At least, that’s my experience. Maybe that means I’m not very creative. Actually, I’m quite certain that I’m not very creative. I am analytical to a fault, and indeed, many of my blog series (The Name of the Grain and Woody Wednesday, for example) as well as my job title (Forest Resource Analyst) reflect that. Perhaps that’s why I naturally gravitate towards historical furniture forms. There is something comforting about building furniture in a tradition that incorporates the evidence of a thousand years of failures and successes. Why re-invent the wheel when it’s already been refined by countless generations of craftsmen more competent in their trade than I can ever dream of being?
More often than not, when I find myself departing from tradition, it’s to accommodate a special piece of wood that simply doesn’t fit into the classical canon of furniture forms. Such is the case with my current project. My dad asked me to build an end table. He already had the wood picked out for the top – a slab of white oak 15″ wide, 40″ long and 1-5/8″ thick. It’s a lovely piece of wood, cut from a crotch with plenty of flame figure – but it also has plenty of defect.
The wood was cut in a manner that is opposite from the way that a crotch would normally be sawed. Woods like walnut, cherry, and birch normally display the best figure when the crotch is sawed, as my old friend Tom would say, “like a pair of britches lying flat on the floor” – with each fork representing a leg. Oak, on the other hand, usually presents the best figure when the wood is sawed perpendicular to the customary orientation.
The problem with this method is that it includes the pith in every flitch. Anyone who has ever sawed their own hardwood lumber is well aware of the problems with the pith. The juvenile wood immediately adjacent to the pith often has a life of its own, bending and twisting as it dries. And the nature of wood shrinkage means that the odds are good that you’ll have cracks in any board that includes the pith. My dad’s slab was no exception.
Fortunately, the slab was large enough to salvage a sizable chuck of wood while completely discarding the pith. The result was an elliptical tabletop, 13″ wide and 24″ long.
The problem, at this point, was that I had very little historical precedent to work with for designing the base. Oval end tables – especially tables that utilize a piece this thick – are scarce. Now, this isn’t the first time I have found myself in “modern furniture” territory. I detailed my design process for my tripod kitchen table in the early annals of this blog. Basically, it involved typing some descriptive keywords into a Google image search, plucking out a few designs that I really liked, and modifying them to suit my preferences. In this case, however, Google was of no help, and I found myself starting from an empty slate.
So, I did the only thing a non-creative person can do in this situation: I sharpened my pencil and got to work. I started sketching stream-of-consciousness until I stumbled upon an idea worth pursuing. I’ll warn you, the process (or maybe just my sketching ability) isn’t pretty:
Most of the sketches belong exactly where they are: on the cutting room floor. But I thought that the sketch at the bottom right of the first page had potential, so I explored it further on a second page, playing around with the dimensions of the members as well as the horizontal and vertical proportions of the whole structure. I really liked the way the curves flowed through the joinery and the arch at the bottom reflected the ellipse of the top. I decided this design was the winner.
It was time to make full-size drawings – a step that I rarely take, but I felt that it was necessary to get a realistic idea of the proportions. My first iteration, with 3″-wide members, was a bit to heavy, so I revised the drawing to 2″ members. That looked right to my eye, and I was satisfied enough with this drawing to begin the painstaking process of animating the idea in ligneous flesh.
But as always, the ultimate question is not “Does it look good on paper?”
The now-ubiquitous Windsor chair has its roots in the simple, ancient stick-chairs of Great Britain. The Windsor chair is differentiated from other styles of chairs in that the seat plank serves the foundation for the entire the chair. The legs terminate in mortises below the seat, as do the spindles above the seat. Other historical forms of seating rely on the wood to serve merely as a frame for the seat, which could receive upholstery or woven reeds, bark, or cane.
The stick chair evolved into what we would recognize today as a “Windsor” chair in England in the early 18th century, and the form was soon exported to colonial America, where the chair grew in popularity to become the dominant form of seating. From its humble beginnings, the Windsor chair evolved into a dizzying array of different forms throughout the 18th century – all of them originating in Great Britain before making their way across the Atlantic – with innovation continuing on into the early 19th century.
Though there is a fair amount of variation in the arrangement of legs and stretchers below the seat, chairs are typically classified according to what’s going on above the seat. For a solid primer on the different styles of Windsor chairs in the 18th century, I would suggest this article by Nancy Goyne Evans, the woman who wrote the book on American Windsor chairs (literally).
One of the last styles to be developed during the 18th century is also one of my personal favorites – the continuous-arm. According to Evans, “Regarded today as a classic in Windsor design, the continuous-bow chair was developed in New York City about 1790. The sweeping profile of the bow is based on the French bergère chair, examples of which were produced at this date by local cabinetmakers. This is the only eighteenth-century Windsor pattern based on a non-English prototype, and it is the only Windsor design dating before 1810 introduced to the American market in a place other than Philadelphia.”
Given that Evans is such a widely respected authority on Windsor chairs, this statement has apparently carried some weight in the chairmaking community, because it is frequently repeated by chairmakers today. Witness Elia Bizarri’s remarks to Roy Underhill at around minute 1:20 in this video.
In fact, some have even taken it a step farther than simply stating the design originated in America; chairmaker Bob Dillon states on his website that the chair was “uniquely American, never appearing in Europe.”
And finally, some folks are frankly just somewhere out in left field with regard to this topic. Thomas Moser is undoubtedly a legend in the cabinetmaking community, but his website’s statement regarding the continuous-arm chair is more than a little suspect: “In about 1750, Rhode Island cabinetmakers came up with the idea of making the arm and the back of the chair from a single piece of hickory or ash, two types of wood that lend themselves to being steam bent and curved. While undoubtedly beautiful and comfortable, the Continuous Arm Chair took tremendous skill and patience to make, because of the need to form a compound curve with right angle bends.”
I don’t believe there’s a shred of documentary evidence that points to a Rhode Island origin for this style, and certainly not as early as 1750. But let’s return Goyne’s statement that the continuous-arm is a uniquely American form. Observe these two chairs originating from the tiny town of Yealmpton, England:
Looks very much like a continuous-arm to me.These chairs were recently sold at auction, being described as “Iconic Pair of ‘Yealmpton’ Continuous Arm Windsor Chairs”. I must thank the pseudonymous “Jack Plane” over at the fantastic blog Pegs and Tails for bringing this obscure style to my attention. He included a picture of the chairs in a post on English Windsors back on February 24 with the following description: “The chairs in figure 10 are of an egregious style peculiar to the town of Yealmpton in Devon which – whether for reasons of relative geographical isolation… or taste – thankfully didn’t pervade the country at large.”
Personally, I find the chairs quite charming, if a bit peculiar. I would assume that Jack’s objection to the pictured chairs stems primarily from the regressive style of the turnings and the somewhat overstated radial splay of the the over-sized spindles. They look almost like the spokes of a wheel compared to the more subtle splay of conventional Windsor chairs. I certainly find no fault with the design of the continuous-arm, which almost looks as though it could be plucked from these chairs and placed onto a New York continuous-arm and hardly a soul would notice.
A quick Google search will confirm that, indeed, this style of chair is well-associated with the history of Yealmpton, which begs the question: which came first? The styles are simply too similar to have evolved independently of one another. The earliest American continuous-arms date from around 1790. In the comments on his blog, Jack states that the “Yealmpton chairs were in production prior to 1780“. If true, it means that the continuous-arm Windsor chair, rather than being the invention of some ingenious American chairmaker, is just another style imported from England, like all the rest.
(For the curious: I tried to do a bit of research on the topic myself, but frankly I’m at a loss as to where to even begin. The history of English antiques is very much a foreign topic to me. So instead I asked Jack himself – a former antiques dealer – if he knew of any primary sources supported the pre-1780 origin of the style. He said that his reference books were packed away at the moment, but that he intends to follow up on the topic himself. So keep an eye on his blog if you’re interested in a firmer conclusion to this saga.)
Even if further evidence demonstrates that the style did originate in the Old Country, that doesn’t mean that American chairmakers should feel any less pride in our chairmaking heritage. After all, unlike the rather unsophisticated, stump-legged chairs from the southern coast of England, the New York continuous-arm is an enduring icon: a refined symbol of good taste, comfort, and durability.
My wife and I have this conversation nearly every time I finish a furniture piece. I ask if there’s anything she wants me to build before I start my next project. Secretly, I’m always hoping that there’s nothing in particular that she wants so that I can pursue whatever suits my fancy. But there’s pretty much always something in particular that she wants. My obligation, so as not to seem neglectful, is to first build this particular thing prior to moving on to other projects that are tugging at my spirit. It is a rare and fortuitous event, indeed, when what I am asked to build is precisely what I would like to build, but such is the case with my latest project.
A high chair. A Windsor high chair, to be exact. A continuous-arm Windsor high chair, to be pedantic. (Those last two specifications are of my own preference. I was only asked to build a high chair.)
You can buy Windsor chair plans for lots of different types of chairs: fan-backs, comb-backs, loop-backs, balloon-backs, sack-backs, and continuous-arms. With or without rockers. But where do you get a plan for a high chair? Heck if I know.
Although I reject published plans for the majority of my furniture, I am not quite at the point where I would feel comfortable designing a Windsor chair. They are complicated little sons-of-guns. I implored chairmaker Elia Bizzarri for help. His suggestion?
“You can take Curtis Buchanan’s Continuous Arm or Comb Back plans and reduce the seat and back to 2/3 scale. The legs are 22″ long and the diameters are the same as the full size chair. Rear leg angles (into the seat) are 22 degrees and the sight line runs through a point on the CL 3.5″ from the front of the seat. Front legs are at 15 degrees, sighted at a point on the CL 5″ back from the front of the seat.”
That may sound like gibberish to someone unfamiliar with the language of Windsor chairs, but it was all I needed. The good news is that I already had Curtis Buchanan’s continuous-arm plans as a Christmas present from my in-laws. Scaling them down was as simple as setting up the copier at work to 67%, and off I went.
Since I had no wood at the moment that would be suitable for the arm rail, it made sense to start with the undercarriage. First up was the legs. At 22″ long, these required a bit of scaling, as a normal chair leg is 18″ long. I found that the best appearance was gained by extending the balusters (the vase-shaped part in the middle) and the foot, and leaving the rest of the details (coves, beads, and birds-beaks) unchanged.
With those done, I turned my sights to the seat. The full-size seat is 18.5″ wide, but at 2/3 scale, I only needed a board a little over 12″ wide. Easy enough to find. I left the thickness at 2″, since I reasoned that the additional thickness will give greater purchase for the leg-to-seat joinery.
The carving process is identical to the last Windsor chair: First, flatten and thickness the board, then lay out and drill all of the holes for the legs and spindles, then carve and shape the seat.
Flatten and thickness with a hand plane.
Mark out the holes and drill them with the aid of a mirror and bevel gauge.
Carve the gutter.
Get the hollow started with an adze.
Finish it off with the inshave, travisher, drawknife, and spokeshave.
Shape the underside with a drawknife and whatever else fits the bill.
I labored on my first Windsor chair seat for a few days, trying to understand the shape and making sure everything was just right. This one was done in a matter of hours. It’s amazing how much more quickly the work can proceed once you have the end goal firmly planted in your mind. I was not as timid to waste away the unnecessary material, because it was now immediately obvious to me which material was unnecessary.
Finally, I reamed the leg holes and made a few wedges, and the undercarriage was ready for assembly.
Wedges for the legs. Split a chunk of hard maple and shave them with a wide chisel.
Saw the legs flush where they poke through the seat.
The assembled legs and seat.
With that done, it was time to start on the spindles and the arm rail. Since no suitable wood grows on my little island on the Florida coast, that will require a road trip. Luckily, my dad lives in Colbert, Georgia, in the midst of the oak-hickory region. Even more luckily, he owns a small sawmilling operation, and white oak just happens to be his specialty…
“A craftsman, from the bottom of his or her heart, is to serve society. Every profession has social obligations and responsibilities. The craftsman’s social responsibility is to fulfill society’s demands as best they know how. Unlike craft, society does not ask the artist for what it needs. The artist’s social responsibility and obligation is to find a valid concept and execute it, then share it with society…whether society likes it or not.” -Toshio Odate
A couple weeks ago, I posted about the “Quick and Dirty” table that I built for my son. As a child’s play table, I didn’t fuss too much over the finish. I did get Elam’s input on the color. He said he wanted blue, so I gave it two coats of blue milk paint and slapped on a coat of shellac and called it good. The quality of the finish matches the aesthetic of the rest of the table. In other words, it’s functional and not necessarily bad-looking…but don’t look too close.
Now, time for an admission. The need for this ‘quick and dirty’ table came about due to some piss-poor planning on my part. You see, originally, it was the tavern table that was supposed to serve as Elam’s play table. When my wife first asked me to build a table for him, the wheels in my head started spinning, and before long, I recalled the attractive little Charleston tavern table that had been featured in Popular Woodworking and in “Furniture in the Southern Style“. I had always wanted to build that table, and here was my wife asking me to build at table! Perfect!
Now, most children’s tables can tolerate a fairly broad range of heights, sizes, and designs. After all, kids grow, so you can either build a table that’s too big for them now or one that will be too small for them in a couple of years. What they really need is a chair to match the table, so the kids can work and sit at a comfortable height.
However, our Elam is a special kid. He was born with spina bifida and uses a wheelchair. Thus, with the height of his chair pre-determined, I had to built his table at a height that would match. I measured and determined that 23.5″ would be the ideal height for his table. The original table was 27″ high. Hmmm…dropping the height by 3.5″ seems like it would ruin the aesthetic. I decided to compromise and build the table 25″ high instead. Surely that extra inch and a half would be okay, right? And he would eventually grow into it anyway, right? That was mistake No. 1.
Next, it was obvious that the lower stretchers that are found around the lower perimeter of nearly all tavern tables would be in the way of his wheelchair. No worries, though – I could just nix the front and back stretchers and use a single stretcher in the middle instead. And there’s mistake No. 2.
My wife packed up the kids and headed to off to visit her parents for a weekend. I was tasked with building the table for Elam. And I worked a 30-hour weekend building that table. With hardly any sleep, I kept single-mindedly to the task at hand, and was just pegging the top in place when my wife rolled into the driveway on Sunday afternoon. I was so excited to roll Elam up to his new play table so he could try it out.
My excitement quickly soured as I realized that 1) the addition of 1.5” of height above my “ideal” estimate placed the tabletop in a position where he could barely see anything on the tabletop, and 2) I neglected to ever measure the distance between the front wheels of his wheelchair, and as a result the distance between the table’s front legs was 1/4″ too narrow for the wheelchair to squeeze in between. My own disappointment was only exceeded by that of my wife. It was not a good way to start off a week for anyone involved.
I certainly didn’t slave away for 30 hours over two days to build a non-functional piece. I thought I was doing heartfelt work that would genuinely be appreciated by my son and my wife. But I got caught up in my own aesthetic preferences and lost sight of the original purpose. It was a painful lesson. And one that I quickly made right, two days later, in a two-hour flurry of workshop activity.
The new table may not measure up to the tavern table in style, but it well exceeds in the category that counts: function. Now, I know there is a big arts vs. crafts debate that has been raging for centuries and addressed ad nauseum by folks far more experienced and eloquent than I. I don’t intend to weigh in on this debate, because for me, there is no confusion. I am not an artist; I am a craftsman. If Toshio Odate is to be believed, my primary concern in this specific role is “to fulfill society’s demands” as best as I know how. And since I the lion’s share of my work remains in my own home, the “society” to whom Toshio refers would be my very own family.
I would do well to remember my role. I know of one little guy who certainly appreciates it when it when I do.
The tavern table was a fun build, and quick, too. Relatively speaking. I compare everything now to the Windsor chair build that stretched on for three months. It’s amazing how simple everything becomes when all of the angles are at 90°. And how convoluted things become curves and angles that aren’t right come into play. I started the table on a Friday evening, and it was fully assembled by that Sunday afternoon.
I have a few pictures, but must apologize for the quality. The lighting in my house is atrocious, and outdoors isn’t any better. Our yard is a scrubby wasteland of sand and weeds a few blocks from the beach.
I was surprised how much visual interest this simple molding on the bottom of the aprons adds to the table. I’ve never used a detail like this before, but I’ve noticed that some sort of molding is present on the aprons of nearly every joint stool and tavern table that I’ve seen. Definitely worth the small effort to get this effect.
The legs were a blast to turn. The shape is very, close to the original, but I didn’t hold myself too closely to the details. I felt that they could use improvement, so I improved them. I’m very happy with the way these turned out. Plus, it was extra practice for my next Windsor chair! I’m still having trouble with the skew chisel on those beads – I find that to be the hardest part of baluster turnings.
Another tweak to the original design: I reduced the number of lower stretchers from four to three, and moved the long stretcher to the center. I did this so that the table can be used as a children’s dining table when we have a lot of company. My son is in a wheelchair and needs to be able to roll up close to the table; outer stretchers would prevent that.
I also used chamfers and lambs’ tongues instead of the simple roundover on the original. No reason, other than I like the way they look.
I do love drawer-building. Especially small ones like this. It becomes harder to make a smooth-running drawer as the size increases. This drawer fits nicely with maybe 1/32″ gap on the sides and 1/16″ on the top. It slides sweetly.
And of course dovetails are ever fun to cut.
I even found time to add a bit of bling to the drawer bottom. I have wanted to try some Peter Follansbee-style carving for years, and I finally made it happen. I didn’t want my first carving to be front-and-center on a piece of furniture, so a drawer bottom seemed appropriate. The carving is a bit of an anachronism – 17th-century English carving in an 18th century Charleston table – but it doesn’t bother me. Avert thine eyes if thou art a pedant.
The table still needs a finish. It will be painted, like the original. Unlike the original, I will not be using oil paint with toxic heavy metal-laden pigments. Milk paint will suffice. I’m thinking blue over yellow, with shellac topcoat.
If you follow this blog, then chances are good that you follow Chris Schwarz’s remarkably prolific blog as well. If not, then perhaps this post deserves a bit of background. For the last couple of years, Chris has been deep down in the rabbit hole of “staked” furniture. I’ve followed it with curious interest, but along with his foray into campaign furniture, it’s not exactly my style, so I haven’t really been tempted to play along. “Staked” is a term used in early estate inventories used to describe furniture that consists of a wide slab top, with simple legs mortised through the top. The joints can rely on a cylindrical or cone-shaped tenon, but either way, it’s basically the same joint that affixes the legs to the seat on a Windsor chair.
The joint was prolific in Europe for hundreds of years, being used in everything from stools and benches to tables and chairs. As joinery became more complex and tastes in furniture more discerning, its use fell out of favor for all but cruder furniture and a few other specialized contexts.
Windsor chairs avoid the crude look engendered by staked joinery by virtue of elegant turned legs and a comfortably shaped seat. A flat-topped table has more trouble shaking of the humble look of the joinery. Yet the technique does have one distinct advantage: it’s fast.
My wife wanted me to build a play table for my two-year-old son. She wanted it soon. “I don’t care if you nail it together, I just want it done.” She had been asking for weeks, so her impatience was justified. However, I tend to put things off until I can find the time to build a true object of beauty. She quickly objected that children’s play table needn’t be a thing of beauty. Counterproductive, really. A play table is something that should be used and abused without fear of rebuke. Paint, crayons, markers, Play-Doh, glitter-glue. These humble playthings are instruments of doom to a fine piece of furniture.
A staked table was just the answer. So, two nights ago, I walked into my shop at 8:30 PM after the rest of my household was asleep. At 10:45 PM I walked out with a finished table in my arms – hand tools only, except the lathe. The tavern table that has been featured in my last two posts required 40 hours of shop time to build (you’ll get to see the finished object soon, I promise). The play table is about the same size, and I knocked this sucker out in 2 hours, 15 minutes. Now I know why this style hung around for a few hundred (thousand?) years. Economy of labor is a beautiful thing.
Despite not measuring a damn thing on this table (except the height), the angle of the legs turned out pretty close. I really don’t think I could have done better if I was measuring instead of eyeballing.
And the best part about a quick and dirty table? I was happy to let my 4-year-old daughter help me with the paint job. And she was excited to help.
How long will this table last? 10 years? 25? 100? I have no idea, but I have no doubt that it will serve its purpose for as long as we need it.
That’s a wrap. The chair is in the books. Last weekend, I burnished the last coat of black milk paint and oiled the chair with walnut oil. I may yet go over it with a few more coats of oil, because the finish is a bit duller than I’d like, but that won’t change the appearance much except to add a bit more shine. Last night, I got out an old white table cloth and my wife’s SLR and tried to take a few decent pictures. Hopefully they prove that I am at least as good at building chairs as I am lousy at taking pictures of them. Thanks to everyone who followed along and offered encouragement and kind words. And thanks especially to Peter Galbert (author of Chairmaker’s Notebook and the Chairnotes blog) and to Curtis Buchanan (creator of tthis awesome YouTube series on Windsor Chairmaking). I defintely couldn’t have done this without their help.
I’ve never tackled a project that required so much patience, research, and preparation before. I am prone to dive headfirst into a project, even a big one, with the assumption that I can just figure things out at I go along. Usually it works out fine. Occasionally it ends in frustration. There have been a few points over the last few years where I’ve walked out of the shop with a half-finished project and refused to go back in for weeks or months. Or at the very least, I’ve put aside a project and continued on with other things, sometimes for years, until my tools or skills caught up to my original vision. I can’t think of many things that breed negative emotion quite like the sight of a half-finished project mocking me every time I walk into what is supposed to be my happy place, my temple, my cozy respite from the rest of the world. I know that feeling too well, and I’m glad that, in this instance, I knew better than to tackle this project until I knew I was prepared. There is nothing quite like the enthusiasm of youth, but I’m hoping this project marks the wisdom of age beginning to take hold.
I’ll leave you with a few picture of my new favorite thing:
This video is a few years old, but since it’s an hour long, I had never taken the time to watch it. I finally rectified that situation one evening this week. It’s a great introduction to Windsor chairs by one of the modern masters of the craft, Peter Galbert. If you love Windsor chairs (or if you’re wondering why I do) it’s well worth the watch.
Well, that title sounded a bit more salacious that I intended. No really, I’m writing about wood properties here, not the unfortunate results of skinny-dipping in a cold pool.
In this, our second edition of Woody Wednesday, we will discuss the one wood property that causes more ruined projects and gnashing of teeth than practically any other – its propensity to expand and contract with changes in moisture content.
Wood is hygroscopic and anistropic. Hygroscopic means that it has an affinity for water – very helpful for a living tree, which must conduct thousands of gallons of water tens to hundreds of feet above ground through the pores of its wood to reach its leaves. Let’s pause for a moment to consider what a marvel this is. This video will help:
Those water-conducting pores are what makes wood anistropic – meaning that its properties are different depending upon direction. You can think of wood like a bundle of straws. The properties at the top of the straw bundle are very different from the properties along its sides. The opposite of anistropic is isotropic – materials that have the same properties in all directions. Examples of isotropic materials are metal and glass. On a microscopic level, you could correlate them to a jar of sand, rather than a bundle of straws.
Wood vs. Steel
Wood is like a bundle of straws – different in every direction.
Steel is like a jar of sand – the same properties in every direction.
It is this combination of hygroscopic and anistropic properties that causes wood to shrink and swell with seasonal variations in moisture content. When we saw or split wood from a log, it contains water. Lots of water. Some of this water is what we call “free” water. This is the water that was moving freely up through the pores, from the roots to the leaves. The wood also contains “bound” water – water that is chemically bonded with the cellulose and lignin that make up the cell walls.
When the wood begins to dry, the free water tends to exit the wood rather quickly. Since it isn’t chemically bound, it is free to evaporate. The point at which no more free water remains in the wood is called the fiber saturation point. Only bound water remains. This occurs at 25-30% moisture content.
What exactly is moisture content, by the way? You’ve probably heard it mentioned, have you ever wondered what it means? It’s pretty simple: moisture content, or M.C., is simply the weight of the water divided by the weight of the woody, fibrous material, expressed as a percentage. So a 100 g sample of wood at 26% M.C. contains 20.63 g of water and 79.37 g of actual wood (20.63/79.37 * 100 = 26%).
As the free water dries, the wood changes very little in size and shape. After the bound water begins to dry, however, funny things start to happen. When water that was previously bound to the cell walls evaporates, the cell walls contract. This wouldn’t be problematic if the wood shrank evenly, but wood is anistropic, so the shrinkage occurs differently depending on what plane we’re looking at.
When scientists talk about wood, we discuss three different planes: transverse, tangential, and radial. As woodworkers, we tend to refer to these planes as end grain, quartersawn grain, and flatsawn grain. There’s also a term for a plane that is in between quartersawn and flatsawn, which we call riftsawn. I’m not an artist, but here’s a drawing to wrap your mind around it:
Wood reacts very differently along these three planes. It shrinks very little or not at all along the grain. It shrinks 2-6% in the radial plane (from pith to bark), and about twice as much (5-10%) in the tangential plane (along the growth rings) from the fiber saturation point to air-dry. This calls for more custom artwork:
This differential shrinkage has a profound impact on the stability of the wood as it dries. Quartersawn wood tends to be the most stable, but it will shrink in thickness more so than flatsawn wood. Flatsawn lumber has a definite propensity to “cup” as it dries due to the differential shrinkage between the tangential surface in the middle of the board and the riftsawn grain on the edges. Something that is turned round from green wood will end up egg-shaped as it dries. Again, a picture should help to visualize these effects:
Wood is considered “air-dry” when the moisture content of the wood reaches equilibrium with the relative humidity of the air. Scientist call this the equilibrium moisture content (EMC). It can be as low as 5-6% if you live in the desert, or as high as 15-16% in a rainforest. A more common range for air-dried wood in temperate climates is 10-12%.
Now, wouldn’t it just be dandy if we could dry our wood down to the equilibrium moisture content, and then have a stable, predictable material that we could glue and screw to our hearts’ desire, without any consideration for dimensional changes over time? That would make everything so easy!
There’s just one problem. Wood will always, always, reach equilibrium with the air surrounding it. So unless you live in a temperature-and-humidity-controlled laboratory, you can expect weather patterns, seasonal changes, and modern heating and air-conditioning to cause the moisture content of your wood to vary by 3-4% in normal use. This might not sound like much, but if you don’t incorporate allowances for wood movement in the design of your furniture, the results can be catastrophic wood failure.
Putting It Into Practice
Consider the sassafras table that I built a few weeks ago. The top of the table is 48″ wide. Sassafras is a pretty typical domestic hardwood in regards to dimensional stability. It changes by about .003″ (three thousandths) per inch of width for each percent of change in moisture content. Three thousandths sounds like we’re picking nits, but the numbers multiply rapidly. If we assume that the MC starts out as 12% and drops to a minimum of 8% in the dead of winter with the heater running at full blast, that’s a 4% change in MC. Multiply .003 x 4 (% MC change) x 48′ (width of the panel in inches) and we get 0.576″ in shrinkage along the width of the table. That’s over a half-inch!
So, since the wood does not shrink along it’s length, if I had screwed down the battens without making allowances for wood movement, it’s obvious that the result would be, at best, a severely bent tabletop, or more likely an ugly split right down the middle. Wood will swell as it absorbs moisture and shrink as it releases it. It is as certain as the sun rising in the east and time slowing down as you approach the speed of light.
Since I am fully aware that my tabletop will shrink, I was able to design the battens with this in mind. I drilled elongated holes into the battens and screwed the top on using washers, which will allow the top to shrink and swell with the seasons, all the while sliding as it wishes along the battens without bending or splitting.
This is but one of many examples of designing furniture to allow for seasonal wood movement. The most famous example is the ubiquitous frame-and-panel door. The narrow members of the door experience very little movement, but they house a wide panel in a groove that is free to shrink and swell as need be without affecting the dimensions of the door. If doors were designed from solid wood, they wood stick shut as they swelled in the summer or leave ugly gaps as they shrunk in the winter.
Okay, so now you have a basic understanding of why it’s necessary to design your furniture with wood movement in mind. It’s beyond the scope of this (already long) article to discuss any more specific techniques for addressing wood movement, but a basic understanding of wood movement and a little common sense can go a long way to avoiding furniture failures.
I will tell you that I typically take a very unscientific approach to addressing wood movement myself. I know that my wood will shrink when I move my furniture from my un-heated, un-cooled workshop to inside my house, so I plan for it. I typically figure that the wood that comes out of my shop will be around 11-12% MC, but I never measure it. I have probably used wood as high as 14% MC, but since my furniture is designed with wood movement in mind, this is never problematic in practice.
The woodwork inside my house is generally around 9-10% MC. Maybe a percent drier in the midst of winter, or a bit wetter when the windows are open during the spring. Figuring on a maximum change of 5-6% is generally pretty safe. But again, I don’t bring any numbers into my figuring. Wide panels get more allowance than narrow members. Experience is my guide. If you are uncomfortable with this seat-of-the-pants design, then Popular Woodworking has a great online resource for calculating wood movement. Give it a shot.
Also understand that the numbers for EMC in my neck of the woods may be vastly different in your part of the world. Check out this page for typical EMC in different cities in the United States.
Finally, if discussions of equilibrium moisture content, hygroscopicity, and transverse planes has really whet your appetite, the Wikipedia page on Wood Drying is actually quite excellent.
It’s one thing to design your furniture such that we avoid problems with wood movement. But what if we could design furniture that actually takes advantage of wood movement? Wouldn’t that be something?
In fact, woodworkers have been doing exactly that – for centuries. But that’s a topic for another day…
Saturday was my birthday. Which means I need to update my “About” page, since I’m no longer “nearly” 32 years old. When my wife asked what I wanted to do for my birthday, I had an easy answer. I wanted to spend the day smoking a pork butt.
I don’t know if there’s a better way to spend a Saturday. Get up early (but not too early), grab a bucket-full of shavings from the workshop, and light up a fire.
Slather a pork butt in salt and spice and sugar, and throw it on the smoker (my personal favorite cut is a picnic shoulder, but a Boston butt works too).
Now, kick back for the next 10 hours, enjoy a few ice-cold brews, and every hour or so shovel another heap of coals into the smoker and add another slab of oak to the glowing bed of embers.
Utter bliss. There’s plenty of time between tending to the meat and the fire to get a few things done around the house, but no time to leave. It’s self-imposed subjugation at its finest.
There were two things I wanted to get done: finish the shavehorse, and get started on the Windsor chair. I had been monkeying around with some wood property data and wanted to test the suitability of live oak for chair legs. Unfortunately, I didn’t have a lot to choose from, but I disappeared into the woods for a while and came back with this homely little specimen.
It’s ugly, but it’s the best I could muster. I cut two sort-of-straight 24″ sections out of it.
And set about riving it into useable billets. The devilish wood required two hatchets, two steel wedges, two dogwood gluts, and an obscene amount of pounding before it even thought about splitting.This little tree had a dirty secret, a crooked past that it was trying to hide under a straight-laced veneer. I caught the first whiff of the evidence when I saw the off-center pith, but the truth was laid bare for all to see when it finally opened up.Devious little scoundrel. Oh well, once the first split is made, the hardest part is over. There wasn’t much left to do but continue splitting. Once I had the pieces riven down into quarters, I knocked off the crooked juvenile wood with a hatchet.
The last split was the easiest. With the crookedest wood removed, I was able to split the billets into eighths pretty easily, and soon I had a whole stack of the grisly little things.
Nothing to do now but to pop them on the lathe and see how they turn. Turning these things round was a pretty nasty surprise as well. The long fibers left from the riving hang on with the tenacity of a tick, and when you turn the lathe on, they jump out and swat your knuckles like a bullwhip. It reminded me a lot of turning hickory.
After a few minutes, I was able to beat the oak into submission once more, and I had a nice, consistent cylinder. A couple hours later, I had processed all of the rough blanks into 1 5/8″ cylinders.
Only one problem: I misread the plans. For the shapely baluster legs that I had envisioned, I needed a stack of 2″ blanks, not 1 5/8″.
Damn. Well, there is one bright side: My wife actually prefers the simpler style of the bamboo legs. So, since she doesn’t actually read what I write, I get to pretend that I changed the design to suit her tastes. Score! Anyway, I hope for this to be the first of many Windsors, so I’ll just have to do the baluster legs next time.
Honestly, I think it became apparent to me that live oak (at least, green live oak) is more suited to the reserved curves of the bamboo turnings anyway. I found it to be hard and splintery and really not very fun to turn. I also got a gunky buildup on my tools that I haven’t noticed as much when turning other green woods, which required re-sharpening even if my tools weren’t actually dull. I fear that live oak might chip out around the crisp details of the baluster legs, or that the gunky buildup on my tools would make those details more difficult to achieve. I suspect it would work a lot better if I roughed out the blanks and then waited for them to dry before attempting any baluster turnings with live oak.
I will say that I have no complaints about the results. I was able to achieve a very nice polish straight from the tools. This is important to me, because I consider avoiding wood dust (and the lung cancer that goes with it) high on my list of priorities. I would have no patience for this wood if I had to sand it as well.
A few hours before this picture was taken, these legs were part of a living tree in the woods behind my house. Green woodworking never ceases to enthrall me – the connection between the raw material and the finished products is visceral and unforgettable. Three stretchers to go, and all of the parts for the undercarriage will complete. All they require is time to dry. The Windsor chair is underway!