Words and photos: Kerry Pierce
This chair is a reproduction of a side chair offered for sale to the ‘World’ by the chair workshops of the Shaker community at New Lebanon. Although Shakers in all communities sold a wide variety of goods to the outside world, the New Lebanon chairmaking workshops under the direction of Brother Robert Wagan have achieved an almost mythical stature among connoisseurs of Shaker furniture. In those workshops, Wagan developed methods to mass produce a wide variety of Shaker chair forms while remaining faithful to Shaker design principles of minimalism and elegance.
In the sequence of New Lebanon chair sizes, this is a No.6, ranking it as the second largest side chair in the New Lebanon catalogue, making it about the right size for average 21st century Americans (and Australians), who are physically larger than were their 19th century counterparts.
The Shakers built their chairs from hard (rock) maple, which is dense and tough, ideal for a chair composed of slender attenuated parts. As a result, I too work primarily in hard maple, but I have made chairs from American ash, oak, walnut, and cherry—and all these woods have resulted in perfectly usable chairs—although I no longer sell chairs made from cherry because I know that under a heavy load, it is possible for a cherry rung to fail.
I’m not a wood technologist, and my experience with Australian blackwood is limited to the construction of this one chair using material that AWR sent me, but my perception of the wood is that—like American cherry—it may lack the strength to be an ideal chairmaking wood*. It is noticeably less dense than American hard maple, and I was able to break a test rung over the edge of my bench, something that wouldn’t have been possible with maple. Nevertheless, the chair is now in my home and being used daily, and that is one of the great things about Shaker chair design: despite the lightness and apparent fragility of most Shaker chairs, they achieve enormous strength through the interconnection of many slender parts.
Turning the posts
The back posts of Shaker chairs require lathes with an unusually long distance between centres, often over 1000mm. Twenty years ago, when I began making chairs, I didn’t have the money to buy a good big lathe, so I bought a cheap small lathe and modified it to accept long stock.
The modification consisted of welding a second mounting foot to the end of the tubular lathe bed that would ordinarily have fitted into the headstock. Although my technique for lengthening my lathe bed might not work for you, I’ve never yet seen a lathe that couldn’t be lengthened—although some take more head scratching than others.
Even experienced turners can struggle to turn the long, thin parts required by Shaker chairmaking. The front rungs and back posts in particular can be challenging to control because what you find is that if you push your tool against a long, thin piece of work that’s spinning in your lathe, the work will flex away from the tool, resulting in chatter as the work vibrates against the tool. To reduce the tendency of the work to flex, I have three suggestions:
1. Choose a mid-range lathe speed. I use 1350rpm. If you turn with excessive speed, there is a danger of the work coming apart in the lathe or breaking loose from its centres, and a 1000mm post blank cartwheeling from your lathe can wreak havoc on you, your shop, and your peace of mind. Conversely, if the speed is too slow, my perception is that the work gives too easily under the pressure of the lathe tool. This is something I’m not enough of a scientist to explain, but my perception is informed by many years of experience.
2. Don’t push the tool into the work. Lay the bevel on the work, and lift the handle until the edge engages the work. There will always be some pressure of tool against work, but I think it’s helpful to avoid thinking of the work/tool interface as a point of resistance requiring force.
3. Use your off hand as a steady rest. I wrap a few turns of masking tape around my right hand (I’m left handed), and that protects it from friction burns when I use it to lightly support the back side of the spinning work.
I recommend that inexperienced chairmakers begin by turning the short back and side rungs and then move onto the
posts, saving the tricky back posts for last.
Cut X’s on the ends of the blanks to locate centres. I do this on my bandsaw because it’s so much quicker than doing it with a handsaw. Then tap an awl into the endgrain to locate the centre.
Mortise and tenons
A post-and-rung chair is held together by fitting round rung tenons into round mortises, that are cut into the turned posts. I use a 5/8” (16mm) forstner bit which produces very consistent and accurate mortises. The tenons require a bit more skill to fashion accurately.
I begin with a 1/2” fingernail gouge and create a hollow in the tenon with a least diameter of 5/8”.
I then switch to a 1” butt chisel laid bevel-side-down on the rest and scrape the tenon until the diameter along its entire length equals its least diameter. I then cut a 1/16” (1.6mm) taper on the end of the tenon to enable it to better slide into its mortise.
Notice that the rungs taper from a greatest diameter of about 23mm to a least diameter of about 17mm at the shoulder next to each tenon.
The back posts also taper, from a diameter of about 36mm just above the seat rungs to a diameter of about 23mm just below the cove under the acorn finial. The cove, which I form with a couple of passes of a 3/8’ fingernail gouge, measures about 10mm at its smallest diameter. After I’ve turned a run of chair parts, I re-centre each and lathe sand them through a succession of grits: 100, 150, 220.
Marking the posts
My lathe has an indexing head which simplifies the process of accurately marking rung mortises, but it is possible to produce usable markings without the use of a lathe with an indexing head. I’ll describe both methods.
An indexing head is a disc centred on the lathe’s axis of rotation which has holes bored at regular intervals near its circumference. The indexing head on my lathe has 36 equally spaced holes, which means I can divide any object turned on my lathe into 36 equal segments, each of which is 10° from the next. My lathe also has a spring-loaded pin on the headstock which allows me to lock the lathe’s indexing head (and its rotation) at each of those 36 stops.
The centreline of the front rungs on this particular side chair is 82.5° from the centreline of the side rungs. To mark the front posts, I select a location for the centre of the front rung mortises and lock the lathe’s rotation with the spring-loaded pin so that the centreline is facing me.
I then slide my marking jig along my lathe bed so that its pencil marks a line along the length of the front post. I then click off eight stops (80°) on my indexing head, lock the indexing head, and with my marking jig, make a second line marking the centre of the side-rung mortises. These line placements around the post’s circumference are not exactly 82.5° degrees apart, but they’re close enough. The side rung mortise jig (SRMJ)** will create the exact placements. At this stage all you need is an approximation.
I then lay my front post story stick along the post and mark rung centres along each of the two lines I made using my marking jig, one set of marks locating front rung mortises, the other marking side rung mortises.
I use the same procedure to mark the back posts with one exception—the centreline of the side rungs is 97° from the centreline of the back rungs, which means counting off ten stops on the indexing head. I then mark rung mortise locations (and slat mortise locations) along the two lines on the back posts. If you don’t have an indexing head on your lathe, you can achieve a very similar result on your bench top.
Rip a wide, flat carpenters pencil in half along its length so that the lead (graphite) is exposed. Snug up a pair of front posts on your bench side to side with their ends aligned. Then the leaded half of the carpenter’s pencil along the snugged up posts, with its length perpendicular to the lengths of the posts. In this manner, you’ll create a line on each post that is parallel to the post’s centreline. Then rotate the posts so that these centrelines are facing one another, and once again snug up the posts and draw lines along their lengths using the ripped carpenters pencil. These second lines will be 90° from the first pair of lines. Do the same with the back posts.
In each case, you’ll have lines about 10° from ideal placements, 10° too far on the front posts and 10° not far enough on the back posts. Fortunately, those errors don’t matter because the SRMJ will create accurate placements on the circumferences of the posts. All you need at this point are approximations along which you can mark the rung mortises.
The front and back rung mortises are drilled next using a front rung mortise jig. This jig should be set up so that its fence is a distance from the lead point on your forstner bit that is half the diameter of the post. So if your posts are the ideal diameter of 36mm, you will set the fence 18mm from the lead point. Also, you should set the depth stop on your drill press so that you’re drilling mortises 15/16” (24mm) deep. This will accept 7/8” (22mm) long tenons and allow a bit of extra length as a glue reservoir.
The front ladder can be assembled at this time. Be sure to check it for square before setting it aside to dry. The back posts can then be steamed preparatory to bending.
My steamer is a deep-fat frier my wife bought 20 years ago at a garage sale. I cut a round hole in the frier’s metal lid to accept one end of a 1500mm length of 100mm diameter PVC pipe. I screwed a wire mesh across the bottom of the PVC pipe to hold steamed parts above the water. I also bought a cap for the top to hold in the steam—although I found I get the best flow through the PVC by drilling a half dozen holes through the cap. Without those holes, the steam tended to escape around the lid of the deep-fat frier, rather than traveling up through the PVC.
The design of your steamer is limited only by your imagination. All that’s required is a source of heat to boil water and an enclosure to hold the wood parts while the steam passes by them.
I start by bending the 1/4” (6mm) thick slats. These should be sawn to shape on the bandsaw and the top edges rounded with a spokeshave or rasp before they are placed in the steamer. Because they’re so thin, they need only 30 minutes in the steamer. I then pull them out, place them in my bending jig**, and squeeze them into shape in bending forms held between the jaws of my bench vice. I just leave them in the vice until their bends have set, but you can lock the two parts of the jig together with clamps or U-bolts and remove them from the vice.
I leave the back posts in the steamer for 90 minutes. I then remove them and quickly place them in the bending jig with the back rung mortises facing up. I then slip a pair of wood collars over the slender end of each post and a hose clamp over the two collars. Next, I use an electric drill with a bit extender to tighten the hose clamp. This allows me to bend these large back posts with relative ease. The bent parts should then be set aside for about a week so that the bends can set.
Cutting slat mortises
I chop slat mortises by hand, using a mortise chisel that is ground to a bit less than the 1/4” (6mm) thickness of the slats. I begin by clamping the steam-bent post to my bench with the slat mortise up.
Before you cut any slat mortises, study the photos carefully. There are two important considerations. First, the front (relative to the finished chair) of the slat mortise is placed on the centreline of the back rung mortises. This is the centreline you made when you were marking the rung mortises. Second, the slat mortises have to enter the post at the same angle as the back rungs. To ensure this I place a back rung upright in the bottom back rung mortise as a reference when I’m chopping slat mortises.
With a marking knife, I define the front and back of each slat mortise. I then begin chopping them out with my mortise chisel making frequent checks of my angle by placing a slat in the half finished mortise and sighting from the bottom of the post.
Notice that the drawing indicates a different tenon length for different slats. The tenon length simply indicates the amount of slat that penetrates the post. There is no shoulder.
The photo above is the most important in the article because it shows the alignment of slats and back rungs. The ‘reference’ back rung I have in the bottom mortise gives me something to sight against when I’m checking to see that the slat mortises are entering the posts at the correct angle. Please study this photo before chopping your slat mortises.
Assembling the ladderback
Once the slat mortises have been chopped, the back ladder can be assembled. Begin by clamping one post—mortise-side up—to your bench top. Apply glue to the tenons of the slats and back rungs and install them in their mortises on the clamped post.
Then start the tenons into their mortises on the other post. This will be impossible. At least that’s what you’ll think at first. There are simply too many parts to get started all at once, but if you take your time, working from one end of the post to the other, starting each tenon as you go, eventually you will get them started. Then remove the assembly from your bench and—standing behind the partially assembled back ladder, lay a clamp across the front of the ladder.
Then—starting at the bottom of the ladder—begin drawing the two posts together a bit at a time working your way up and down the ladder with the clamp. Often, the slats will get stuck in their mortises. I coax them into place by squeezing together the middle of the slat and the bar on the clamp. This causes the ends of the slat to pop further into their mortises.
Carefully wash away any glue squeeze-out. I find a toothbrush and a bit of water is ideal for getting glue out of the intersections of rungs and post. Give the ladder a check for square by standing the ladder and a framing square together on your bench. The posts will spread just a bit as they rise from the bench. What you want is an equal amount of spread on each side. Then set the ladder aside to dry.
Assembling the chair
Another jig will simplify the process of drilling accurate side rung mortises. It is designed so that in one position it will drill the mortises on the front ladder: mortises with centrelines 82.5° from the centrelines of the mortises for the front rungs. Then, by turning the jig around 180° on your drill press table, you can drill the supplementary angles for the mortises on the back ladder: mortises with centrelines 97.5° from the centre-lines of the mortises for the back rungs.
The jig should be set so that its fence—in both the front ladder and the back ladder positions—is a distance from the lead point of the forstner bit that is half the diameter of the post. And here too, the drill press depth stop should be set to drill a 15/16” (24mm) deep mortise.
I would also recommend that you turn a bit of scrap to the right diameter and—holding it against the fence—cut a couple of mortises in that scrap to make sure you have the jig set up the way you want it.
You’ll notice that—even when the jig is set up correctly—the lead point on the forstner bit may not hit your mark’s dead centre. That’s not necessarily because you have the jig set up incorrectly—although it may be. Instead, the error is most likely to be a marking error. It’s very difficult to get pencil lines that are dead on the right location around the outside diameter of the post. A properly set up jig, however, will find the exact locations.
When the mortises have been drilled in both the front and back ladders, you’re ready to assemble the chair. Lay the back ladder front-side-up on your bench. Apply glue to all the side rung tenons. Then start the tenons in the mortises in the back ladder. At this point, lay the front ladder on top of the protruding side rungs and start the tenons into their mortises. When all the tenons have been started, stand the chair upright on your bench. Then, with a pipe or bar clamp, press the tenons into their mortises.
At this point, you need to check the stance of the chair on a reliably flat surface. I use my ground steel tablesaw top for this purpose. If the four feet of your chair don’t all meet the flat surface at the same time, rack the chair until they do.
Then step back and sight the chair from the front. Sight the alignment of each front post against the back post behind it. They won’t align perfectly because the back ladder splays a bit as it rises from the surface. What you want to see is the same amount of splay on the right and left sides of the chair. If you see error, try to correct it by racking the chair.
No chair will be absolutely dead-on perfect, so don’t expect to see that. When you get as close to perfection as you can manage, wash off the squeeze-out. Then set the chair aside to dry.
Chairmaking is a fairly complicated and specialised woodworking process, but in my experience, few things can rival the excitement you’ll feel as that first piece of functional seating furniture comes together under your hands. Enjoy.
* Alternate Australian timbers for this project are: Tas myrtle, Vic ash, jarrah, hoop pine (older wood). Please note that the author’s imperial measurements have been used for the sake of simplicity. Chisels and other tooling used by the author are sized in inches as their equivalents available in Australia are.
The process of seat weaving is described in Kerry Pierce’s book Authentic Shaker Furniture. See also Complete Guide to Chair Caning. Kerry Pierce is a furniture maker and author who lives in Ohio, USA. Get in touch via his website.
Republished from issue 52, Australian Wood Review