Not for nuthin'…. But….. a joint that only trusts glue is a joint that's going to let you down the first winter the shop door stays open. Drawboring fixes that with a hole, a hair of offset, and a split oak peg. Same trick that's kept old barn frames and 17th-century New England joined chests tight for a few hundred years.
Why it matters: In a drawbored mortise-and-tenon you bore through the mortise cheeks, then bore the tenon's hole a little closer to the shoulder. Drive a tapered peg through the mismatched holes and it bends, hauls the shoulder tight, and keeps the tenon in tension as the wood shrinks and swells. No clamps needed, which is handy on a long stretcher. No glue needed either, which matters when a joint lives out in the weather and water gets in and eats the glue. Timber framers count on it to keep frames tight through the racking of raising day and the shrinkage that follows. That's exactly the abuse boat-shop horses, building stands, strongback legs and cradle frames take. A dory gets rolled over on them, a hull gets slid across them, and half the time they spend the winter out in the yard. WoodenBoat's gallery of boatbuilders' sawhorses keeps coming back to the same thing: let-in joinery that fits tight and solid stock. Drawbore those joints and they don't get wobbly with age.
Materials
- White oak or ash for the frame. Today's example joint: a 3½″ × 3½″ leg and a 1¾″ × 3½″ stretcher with a ⅝″ × 3″ × 2½″ tenon.
- Dry, straight-grained white oak offcuts for pegs, riven (split), not sawn. Ash and hickory make good pegs too. For gear that lives outside or in the damp, timber framers favor rot-resistant white oak or black locust.
- A candle stub or block of paraffin to wax the pegs
- Glue: optional (see step 7)
Tools
- Mortise gauge, chisels or a mortiser, backsaw
- Brace and ⅜″ auger, or a drill with a ⅜″ brad-point bit, plus a backer board
- A thin, sharp awl (or the bit's own point) and a marking knife or sharp mechanical pencil
- A steel drawbore pin. A machinist's alignment pin set in a wooden handle works fine, and a nail set will do for ¼″ pegs.
- Froe or a stout knife and a mallet for riving, a chisel or drawknife for shaping, and a dowel plate (optional)
- Flush-cut saw
Steps
- Cut the joint and fuss over the shoulders. Drawboring forgives a so-so cheek fit, but the shoulder has to seat dead square and tight against the leg. Size it sensibly. The timber framers' standard keeps peg diameter at or under ⅔ of the tenon thickness, so a ⅜″ peg wants a tenon at least 9/16″ thick (our ⅝″ is fine). Their rule of thumb is a tenon at least twice as long as it is thick if it's going to be pinned.
- Bore the mortised piece first. Bore a ⅜″ hole clean through both cheeks, centered ⅜″ from the mortise edge in furniture and ½″ in bigger work like benches, doors and shop stands. Center it on the tenon's width, well away from the tenon's edges, and leave plenty of tenon past the peg. Timber framers want at least 4 peg diameters of wood beyond the hole on any joint that might pull in tension. On our joint the hole sits 2″ from the end of the tenon, and 4 × ⅜″ is only 1½″. Go slow and use a backer board. In Follansbee's experience, when oak splits it's usually during the boring, not the pegging. A wide tenon gets two pegs so the joint can't pivot.
- Mark the tenon through the hole. Seat the joint all the way home, then stick the bit's point or a thin awl into the hole and prick the center on the tenon cheek.
- Move the mark TOWARD the shoulder, then bore. This is the whole trick, and the sources don't agree on the amount, so here's the honest range. Moxon's "thickness of a shilling" works out to about 1/16″, and that's where Paul Sellers and Follansbee's joint-stool book start. Chris Schwarz prefers 3/32″ for furniture and pushes toward ⅛″ on big joints in tough oak, ash or elm. Peter Follansbee uses about ⅛″. Fine Woodworking's door builders go a fat 1/32″ with ¼″ pins. Timber framers using 1″ pegs run about 3/32″ in hardwood and ⅛″ in softwood. For a ⅜″ peg in an oak stand, start at 1/16″ on a scrap joint and work up to 3/32″. Sight through the assembled joint, and the offset should cover about a quarter to a third of the hole. Mark with a knife, because a fat pencil line can wander 1/32″ on you.
- Rive and shape the pegs. Split dry, straight-grained oak into sticks a hair over ⅜″, then shave them octagonal or drive them through a ⅜″ dowel plate. Taper the business end. Schwarz tapers the last ½″ down to a ⅛″ tip, and a longer taper (up to about 1″ on this joint) threads a bigger offset more easily. Make the peg long enough that the full-diameter body reaches the far cheek and the taper comes out the far face. About 5″ does it for a 3½″ leg. Store-bought dowel is OK only if the grain runs dead straight, and then use less offset.
- Test with the drawbore pin. Ease it in. Schwarz twists his rather than striking them, and a light tap is as rough as it should get. It pulls the joint up, shows you the fit, and opens a path for the peg. If it fights you hard, ease the tenon hole a touch. If it slides through with no draw, make a fatter peg.
- Wax it and drive it. Rub the peg with paraffin (an old timber framer's trick), head end up, and make sure the tip has started into the far cheek before you swing. Drive until the resistance builds and the sound changes, then stop. Don't beat it flush. Saw it flush afterward. Glue is your call. Schwarz still glues most joints and even coats the peg. Follansbee uses none. On horses that live outdoors, the peg is the thing doing the work anyway.
MOAM's shop note: The classic blunder is moving the tenon hole the wrong way, away from the shoulder. Then the peg shoves the joint open, and Fine Woodworking calls that one an easy mistake "with the direst of consequences." Second blunder: too much offset on your first try, which gives you an exploded peg or a split tenon. Cut one scrap joint first. Pro trick from Schwarz: use a coin as your offset gauge. A penny is .056″ (call it 1/16″) and a nickel is .072″ for a heavier draw. Moxon used a shilling. In Marblehead we'll settle for a nickel.
Sources: Christopher Schwarz, "Drawboring Resurrected" and related posts (Popular Woodworking); Peter Follansbee, "The Indispensable Mortise & Tenon" (Popular Woodworking) and his Joiner's Notes blog; Alexander & Follansbee, Make a Joint Stool from a Tree (Lost Art Press); Fine Woodworking drawbore articles; Paul Sellers; Sobon & DeStefano, TFEC Timber Design Guide 20, "Draw Boring of Pegged Joints," and the TFEC 1-2019 Standard (Timber Frame Engineering Council / Timber Framers Guild); WoodenBoat, "Sawhorses."
MOAM Out.











