What's inside
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A three-legged stool is stable on an uneven floor because all three feet can touch the ground without rocking. The build is straightforward, but the leg joints need accurate angles and tight-fitting wedges. This plan makes a low stool about 18 inches tall with a 12-inch seat; adjust the dimensions to suit your use.
Contents
Materials and tools
Use straight-grained hardwood for the legs and seat. Ash, maple, and oak are durable choices; clear, dry softwood can work for a light-duty stool, but dents more readily. Avoid knots near the joints. The dimensions below assume stock at least 1 inch thick for the seat and legs roughly 1 1/4 inches square.
- One seat blank, about 13 inches square by 1 1/4 inches thick
- Three leg blanks, about 1 1/4 inches square by 19 inches long
- Hardwood wedges, cut from straight-grained offcuts
- Drill press or a hand drill with an angle guide, a 5/8-inch bit, saw, chisel, mallet, square, and measuring tools
A drill press makes the angled mortises easier to repeat, but a well-made drilling guide and careful layout are adequate. A 5/8-inch brad-point bit helps start cleanly on the seat’s underside. For shaping, a spokeshave is pleasant to use, while a rasp and sanding block cost less and work fine.
Choose the joint and leg layout
This design uses wedged through-tenons: each leg passes through a tapered mortise in the seat, and a wedge spreads the tenon below the seat. The wedge locks the joint mechanically. Glue adds security, but it cannot rescue a loose, badly angled fit.
| Approach | Best for | Trade-off |
|---|---|---|
| Wedged through-tenons | A durable stool with visible joinery | Requires accurate angled mortises and careful wedge fitting |
| Round legs in drilled holes | A simpler, quick build | Less room for error only if the holes and leg ends fit closely; joints are harder to adjust once glued |
| Metal brackets or screws | Utility seating where appearance is secondary | Fast assembly, but exposed hardware and looseness can be concerns over time |
Lay out the three legs evenly around the seat, with their centers on a circle about 4 inches in diameter. Keep each center at least 2 1/2 inches from the seat edge. Splay the legs about 10 degrees from vertical in the direction that gives a wider footprint. Mark the direction of each mortise on the underside; all three must lean consistently.
Drill and shape the mortises
First flatten the seat blank and mark its center and leg positions. Set the drill angle to 10 degrees and make a test hole in scrap of the same thickness. A useful check is to insert a straight dowel and confirm that it leans the intended way. The top openings should be about 5/8 inch across; the openings on the underside will be slightly elongated because of the angle.
Drill from the underside toward the top, stopping just as the bit breaks through. Finish the opening from the top to reduce tear-out. Chisel each hole into a tapered mortise: about 5/8 inch wide at the top surface and roughly 3/4 inch at the underside. Keep the long axis aligned with the leg’s direction of lean. Work gradually and test with a leg tenon; the tenon should enter snugly by hand, not require heavy hammering.
Support the seat securely while drilling. A seat that shifts can spoil the angle or catch the bit. If the hole wanders, do not enlarge the entire mortise to hide the error; that leaves a weak, loose joint. A small correction with a chisel is safer, provided enough wood remains around the opening.
Shape the legs and tenons
Mark the tenon shoulders so each finished stool will stand about 18 inches tall. Leave the legs a little long until assembly; final trimming is easier after the seat is fitted. Shape the lower portions into a gentle taper, leaving the upper 4 inches full thickness for strength. Break sharp edges with a rasp or plane.
Cut a tenon on each leg to match its mortise, usually about 1 1/2 inches long. Make the tenon slightly wider at its lower end than at the shoulder so it follows the tapered mortise. Leave the tenon’s end about 1/8 inch proud of the seat underside for wedge fitting. Mark a kerf down the center of each tenon, stopping about 1/8 inch short of the shoulder; a deeper cut can split the leg.
Dry-fit all three legs before applying glue. They should seat fully with no visible shoulder gaps, and their splay should point outward rather than twist around the stool. If a leg rocks in its mortise, adjust the tenon, not the whole hole. A wooden mallet and bench chisel set is useful for this fine fitting, though sharp chisels you already own are enough.
Fit wedges and assemble
Cut wedges from straight-grained hardwood, about 1 inch long and 1/8 inch thick at the wide end, tapering to a thin but not fragile edge. Their grain should run along the length of the wedge. Test each wedge in its kerf: it should spread the tenon without bottoming out before the tenon bears against the mortise walls.
Apply a modest amount of woodworking glue to the tenons and mortises. Seat the legs, then drive each wedge with light mallet taps. Alternate between wedges and check that the legs remain aligned. Stop when the wedge is firm and the joint closes; excessive force can split the tenon or lift the seat fibers. Trim the protruding tenons and wedges after the glue cures, usually overnight, then pare them flush.
Level and finish the stool
Set the stool on a known-flat surface and mark the longest leg. Trim the feet in small amounts until all three touch without rocking. Sand the seat and legs through 120 and then 180 grit. Ease the seat edge with a round-over bit or sanding block; a sharp edge is uncomfortable under the thighs.
Use a hard-wearing oil or wiping varnish for a simple finish. Apply thin coats according to the product directions and let each coat dry fully. Before regular use, inspect the joints for gaps and press down firmly on the seat. If a joint moves, stop using the stool and repair the fit rather than relying on another coat of glue at the surface. A wiping varnish is a practical choice for a stool that will see frequent handling; oil is easier to renew but offers less surface protection.