Wood Joints Without Glue or Screws

Glue-free joinery is not a stunt. It is the correct approach when a piece must come apart for transport or repair, when seasonal movement would crack a rigid glue line, or when hardware would be exposed to weather and fail. The joints that work without glue share one property: they convert a pull or a racking force into compression against a shoulder or a wedge. A plain butt or miter has no such conversion, which is why those joints cannot be made glue-free no matter how carefully they are fitted.

What makes a joint hold without adhesive

Three mechanisms do the work. First, a shoulder bearing against a face: the tenon shoulder pressed against the mortised stile resists racking and keeps the joint square. Second, a mechanical lock: a peg through a drawbored tenon, a wedge through a through-tenon, a key through a tusk tenon, or a dovetail’s undercut. Third, friction from a tapered fit, which is why a well-cut sliding dovetail stays put without a drop of glue.

A joint that relies only on friction between two parallel faces will loosen. A joint that relies on a shoulder alone will rotate. The reliable glue-free joints combine at least two of the three.

The joints that work

Drawbored mortise and tenon

The mortise is cut, the tenon is cut, and the peg hole in the tenon is offset toward the shoulder by a small amount relative to the hole in the mortise cheek. Driving the peg pulls the shoulder tight against the stile and keeps it there. The offset is the whole trick: too little and the peg does nothing, too much and the tenon splits or the peg shears. There is no universal offset; it is a small fraction of the peg diameter, judged for the species and tested on a scrap joint first.

Drawboring suits frames, doors, and benches that will be moved. It is not reversible without driving the peg out, so it is a semi-permanent joint rather than a knock-down one. See the drawbore mortise and tenon guide for the offset and peg sizing in detail.

Wedged through mortise and tenon

The tenon passes through the mortised piece and is slotted to accept one or two wedges. The wedges spread the tenon end, locking it in the mortise and pulling the shoulder tight. This is the standard joint for trestle table bases, sawbenches, and timber frames.

Wedge orientation is where this joint fails. The wedges must run in line with the grain of the mortised piece, not across it. A wedge driven across the grain of the mortised member acts as a splitting wedge and will open a crack along the stile or leg. Mark the grain direction on the mortised piece before cutting the tenon slot, and cut the slot to match. Two wedges spread apart in the same grain direction are stronger than one central wedge and less likely to split the tenon.

Tusk tenon (keyed tenon)

A tusk tenon passes through the mortised piece and is locked by a separate key, called a tusk, driven through a slot in the tenon on the far side. The tusk bears against the outer wall of that slot and against the far face of the mortised piece, drawing the shoulder tight. Knock the tusk out and the joint separates. This is the joint for knock-down furniture: trestle tables, workbenches, bed frames that must be carried through a doorway.

Leave plenty of tenon beyond the slot: the tusk pushes against that short length of end grain, and if too little is left it shears off. Cut the slot so its inner edge sits slightly inside the face of the mortised piece, so the tusk bears on that face rather than bottoming in the slot. A tusk that fits loosely will work its way out under vibration; a tusk with a slight taper driven home will stay.

Sliding dovetail

A dovetail-shaped tenon slides into a matching tapered housing cut across or along a board. The undercut resists pulling out perpendicular to the housing. Used for carcase shelves, dividers, and battens across tabletops. Cut the housing slightly tapered in width so the joint tightens as it is driven home, and stop the housing short of the end so the joint cannot slide through.

A sliding dovetail is not a knock-down joint. Once driven home it is rarely taken apart again. See the sliding dovetail joint guide for the taper and the housing depth.

Bed bolts and knock-down hardware

Bed bolts, cross dowels, and connector bolts are the hardware middle ground. They are not joinery in the traditional sense, but they allow a frame to be assembled and disassembled repeatedly without the fit tolerance a tusk tenon demands. The bolt passes through a hole in one member and threads into a cross dowel in the other. The joint relies on the bolt and the bearing of the two faces, so the faces must still be cut flat and square. Hardware does not excuse a bad fit.

Glueless joints compared

Cutting by hand

Cut the mortise first with a mortise chisel, chopping a through mortise from both faces to avoid blowout, then mark and cut the tenon to fit the mortise that exists. A tenon cut to a mortise that already exists can be tuned with a shoulder plane; a mortise cut to an existing tenon cannot be enlarged easily.

For a through mortise, mark the same face on both sides of the stile and chop from both faces toward the middle. For a wedged tenon, cut the slot before fitting, not after, so the tenon can be test-fitted with the wedges in place.

For a sliding dovetail, cut the housing with a router plane or a saw and chisel, then cut the dovetail on the end of the shelf to match. Test the fit at the open end of the housing, where the taper is widest, before driving the joint home.

Cutting by machine

A router with a spiral upcut bit and a guide bushing cuts a clean mortise, but with rounded ends that must be squared with a chisel or matched by rounding the tenon. A hollow-chisel mortiser cuts square-ended mortises and speeds up repeated ones. A single dovetail bit cuts both the housing and the key of a sliding dovetail, in separate set-ups. A tablesaw with a dado stack cuts the tenon cheeks and the through-tenon slot.

Machine-cut joints still need hand fitting. The machine establishes the geometry; the shoulder plane and the chisel establish the fit. A joint that comes off the machine and goes straight into assembly without a test fit will either be too tight and split on driving, or too loose and rely on glue that is not there.

Judging the fit

A good glue-free fit has three properties. The shoulder bears evenly all around; check with a straightedge or a smear of chalk on the shoulder, then assemble and look for a transfer mark. The tenon bears on the cheeks, not on the end grain of the mortise floor. The peg, wedge or tusk seats with firm mallet blows rather than heavy hammering, and the joint stays closed without a clamp.

A bad fit shows as a shoulder that closes on one side and gaps on the other, a tenon that rocks in the mortise, or a peg that drives easily and does not pull the shoulder tight. Any of these means the joint will loosen under load. Fix the shoulder first; a shoulder that does not bear cannot be compensated for by a tighter peg.

Where glue-free joints fail

Three failures account for most of them. The first is a shoulder that does not bear, which lets the joint rotate and eventually splits the mortised piece at the peg or wedge. The second is a wedge or peg driven across the grain of the mortised piece, which splits it along the grain. The third is a joint used where it does not belong: a plain butt or miter has no mechanical lock and cannot be made glue-free, and a sliding dovetail in a member too narrow to leave cheeks will tear out.

Outdoor work is a special case. Glue-free joints that rely on friction will loosen as the wood moves with the seasons, so pegs and wedges should be re-driven periodically. A drawbored joint in outdoor furniture should be pegged with a durable species and the peg ends left slightly proud so they can be trimmed back after re-driving.

The mistake most often made

The most common mistake is cutting the mortise and tenon to a nominal size and assuming the fit will follow. It does not. The fit is established by the shoulder and by the peg or wedge, and both must be cut to the specific piece of wood in front of the bench. The reason this happens is that machine setups encourage cutting all the mortises at one setting and all the tenons at another, which produces a consistent but not necessarily correct fit. A joint that fits one stile will not necessarily fit the next, because the stiles are not identical in thickness or in grain direction.

A second common mistake is cutting the wedge slot after the tenon is fitted. The slot changes the tenon’s stiffness and its fit, so a tenon that fitted before the slot was cut may not fit after. Cut the slot first, fit the tenon with the slot in place, then cut the wedges to match.

When to use glue-free joinery and when not to

Use it when the piece must come apart, when the joint must allow seasonal movement, when hardware would be exposed and fail, or when the joint will be re-driven periodically. Do not use it for a plain butt or miter, for a joint in a member too thin to take a peg or a housing, or for a joint that will be hidden and never serviced. A glued joint in a hidden location is not a compromise; it is the correct choice. Glue-free joinery is a solution to specific problems, not a standard to which all work must be held.