Concealed wedged-tenons add behind-the-scenes strength
Historical, utilitarian furniture is one of my favorite sources for design inspiration, and the vernacular fireside stools of Northern Europe are especially appealing for their dainty yet sturdy stances. Traditionally used as a perch for creeping close to the warmth of a hearth or tending to a fire, these simple stools’ short stature and splayed legs pack a lot of character and woodworking skills into a quick project. My take on these fireside stools features a thick seat with chunky legs attached via fox-wedge joints. I wanted to use a connection that would be as strong as a classic through wedged tenon joint, but with a clean look that doesn’t call attention to itself. The fox wedge is a blind joint with a wedge hidden inside. During final assembly, you gently pre-load the wedge into the tenon part-way, and then drive the tenon into the mortise. As the wedge hits the bottom of the mortise, it is driven further into the tenon, causing the tenon to flare and lock the joint. But beware. If the wedge is too large, or if it breaks inside the joint as you hammer it in, the tenon will get stuck and never fully seat. Exciting, right? Fox-wedge joints can be intimidating, particularly if they are part of a larger project that you’ve put months of time into. This quick little stool is a low-risk, high reward setting for learning and practicing a powerful, hidden joint.A simple seat with hidden complexity
Three short, stout legs support a thick demilune seat to create this sturdy stool. Wide legs taper to round tenons, which fit into deep, angled mortises in the seat. At the time of final assembly, the tenons are secured with blind wedges inside the joint. These “fox-wedge” joints provide a strong, hidden structure. I used orchard-sourced Claro walnut for the legs and seat, and white ash for the wedges.
Order of Work
- Make the legs
- Make the seat and wedges
- Assemble and finish
Make the legs
Prepare three 2 × 2 × 12" blanks for leg stock, plus additional blanks for set-up. Mark the center on one end of your set-up stock. Using a compass, place the needle at one corner of the blank and the pencil at the center, then draw an arc from edge to adjacent edge. Repeat at all four corners to lay out the points of an octagon. With your table saw blade tilted to 45°, use these layout marks to set your fence, and then rip the leg stock into octagons.
At one end of each leg, use a combination square to mark lines offset 1⁄2" from each of the eight edges, generating a smaller octagon. Taper the legs to these marks with a hand plane. Cut 11⁄2" long tenons at the narrow ends, and then use a spokeshave to round each leg and fair the transition between leg and tenon. After laying out the fox-wedge joint kerf line and drilling a relief hole for each leg, saw the kerfs as shown.
One setting, four cuts, eight sides. With the table saw blade tilted to 45°, use setup stock to dial in the fence location for ripping the legs into octagons. Rip all four corners of each blank to create octagonal stock.
Taper the octagons. Work all eight sides evenly, frequently rotating the stock as you plane to the layout lines. I like to use a white chalk pencil to make layout marks when working with a dark wood like walnut.
Chamfer to fit. Secure each tapered leg in your bench vise with auxiliary wedges. Using a file, chamfer the tenon end for an easy fit in the tenon cutter for the next step.
Cut the tenons. Use a wedge to level the leg and clamp it in place. Chuck a tenon cutter in your handheld drill and then size the tenon of each leg in turn.
Round them out. A bench hook with a v-groove or trough, as shown, does a great job of stabilizing the legs for spokeshaving. Round each leg without removing too much material from the foot-ends and taking care not to cut into the tenons.
Kerf the tenons. Add v-grooves at the table saw to your auxiliary wedges to clamp around the now-round legs. Lay out the kerf line for the fox-wedge joint and drill a 1⁄8" hole at the bottom of kerf. Choose a saw that will create a fairly wide kerf, mine is 1⁄16", and saw down the line.
Shape the seat and cut the wedges
Refer to the Seat Plan diagram (above) to lay out the seat shape and mortise geometry on a 23⁄8"-thick blank. Using the layout lines and a bevel gauge as guides, drill the 1" dia. × 13⁄4" deep mortises into the seat bottom, as shown. Saw the curve of the seat shape at the bandsaw, clean up the saw marks with a low-angle block plane, and spokeshave a 1⁄4" chamfer along every edge of the seat. Saw the wedges using straight-grained timber (I used ash). Use a chisel to smooth the faces of the wedges and trim to final length and width.
Angle the mortises. Start with the bit held vertically at the center of each mortise. As you drill downward, slowly pivot the drill along the direction line until it coincides with the 15° angle on a T-bevel and then plunge to full depth.
Chamfer the seat edges. Lay out the chamfer’s bounding lines, and then trim away the material using a spokeshave in clean, angled strokes with the grain. On the curved edges, begin at the apex, shaving toward each end.
Saw the wedges. For speed, I prefer to saw wedges by eye and hand, making several more than would be necessary for the piece. From among these, I choose the wedges that most closely match the wedge thickness I’m aiming for and then trim to final size.
Assemble with confidence
Due to its geometry, the fox-wedge joint can be assembled only once. If this is your first attempt at this joint, mock up practice joints to get the hang of it. Once you have begun the stool’s final assembly, proceed with precision and confidence. Apply glue to one mortise, tenon, and wedge at a time. Load the wedge into the tenon’s kerf far enough to stay put but not widen the kerf. With the wedge oriented perpendicular to the grain of the seat, use a mallet to drive the tenon-wedge assembly into the mortise, until the leg is fully seated. Repeat this process with each leg. Wait at least a half hour before trimming the feet, using the technique described in this issue’s Tips & Tricks (Scribing to level), p 18. Sand and finish. I used Osmo Polyx-Oil in clear satin.
