An Easy to Make Truss Chair

Even experienced woodworkers consider chairs hard to make well, but this truss chair design is well within the ability of novices.
By Mark Jordan
November/December 1984
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A finished truss chair.

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Most woodworkers consider a chair to be the most difficult piece of everyday furniture to make. The problem is that these usually delicate seats are subjected daily to enormous stresses (such as 200-pound people leaning back on the rear legs), and the mortise and tenon joints traditionally used to handle such loads aren't easy to construct.

Well, I've come up with an alternative design that even a novice should be able to cobble together fairly quickly, using nothing more than a hammer, a saw, some nails, and some glue. It incorporates simpler joinery — lap joints — and the structural strength of a truss framework to make a truly durable chair: My dining set has withstood five years of abuse from adults and children alike. As for aesthetics ... well, you decide. I think the design looks great, particularly when you consider the price: zero, in my case (because I used salvaged wood) or anywhere from about $2.50 per chair (for medium-quality spruce) to around $8.00 (for clear-grade hardwood) if you buy your own lumber.

Here's how to build a truss chair.

The Jig

First, you'll need to make a jig: a guide that helps you position the components accurately, and also assures that all of your chairs will be identical in design. To build one, just round up some scrap plywood and a few pieces of 1 x 2 lumber. Refer to Fig. 1, my Jig Assembly Diagram, and proceed as follows:

Use an approximately 24"-square piece of plywood — any thickness will do — for the jig's base (part Q in the diagram). Nail a 20" 1 x 2 (part R) flush with, and centered along, one edge of the base. That'll be the jig's bottom edge. Then cut a piece of 3/4" plywood to form a trapezoid (part S) measuring 9 1/4" at its top, 15 1/4" at its bottom, and 14 1/4" on each side. The sides should each form a 78° angle to the base of the jig's bottom edge (make sure that both angles are identical).

Now nail the trapezoid in place so that its bottom is flush with, and centered along, part R. Nail a 12" 1 x 2 (part T) parallel to, and 4 1/2" above, the trapezoid's base. Then affix a 9" 1 x 2 (part U) across, and flush with, the top of the trapezoid.

Finally, cut a triangle of 3/4" plywood (part V) to measure 7 1/2" at its base and 11" on each side. Then saw the top off laterally, about 1 1/4" from the tip, so that the resulting snub-nosed "triangle" can be nailed flush — upside down — with cross members T and U. Your jig is complete.

The Chair

The chair itself is made entirely of 1 x 2's; you'll need about 33 linear feet in all, cut at 90° to the lengths indicated (I've keyed the components to Fig. 2, my Chair Assembly Diagram, as well as the jig diagram).

A: Four 15 1/2" legs
B: Two 18" bottom rails
C: Two 16" top rails
D: Two 30" back rails
E: Two 12 5/8" front supports
F: Ten 15" seat and back slats
G: Two (one front, one back) 15" bottom braces

Basically, the chair consists of two side frames (which you make, one at a time, on the jig) connected by a seat, a back, and two support rails.

Begin by constructing the right side frame. Lay your jig flat on a worktable, and place a leg piece (A) against each of the trapezoid's angling sides so that the ends of each leg butt against the jig's bottom board (R). Now position the bottom rail (B) lengthwise against the bottom edge of the jig's crosspiece (T), and mark where the rail overlaps the legs (each of its ends should extend equally from the outside surface of a leg). Then set the rail aside for a moment, squeeze enough glue (Elmer's or any polyvinyl resin adhesive) onto the marked areas to cover them thoroughly, and put the bottom rail back into place. Finally, while holding one leg and the rail firmly in position with one hand, drive two 1 1/4" brads into the joint. Now do the same with the opposite leg.

Next, position, glue, and nail the top rail (C) into place, making sure that piece is pushed firmly against the jig's top cross member (U). As you can see from the illustration, the top rail's right end should extend 2" in front of the right leg. (NOTE: When you build the left side frame, position the top rail the other way around-with the left end extending 2" outward.)

Now you're ready to install the right side frame's final two members. Place the long back support piece (D) flush along the left side of the jig's triangle, positioning the outside edge of D's bottom end flush with the bottom edge of the lower rail (B). The top end of the back support piece will then extend across, and well beyond, the joint you just made at the left leg and top rail. Glue and nail the component in place, using two 2" finishing nails at the top joint and 1 1/4" brads at the bottom.

NOTE: When making the left side unit, reverse the positions of parts D and E, and place the top rail (C) so that it extends 2" out from the left leg (A) — the opposite of the placement shown in the diagram.

With that done, position a front support piece (E) along the right side of your jig's triangle, with the outside edge of the component's bottom end flush with B, and the inside edge of its top end flush with the top rail's upper edge. Now glue and nail the front support in place, again using a pair of 2" finishing nails at the top and two 1 1/4" brads at the bottom. (Remember to reverse the two supports when building the left side frame. Place the front support to the left of the triangle, and the back support to the right.)

Remove the completed side frame, put it on a solid work surface, and center-punch all the nails to draw each joint up tightly and to sink all the spikes below the wood's surface. Now set the frame aside for at least 24 hours to allow the glue to dry. Don't skip this required step! If you do, you'll loosen each glue joint when you hammer the seat and back slats in place, and your chair won't last more than a week.

Naturally, once you've assembled the right side frame and stashed it away to dry, you'll be ready to whip together the left unit. Believe me, I don't use the words whip together lightly; I can complete a side in just a few minutes, and now that you've had some practice, you should be able to, too.

A Day Passes ...

You're champing at the bit to get your chair finished, right? Well, nothing could be easier. Just position the seat slats 1/2" apart across the side frames. Mark where the slats overlap the top rails (each end should extend outward by 3/4 of an inch), apply glue to the marked areas, and hammer the slats in place, using a pair of 2" finishing nails at every joint.

You'll need to exercise some patience when you attempt to attach the first few slats, because you'll have a hard time keeping the side frames upright and aligned while you hold the slat in place. Even if you can't get someone to help you steady the components, though, you'll be home free as soon as the first couple of slats are nailed down and the chair gains some rigidity. Make a point, however, to check each slat with a try square to make sure it's perpendicular to the frames.

When you've finished the seat slats, go ahead and tack on the back crosspieces. Position the first one so that its bottom edge is 5" above the seat, and space the remaining three pieces 1/2" apart, with the ends extending 1 1/2" beyond the supports.

Now, before you flop your carcass onto your newly built handiwork, nail the front and back bottom braces (parts G) in position. Place each one so that its bottom edge is pretty much even with the top edge of the bottom rails (B). Give the whole thing another 24 hours to dry, and then you and your chair will be ready to meet seat to seat.

I didn't apply any finish at all to my rustic set of four yellow-poplar dining chairs, because the lumber came from the floor of a 100-year-old house, complete with gouges and nail holes, and I liked the look. The functional simplicity of the furniture seems to call for a natural treatment, so I just sanded the quartet slightly and left them "as is." (EDITOR'S NOTE: Our staffers chose to use a medium-dark wood stain, thinned with a bit of boiled linseed oil, to color the truss-worthy chair they built of 1 x 2 pine.)

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