Carpentry Joints and Fastening Methods
Scope
This domain tests the joinery families, where each is used, and the correct fasteners and adhesives for a given assembly.
Joint families
- Edge or width joints: butt, dowel, biscuit, tongue and groove, loose tongue, rubbed joint.
- Length joints: half lap, scarf, finger, bridle.
- Frame joints: mortise and tenon (through, haunched, stub), dowelled, bridle.
- Carcase joints: rebate, housing (dado), through dovetail, half-blind dovetail, comb or finger joint.
- Angle joints: mitre, mitre with spline, half lap.
Dovetails resist pulling apart in one direction and suit drawer boxes; a haunched tenon stops the mortise showing at the edge of a door stile; a housing carries a shelf.
Fasteners and adhesives
Nails: wire, oval (less splitting), cut; clench where withdrawal matters. Screws: countersunk, round head, chipboard, twinfast; length about 2–2½ times the thickness of the piece being fixed; pilot hole in hardwood. Adhesives: PVA (interior, porous), cross-linked PVA (semi-exterior), urea formaldehyde (interior, heat-resistant), resorcinol or polyurethane (exterior), contact adhesive (laminates), epoxy (gap filling). Dowels, biscuits, confirmats and cam fittings for knockdown work.
Worked example
A drawer front should show a neat dovetail on the side but no end grain on the face. Choose a half-blind dovetail, with pins cut on the drawer side and sockets cut only partway into the front.
Traps
Gluing end grain as if it were long grain (it is porous and starved of glue - size it or use a mechanical joint); driving a nail near an edge without a pilot hole; using interior PVA on external joinery; over-tightening cramps until the glue line is starved.