

Terry Kelly
Sugar maple is used for the delicate turnings. Notice the dramatic curves and the diminutive dimensions of the coves. A strong wood is required to stand up to the abuse that a chair faces. Photo Credit: Terry Kelly

Let’s consider two different measures of wood strength: modulus of elasticity (MOE) and modulus of rupture (MOR). MOE can be referred to as “stiffness”. It’s a fairly straightforward measurement that simply asks: How much force is required to bend a clear section of wood of specific dimensions by a certain amount? In other words, imagine holding a popsicle stick; how much force does it take for you to bend it by 1/4″? This will be determined by the stiffness, or MOE, of the wood.

MOR can be understood as “breaking strength”. The question it asks is: How much force is required to bend a clear section of wood of specific dimensions to its breaking point? Going back to the popsicle stick, we’re simply asking how much force it will require for you to break it in your hands.

There are many more measures of strength, but these are two of the most commonly used and easily understood. There is a definite correlation between MOE and MOR. Woods that have a high stiffness also tend to have a high breaking strength. However, there are some deviations from this general rule that we’ll find to be important. Also, both measurements are correlated with density – the denser the wood, the more likely it is to be stiff and strong. Ideally, however, we would like to build with the lightest possible wood that will provide appropriate strength. No use making our chairs heavier than they need to be, right?

Alright, that’s enough of the backstory. Let’s have a look at some juicy graphs. There’s a lot going on here, so I’ll try to walk you through (please note that you can click on the graphs for a larger version). The top graph plots MOE (stiffness) against density*. Each dot represents a single tree species. As you move from right to left, density increases, and stiffness increases as you move from bottom to top.

Wood Stiffness

Wow, lots of trees here. In the version below, I’ve highlighted some species that are at least as stiff as hard maple.Stiffer WoodFirst off, there are some obvious surprises (even to me, and I have a Master’s degree in wood properties). Look at Douglas-fir and the yellow pines: lighter and stiffer than sugar maple. So should we Southerners be building our chairs out of longleaf pine? Well, not so much, as we’ll see when we examine the MOR graphs. I was also surprised to see sweet birch and yellow birch perform so well. Same density as hard maple, greater stiffness. These species pretty much overlap the same range as sugar maple, so it doesn’t help me out, but it begs the question: Why aren’t these birches regarded as highly as sugar maple? (Do keep in mind that these two are head and shoulders above all other birches – don’t try turning Windsor legs out of paper birch or river birch or you’ll be sorely disappointed).

There are some less surprising candidates as well. Hickory is off the charts, head and shoulders above most of the crowd. Oak of many different species (both white and red) aren’t too far behind. However, notice how variable the oaks are. Some of them actually rate pretty poorly. And poor bur oak – the density of sugar maple with the stiffness of black willow – yikes! I almost wonder if that’s a data error or just a poorly selected test sample. Black locust fits in somewhere amongst the hickories and oaks.

Now, oak and hickory and locust are all perfectly nice woods, but they do have one common shortcoming: they are all ring-porous. That is, they all have alternating layers of big-pored wood and small-pored wood that correspond to the growing seasons. What we want for a spindle turning is a nice even-grained, diffuse-porous wood (maple and birch are common examples). Because of the evenness of their texture, diffuse-porous woods tend to be less likely to splinter while turning, so they can hold crisp beads and fillets and be polished to a smoother surface straight from the tool. To be precise, hickory is actually a semi-ring-porous wood, meaning that it fits somewhere in between oak and maple – and it would probably be a perfectly fine wood to use in a pinch – but I’ve turned enough of it to know that it’s no joy to turn, unlike maple.

So what is left?

Well, there are two interesting candidates remaining. Live oak is one. I know, I just got done saying that oak is a ring-porous wood, unsuitable for the crisp details of a baluster leg. There is one exception to that rule, and it’s live oak. Live oak is not a wood that woodworkers run into frequently, so it would be easy to overlook the fact that it falls into its own category, separate from red and white oak. It’s stronger than most any oak, but that strength comes with a lot of extra weight and hardness. It is not an easy wood to work. But it’s also a diffuse-porous hardwood, and it’s the most common tree on the island where I live. Very interesting. There are some problems as well, though. Live oak is a nightmare to split. And it has very prominent rays that might cause problems with chipping when turning. It seems to be worth a try, though.

Live oak end grain
This live oak is diffuse-porous – it doesn’t have the bold annual rings of red or white oak. However, notice the prominent rays (those white streaky-thingies). Those might cause some problems when turning (click to zoom in).

Finally, the most interesting candidate of all: Persimmon. It’s stiffer and harder than sugar maple. It’s diffuse-porous (okay, some references will call it semi-ring-porous, but the pores are not as big and prominent as, say, hickory). And I know from experience that it splits easily and turns beautifully. Seriously, it takes a world-class polish straight from the tool. Turn it once, and you’ll never forget how well it works. I daresay that persimmon might be the silver bullet – the one wood that we Southerners have that could surpass sugar maple in every measurable characteristic (except density, but I think that’s a minor issue; it certainly won’t affect appearance). The only problem: it’s not the most common tree to find in the dimensions needed for Windsor chair legs. Oh, I’ve seen it 4′ in diameter and 120′ tall, with nary a branch for the first 70′. But that is the exception, rather than the rule. I’m going to give it a go at some point, though. Mark my words. And if I still have any readers at that point, you’ll be the first to know how it turns out.

Alright, stiffness isn’t the only trait we’re interested in. No, we don’t want our chair legs to flex excessively, but the more critical virtue is making sure that the suckers don’t break. That’s where breaking strength (MOR) comes in.

Wood Strength

One thing I notice right away is that the relationship between density and breaking strength (R2 = 0.80) is much tighter than the relationship between density and stiffness (R2 = 0.52). Also, notice that the softwoods (southern yellow pine and Douglas-fir) that seemed so impressive on the stiffness scale have dipped into mediocrity on the breaking strength scale. Add to that the fact that softwoods don’t turn worth a crap, and you have your answer as to why we don’t use conifers for chair legs.

Stronger Wood

Beyond that, the placement of the species has changed very little. The hickories are still the leaders of the pack. Black locust, black and yellow birch, persimmon, and live oak are still sitting above sugar maple in breaking strength. The red and white oaks don’t seem to perform quite as well as they did in the stiffness test, but the change is minor. So whatever conclusions we drew from our examination of MOE would seem to hold true when we consider MOR.

Wow. I hope this post hasn’t turned out too dry, but I fear that it has. Density, stiffness, porosity…these aren’t usually the things that gets a woodworker’s blood pumping. We like pretty colors and striking grain patterns. Most craftsman-made furniture tends to be over-engineered to such a degree that it makes nary a difference whether we choose pignut hickory or eastern redcedar to built that blanket chest or dining table. It just has to look good!

Windsor chairs are different. The grain needs to be straight and plain and boring. Straight grain means ultimate strength. The shapes – rather than bold wood color or showy grain – provide the visual interest. And the dimensions are pushed to the extreme, so the wood (and the joints) must accommodate. You will be need to be equal parts craftsman and engineer – and I don’t know if you’ve noticed, but that suits me just fine.

*All data for this series was adapted from this US Forest Service Publication. Density, MOE, and MOR measurements were all taken at 12% moisture content. I will be posting a link to the raw data that I pulled from the publication, as well as the graphs included in the article, in the form of an Microsoft Excel file.

UPDATE: The wood property data and the primary source have been added to “Wood Properties Resources” in the menu bar at the top of the page.

Of Timber and Tenets: A Yankee Chair in the Deep South

Windsor chairs are not exactly the iconic furniture forms in the Deep South that they are in New England. I’ve tromped around antique stores in Maine and seen enough lovely old Windsor chairs (and woodworking tools) to be jealous of my northerly woodworking brethren. The more humble ladderback is a much more typical find in a southern antique store. They’re easier to build and require a smaller toolkit, so it’s no surprise that the ladderback was the common chair in the more rural South.

rustic ladderback
Southern ladderbacks are typically austere, with simple turned or shaved posts and rungs and a seat woven from hickory bark or white oak splints.
Williamsburg Ladderback
Ladderbacks could be fancy, too, with elaborate turnings and rush seats, but the fancy ones (like this one from the Colonial Williamsburg collection) tend to come from New England.

Because the American Windsor style evolved primarily in New England, they came to rely heavily on the woods that were readily available in the North. Sugar maple is hard and strong, but turns beautifully, making it perfect for the delicate baluster turnings of the legs and rungs. White pine is light and soft and carves easily, allowing the development of more shapely seat designs. Oak, ash, and hickory are strong and bendy, ideal for thin, elegant spindles and curvaceous steam-bent backs.

All of those woods are common in New England – and even as far south as the southern Appalachians – but once you set foot on the red clay of the Piedmont, white pine and hard maple are suddenly nowhere to be found. There are substitutes, of course. Tulip-poplar grows well into Florida and as far west as Louisiana. Plenty of Windsor chairs are made with yellow-poplar seats. But they tended to be less shapely than their pinaceous counterparts. Poplar is 25% denser and commensurately more difficult to carve.

Sugar maple is even tougher to substitute. You can use red maple, of course, which grows from the east Texas swamps to the coast of Newfoundland. But conventional wisdom says that soft maple is conspicuously weaker than hard maple, so you’ll have to nix the delicate turnings in favor of a bulkier design. Beech is another option here, but it must be sawed rather than split, so grain runout is a problem if you aren’t careful.

Fortunately, most of the South is replete with oak, ash, and hickory, so the upper half of the chair isn’t so much of a problem…unless you live in the Really Deep South – the longleaf sandhills, the pineywoods and pocosins, the laurel thickets and maritime forests near the coast. If you live there, you’re basically screwed. Oh sure, there’s oak to be found, but it’s scrub oak* or live oak. Scrub oak is useless except for firewood, and live oak is great for ship-building but less exciting for chairmaking. Of course, I live on a little barrier island on the northeast coast of Florida, right in the heart of the chairmaking deadzone.

Boo-hoo. Cue the sad piano music:

OK, I’m not really complaining. I love where we live. And I’m certainly not here to pass on apocryphal dogma. I’m here to question everything. I’m the recusant woodworker, after all. Folk wisdom is nice and usually contains more than a crumb of truth, but what happens when we look at things from a scientific perspective? I am a wood scientist by education (though not profession), after all.

I intend to investigate some southern woods with a fine-toothed comb to see if might be possible to beat those snooty Yanks at their own game (I kid, I kid. It would be much easier if I could source sugar maple and white oak and white pine locally!)

Here’s a taste of the research I’ve been working on:

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Some of the results are surprising and encouraging. TBC…

*As a dendrology buff, I feel compelled to note that “scrub oak” is not a species, but rather a group of species, prevalent in the southern sandhills region. It includes turkey oak (Quercus laevis), blackjack oak (Q. marilandica), bluejack oak (Q. incana), and sand post oak (Q. margaretta), which all share a similar, scrubby growth habit and feature poor-quality wood. Great for wildlife and firewood, though!

Productive Procrastination

On Sunday, I finally rid my shop of three pieces that have consumed my time and shop space for the last month. You already know about the sassafras kitchen table. I also had a couple of tripod tables kicking around my shop the whole time.

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Cherry on the left, river birch on the right.

They’re based on a design from the Shaker Village of Pleasant Hill near Harrodsburg, Kentucky. Kerry Pierce has an excellent book on the furniture from this village – it was probably my most-referenced woodworking book for several years. The table on the left is cherry, like the original. I made it back in 2011, and it’s one of my favorite pieces – simple and attractive, requiring only a paucity of time and materials. I can easily make one in three evenings.

I brought it back into the shop because the finish needed some work. When I originally built it, I finished it using just oil and shellac. The finish looked nice at first, but somehow, an open bottle of rubbing alcohol was left on the top…shellac dissolves in alcohol…you can figure out the rest. There’s been a disfigured blotch on the top for a while now that needed to be repaired. I sanded down the top and re-finished the whole thing with a few coats of lacquer.

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My enviable finishing room.

While I had the table in my shop, I decided to build another in river birch. I have a couple 15″-wide boards of slightly-figured birch that were just begging to be used, so I submitted. It was only a few evenings, right?

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Once those projects were out of the way, there was really no excuse to avoid the Windsor chair any longer. My plate was clean. I still wanted to build a new shavehorse, but there was no rush, since I won’t get the material to make the upper half of the chair until Thanksgiving. (My old shavehorse – a Jennie Alexander design – has seen plenty of use over the last decade, but it’s uncomfortable for long sessions). My dad, who lives in North Georgia, has set aside a nice white oak log for me to use for the crest rail and spindles. Coastal Florida is a bit of a desert for Windsor chair woods.

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The fact that it almost fits my 3-year-old daughter is probably a good indication that this shavehorse is really too small for me.

Everything from the seat down – the legs, stretchers, and the seat – can be built using the tools and materials that I already have. No excuses for not getting started. So, of course, on Monday evening I walked into my shop and immediately put off the Windsor chair for just a bit longer.

Horse 003
Is procrastination still bad if you’re building cool things?

Instead of pulling out some poplar for the seat, I scrounged up a maple board and began building my new-and-improved shavehorse. And of course I chose the most complex (but also the most excellent) design around – Peter Galbert’s “Smarthead”. I figured I could knock it out in two evenings. I thought wrong. Hopefully one more evening to go…

I’m afraid the Windsor chair has become a bit of a white whale for me. I’ve been reading and dreaming about it for so long, I’m a bit scared that my creation won’t live up to my dreams. Am I the only one who does this? Is it normal to put our dreams on hold in a ruthless attempt to keep them pure? It’s uncomfortable to think that we might not be up to the task. But it’s heartwrenching to find out for sure. That applies to a lot more than just Windsor chairs.

When I first started woodworking, I was fearless. My first dovetails were cut with a Stanley flush-cut saw and a crappy 1″ chisel that I re-ground into a 1/2″ chisel so it would fit between the tails. I don’t want to think about how much time I spent at the grinder to pull that off. They weren’t perfect, but I wasn’t expecting perfection. I was just happy that they fit together. As my expectations were elevated, though, so too did my trepidation.

Not in every case, of course. I’ve built a lot of tables. The first piece of furniture I built was a coffee table. The second piece was my workbench, which is still just a table. The third and fourth pieces were end tables. The fifth was another coffee table. I can’t even count the number of tables I’ve built, of all shapes and sizes. They don’t scare me a bit. Once I have a design in mind, I just walk to my lumber stacks and begin picking out the material. I reach for my saw and and my square and I start cutting. There is no mystery and no reservation.

But a Windsor chair is a different story…Multiply the number of joints by 10. Multiply the complexity of the angles by 100. Multiply the importance of an aesthetically and ergonomically sound design by 1000. I’ve come to view them as the apogee of woodworking engineering and design. And with my respect comes no small amount of unease.

These thoughts stirred my mind and kept me awake as I lied in bed last night. Today, I decided put the thoughts on paper pixel, and then put them to rest. I know I’m up to the task, and the only person I have to prove it to is myself.

No more dreaming. It’s time to start doing.

“In with the New, and Out with the Old”

Song lyrics were running through my head as I rubbed down the final coat of lacquer on Sunday morning:

Down with the shine, the perfect shine, That poisons the well, and ruins my mind, I get took for a ride every time, Down with the glistening shine.

The Avett Brothers are right. Aerosol lacquer leaves a nearly perfect finish straight from the can, but even the “satin” finish is too shiny for my taste. To tone down that glistening shine, I prefer to rub it out with a green synthetic steel wool (Scotch-Brite) pad. You can use real steel wool, but it’s annoying because it disintegrates and leaves a mess.

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Before
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After

In addition to to reducing the plastic-y look that lacquer can give (not as bad as polyurethane though), rubbing out the finish vastly improves its tactile qualities. The fingers can easily see what your eyes can’t.

Unlike sandpaper, which always needs to be used with the grain when sanding the finish, the Scotch-Brite pad can be rubbed in a circular pattern. If you’re really feeling like a rebel, they attach quite nicely to the Velcro of a random orbit sander.

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The final step is a coat of paste wax. I’ve had one can that I’ve been using for at least 8 years, and it’s still not close to halfway gone. Paste wax brings back just a hint of shine, adds a bit of water-proofing, and further improves the smooth, tactile awesomeness of the finish. Rub it on lightly with a cotton rag, let it dry for about 10 minutes, and buff it off with a clean cloth.
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The layers of finish will continue to cure and harden for at least a month after the final coat is applied. I try to treat my furniture gingerly for a while after I bring it inside – we’ll see how well that works for a kitchen table in a house with two young kids.

After the paste wax was done, the table was ready leave my shop. Cue the next verse:

It’s in with the new, and out with the old, Out goes the warm, and in comes the cold, It’s the most predictable story told, In with the young, out with the old.

The old table was certainly warm and well-used.
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Complete with glitter paint:

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And watercolors:

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And plenty of dents and dings:

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My daughter was actually crying as I disassembled it to store in the attic. Fortunately, her sadness quickly shifted to delight as I brought the new table in and began to set it up. Unlike the old table, which overwhelmed the small space and made it difficult for two people to move around in the kitchen, the new table fits the space perfectly.

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Let’s just pretend that this is an attractive, modern showroom and not the outdated kitchen of 40-year-old rental house, shall we?

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When I began the project, I was mostly excited that I had a kitchen table design that would be quick and easy to build so I could move on to other projects. Now that it’s finished, I have to say that I couldn’t be more pleased with the outcome. I think the table looks modern, but not avant-garde. It goes nicely with our motley collection of kitchen chairs. We feel more like a family as we sit around this table, all facing one another and within an arm’s reach, rather than stretched out across a too-big table. It just feels right. And that’s a good feeling.

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If you’d like to follow the whole series of posts on designing and building this table, you can click here and start at the bottom. 

How to Calculate the Radius of a Circumscribed Circle of an Equilateral Triangle with Side Length (x) and Why You Should Care.

So, do I win the award the award for the most objectionable blog post title ever?

What? There’s no award? What a waste.

Well, anyway, one of my dear readers (and you are dear, trust me, I can count you on my fingers and toes) asked me about how I located the peg holes on the underside of the top of my sassafras kitchen table (from this post). The intuitive way would be to flip the table upside-down and set the base on top, then push it around until the distance from the point atop the legs to the nearest edge of the tabletop is equivalent for each leg.

equilateral
The tops of the legs form an equilateral triangle. Your mission, should you choose to accept it, is to mark the corners of a congruent triangle that is precisely centered on the underside of the tabletop.

That would work, I suppose, but it would be finicky and prone to error. As my reader surmised, there is indeed an easier, more precise, more elegant way. First, we just need to envision that the top corners of the three legs form an equilateral triangle. The length of the sides is easy enough to measure. In this case, it was 28.75″ precisely.

Let’s call the length of the side (x). If you recall from high school geometry, there is a fixed relationship between the length of the sides of an equilateral triangle and the radius of a circle – we’ll refer to the radius as (y) – that passes through all three corners (i.e., a circumscribed circle).

That relationship is: y = x (√3) ÷ 3

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Mmm…numbers. For the record: No, I didn’t remember this formula. I had to look it up.

So, we just plug in 28.75 for (x) and we get 16.598820…Let’s call it 16.6″. I don’t have a ruler that’s marked in tenths of an inch, so I just used 16 38/64 (16.594″). I adjusted my trammel to the radius and scribed a circle on the on the underside of the table (you can see it on the picture above).

Okay, now we have a circle of the proper radius that is perfectly concentric to the edge of the table, but we still need to accurately locate the three corners of the triangle. Well, that’s dead-simple now that we have a trammel set to the radius. Just pick a point on the perimeter and start “walking” the trammel around the perimeter, making a mark at each intersection. You should end up at the same point that you started at (or very close to it) with six equally spaced marks around the circumference of the circle, forming a perfect hexagon. Drill a hole in every other point, and there you have your perfect equilateral triangle.

hexagon
Mathematical constants are fun and useful!

So there you have it. Hopefully I made the process tolerably clear – it took far longer to write about it than it did to actually complete it.

Why Do We Aim For Perfection?

I’ll admit that I have a bit of a soft spot for crude antique furniture. I don’t mean crude in the sense that it’s poorly built or falling apart or left to rot for 50 years in a dank barn. I’m talking about the furniture that was built quickly and competently and well-used for a century or two, but without much consideration for the complete removal of surface blemishes and measuring marks. There’s something about the tool marks on a chair that connects me to the man who made it. Instead of seeing my own reflection in French-polished perfection, I see a window into another world.

Was the maker in a hurry? Was furniture-making his profession, or did he just build some chairs during the winter to pass the time before spring planting? Did he have a well-equipped shop or did he make do with a rough collection of tools? Did he take the time to sharpen his tools or did he press on with a plane that was well past due for grinding?

Every woodworker leaves a trace of his or her methods in one way or another, but in rough rural furniture, the questions and answers leap out at you before you even think to ask them. I was thinking of this after inspecting an old children’s ladderback chair that belongs to my niece. I sat in my brother’s living room inspected the chair for every tool mark I could find.

The chair probably originates from somewhere near the North Georgia antique shop from whence it was rescued. The paint color is a fantastic blue and red with stylized flowers on the back slats.

Children's Chair 1
Well-painted furniture only gets better as the years go by.

The real story is in the woodwork, though. The first surprise is the choice of the wood itself. This chair is made completely of yellow pine. It’s the only pine ladderback I’ve ever seen, and it probably only lasted this long because it was made for 30-lb toddlers instead of 200-lb men. Stranger still? The wood was riven (i.e., split from the log as opposed to sawed). That’s not unusual at all for chairs of oak or ash or hickory, but this is the first I’ve seen of riven pine for furniture. The riving marks are everywhere you look:

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There’s evidence of hatchet work as well:

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The flat spots on this foot appear to be the work of a hatchet. Also notice the grooves from the lathe work on the lower part of the foot. It appears the maker used a gouge instead of a skew chisel here.

The rungs were shaved with a drawknife, not turned. This is not unusual, but it’s interesting that the maker didn’t even attempt to make them round. They’re nearly square in cross section, with just the edges chamfered:

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Very crude rungs.

The mortises for the back slats appear to have been cut with a pocketknife – and they probably were. Apparently this was common practice in southern Appalachia as documented in the first Foxfire book.

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Notice the over-cut mortises. You can see where the knife scored the beads above the mortise.

Finally, a view from above. The maker didn’t even attempt to bend the slats – not surprising, since (a) yellow pine isn’t exactly known for bending well and (b) rough chairs like these were often made with flat slats anyway.

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The slats weren’t bent as they are in more refined (and comfortable) ladderback chairs.

In spite of (or really, because of) all of its flaws and asperity, I love this little chair. Who knows how many diminutive derrieres have rested in this seat over the years? Its current owner is certainly a fan – I caused quite a stir when I took the chair into the yard to photograph and joked with my 4-year-old niece that I would be using it to start a campfire.

As we poked and prodded the chair, I mentioned to my brother that I would find it hard to make a chair with the same kind of surface quality as this one, even if I made a reproduction. I know I’m not the only woodworker who shoots for a higher standard in my own work than I look for in an antique.

So what’s the deal, then? Why do we insist on such perfection in our own work while admiring the crude pragmatism of the old?

My brother, who is not a woodworker, but is one hell of a musician, offered an analogy that I found interesting. Apparently there was a bit of a trend recently in British rock to sound intentionally rough and unrehearsed – the instruments were left just a bit out of tune, the music was played a little sloppy, the vocals maybe not quite on key all of the time. The idea being that the bands were aiming for the nostalgic imperfection of the Rolling Stones, rather than the flawless polish of Rush.

It sounds like a good idea. I’d take the Stones over Rush any day, right? The problem, however, was that the music ended up sounding, well, contrived – at least, to fellow musicians. They wanted to sound soulful and natural, they but instead they sounded like they were trying to be imperfect.

I think it’s this idea of striving for imperfection that I take issue with. I’m afraid that my furniture would not resemble the brisk work of a competent professional, but the formulaic inconsistency of those godawful “handscraped” floors that seem to be popping up everywhere these days.

Handscraped floors
WTF? Whose hands did you scrape these floors with? Wolverine’s?

One could argue that the man who made this chair had more in common with a garage band than the Rolling Stones, and they would be right. The truth is, he wasn’t at the top of his game. There are far better examples of chairs in the historical record, with more attractive proportions and more careful surface finish. I don’t think it matters, though. Have a look at this blog post at Popular Woodworking if you’d like to see an example of an 18th century masterpiece complete with turning marks and tearout from riving. The blemishes are smaller and more discreet, but they’re still there, and I still try to avoid them.

I think it takes a surprising amount of skill to pull off this sort of historically accurate imperfection. Robin Wood can do it with his medieval bowls and spoons. Peter Follansbee can do it with his colonial chests and joint stools. But both of them have more than a couple of decades of experience working with traditional tools in traditional ways. I’m but a neophyte hack compared to those men.

What it boils down do, I’m afraid, is that I chase perfection to hide my own lack of skill.

We Interrupt Our Regularly Scheduled Poetic Waxing…

…to bring you a quick update on a project from the honey-do list.

My wife knows that I’m chomping at the bit to get started on Windsor chair, but she had a few requests before I get started. Numero Uno was to build a replacement for our kitchen table.

We like our kitchen table. It’s a big, beefy trestle table made from thick white pine. My grandmother bought it new in the 1960’s. It was well-built, but when I inherited it, the dark finish was gummy and depressing. I was too busy renovating a house to worry with fixing it. When my wife and I were married, one of her first requests (demands?) was to re-finish the table. We sanded it down to bare wood, painted the base with barn red milk paint, and oiled the top with linseed oil. We’ve shared many meals around this table over the last 5 years.

But, we now live in a small ranch house with a small kitchen, and the trestle table is 3′ wide and 6′ long. It’s just too big. A round table was requested, which should fit the space much better.

A table is a simple object. It can be built as quickly as you like, or you can dress it up with as much fancy joinery, carvings, or veneer as your imagination allows and it can take a year. For this project, my aim was workmanlike efficiency, but with a tolerable aesthetic appeal.

I began with a search of Google images, using a number of keywords. “Round Dining Table”. “Round Shaker Pedestal Table”. “Round Modern Dining Table”. “Round Tripod Dining Table”. “Round Modern Tripod Table”. Something like that, you get the idea. Each iteration was inspired by something that caught my eye in the previous search. I quickly latched on to one theme: a modern approach to a tripod base with the legs intersecting along X, Y, & Z axes.

Modern Round Table
This was the first table that really caught my eye. The interlocking “puzzle-joint” makes a minimalist, but visually interesting, joint. It’s just three intersecting planks, but the mind immediately wonders how it was made.
Modern Tripod Table
I liked this one as well. The maker chose a more interesting wood (looks like zebrawood to me) with a strong, straight grain pattern that echos the simplicity of the design. The glass top is appropriate for the alluring base, but I would like the table more if the legs actually intersected, instead of just criss-crossing alongside one another.
Interlocking Tripod
Finally, I found another glass-topped table, but this time with a base that includes some interesting joinery.
Tripod Joint
The execution is a bit loose, but I like how each beam seems to be embracing another. The wood appears to be beech.

I love geometric puzzles, and the final photo had me imagining how the joint fit together. A few minutes in Sketchup confirmed my suspicion that the basic joint was just a simple half-lap. I quickly settled on this design for the base of my table. Even though I don’t find it as visually striking as the first joint, I like the elegant simplicity  of its engineering. Unlike the first joint, this one can be assembled from whole timbers, rather than cutting and gluing up at least one leg (but if anyone thinks they can demonstrate a way to create the first table’s base using whole timbers, well, good luck…)

One thing that became apparent from my work in Sketchup was that the height of the table directly impacts the diameter of the top. If you want your tabletop at 29″ high (a usual height for a dining table), then you’re going to have trouble making it  much less than 48″ in diameter (and even this requires truncating the legs, such that they have squared-off ends, rather than ends that follow the plane of the floor and tabletop. Hopefully the Sketchup drawings make it clear what I mean by this).

So, I’ve settled on 48″ for the diameter of the table, but if I find that this is still too big for the space, then I can probably shave another inch off the radius without too much trouble. A bit of work in Sketchup yielded this model:

Sketchup Tripod

With a simple, 44″ half-lapped 3×3 as the basic component:

Leg

I can’t say that this is the prettiest or the most exciting thing I’ve ever built, but it meets the criteria that I had in mind when I originally set out to build this table: It’s visually interesting, expedient to build, and I already have the necessary materials on hand.

My Dysfunctional Relationship with the Windsor Chair, Part II

Part I

It was September 2005. I had just earned my Bachelor’s Degree in forestry from the University of Georgia a few months earlier, and I was jumping right in to my graduate classes. I don’t remember much from that semester, honestly, but one class that stuck with me was my Advanced Wood Properties and Identification class. It was one of the best classes I ever took, and it was taught by my major professor.

On the first day, the professor gave a fascinating lecture on the history of pernambuco wood, or pau do brasil (Caesalpinia echinata). The tree is native to Brazil, and once flourished along the coast in great abundance. Portuguese navigators realized soon after visiting the that the tree’s heartwood could be extracted to retrieve a highly prized red dye, and the race was on. Trees were harvested and logs exported to Europe by the millions. Excessive exploitation resulted in a precipitous decline of the valuable trees by the 18th century, but not before luthiers realized that the dense wood was ideal for making bows for stringed instruments.

A serendipitous combination of density and stiffness, plus the proper cocktail of natural extractives (the chemicals in wood that give heartwood their color, odor, and rot-resistance) make the wood unrivaled in its suitability for violins bows. Though the tree is now listed internationally as an endangered species, pernambuco bows still command a hefty premium to bows of lesser quality woods. The wood can only be harvested from trees that die naturally, which amplifies its scarcity and preciousness.

The lecture struck a chord in my mind – specifically, the idea of selecting a species of wood that is most perfectly suited to the task for which it’s used suddenly seemed quite shrewd and elegant. In the woodworking that I did at that time (mostly bowl-turning, and the occasional dovetailed box), there was really not much need to consider the properties of wood, aside from its appearance. I selected bowl blanks for their attractive coloration and grain patterns. It didn’t matter if the wood was light and soft (like boxelder) or hard and dense (like cocobolo). As long as it was pretty, I would turn it into a bowl. No big deal.

The lecture created, in my mind, fertile ground for a more thorough appreciation of the dignified simplicity of the Windsor chair. I believe I learned from Curtis Buchanan the rationale behind the diparate collection of woods found in the traditional American Windsor:

  • Sugar maple for the legs and turnings: Strong and dense, sugar maple can be turned to delicate proportions, yet still maintain the rigidity needed to support a sitter daily for a couple of centuries. Unlike similarly strong woods, it has small pores, which means that turnings can hold crisp details without chipping. Plus, it splits well, so getting straight-grained, riven wood, with simple tools, is easy.

    turning
    The delicate details of a hard maple leg. Credit: Elia Bizzarri
  • White pine or poplar from the seats: Sure, we could use elm like the masochistic Brits, but American chairmakers chose a soft, easily carved wood to make their shapely, comfortable seats. The wood has just enough give to lock the harder woods of the legs and spindles into place.

    seat
    A shapely shield seat in white pine. Credit: Curtis Buchanan
  • Oak, hickory, or ash for the rails and spindles: These ring-porous hardwoods split easily – perfect for creating long, impeccably straight-grained sections for the upper pieces of the chair. Splitting, rather than sawing, preserves the stregth of the wood, and makes for successful steam-bending, which allows the wood to be shaped to better match the countours of the sitter’s body. Additionally, all of these woods are strong enough to be whittled thinly, allowing the parts to flex for comfort, yet still retaining sufficient strength.
    crest
    Graceful spindles and crest rail in oak. Credit: CartersWhittling

    Equipped with this new understanding, I began to see Windsor chairs in a different light: no, the wood wasn’t selected for the boldness of its color, nor the flashiness of its grain. Each wood was carefully selected to create a strong, light, and architecturally refined structure, that also happens to be comfortable as hell to sit in!

My Dysfunctional Relationship with the Windsor Chair, Part I

I still remember the first time I saw a Windsor chair chronicled in a respectable woodworking publication. It was probably in 2005. I had just made my first major tool purchase – a lathe that still sits in my shop today – with my savings from a summer internship as a forester in North Carolina. I still didn’t have a shop, so the lathe sat in the carport in front of our house, alongside a deep freezer. There was only one electrical outlet in the vicinity, so plugging in my lathe plus my working light meant that the deep freezer had to be unplugged while I worked. On more than one occasion, I failed to plug the freezer back in after a lathe session (much to the consternation of my father). I’m pretty sure the cost of the rotten meat and vegetables approaches what I spent on the lathe itself, but let’s get back to the topic at hand.

I had a voracious appetite for woodworking magazines. My dad, though not much into woodworking himself, somehow ended up with a subscription to Popular Woodworking, and I greedily devoured every picture and word of every issue that made it to our house. I started buying issues of Fine Woodworking from Home Depot to sustain my appetite in between issues of Popular Woodworking.

My favorite section from that magazine was the Reader’s Gallery. It usually covered four pages and was filled with creative and virtuosic work that covered the breadth of the craft. There was rarely a piece that failed to take my breath away; even rarer was the piece that I felt would ever be within the scope of my abilities.

A decade later, I can’t recall many specific pieces from those pages, though I’m sure their influence still resides in my subconcious. But there is one piece that I still remember fairly vividly. It was a comb-back Windsor arm chair. Painted black, sitting proudly and traditionally, it seemed quite the contrast to the original and quirky forms that surrounded it. I remember reading the list of woods that comprised the stately seat: sugar maple for the legs, white pine for the seat, oak for the rails, and hickory for the spindles.

curtis buchanan comb back
The chair look about like this (Curtis Buchanan comb back)

I know what you’re thinking: It was love at first sight. I was taken aback, and it’s been my dream to make this chair ever since.

Well, no. Nothing could be farther from the truth. At the time, I thought that the blasé chair had no place within the pages of that magazine. Why would anyone combine such a motley assortment of woods, I wondered. Any then paint the fool thing?! Why not build it out of a wood that was worthy of such efforts? Cherry, walnut, curly maple? At that time, my attention was captivated by wood above form. I had no clue why anyone would use oak, pine, hickory, and plain maple to build a chair that could be deemed a masterpiece. And paint? Why, there was a special place in hell reserved for people who painted wood. Even bland and uninteresting wood deserved a clear finish! Didn’t it?

I think my feelings were, at that time, heavily influenced by the chairs that we sat upon at family dinner, from the very first spark of a memory in my toddler mind. They were Windsor chairs in fact, but not spirit. They were factory-made from solid maple. The seats were unshapely and uncomfortable. The spindles were too thick and didn’t give. Don’t even get me started on the shape of the comb. The finish was a sickly stain and varnish that couldn’t decide if it wanted to be brown or tan. The glue was failing on many of the joints, and the chairs creaked and wobbled and rebuffed my dad’s efforts to fix them with those stupid epoxy injection systems.

Bad Windsor Chair
They looked kinda like this. Please, cover your childrens’ eyes if you have any innocent young ones looking over your shoulder.

Thankfully, those chairs are long gone, but the memories stayed with me as I gazed perplexedly at the pages of the magazine.

Part II