Tenon saw

Also called: back saw, backsaw

A tenon saw is a backsaw, a saw whose blade is stiffened along its top edge by a folded strip of metal, sized for cutting tenons and other close joinery work. Its blade plate typically runs fourteen to nineteen inches long, with eight to ten teeth to the inch, and it is counted among the principal saws for dividing wood, alongside ripsaws, panel saws and several others.

Size and kit

A dovetail saw is essentially a small tenon saw, roughly six inches long, kept for finer work, and a tool case should be sized so the tenon saw itself fits within its lid. In one modest tool kit thought sufficient for a specific job, it appears alongside only a mitre block, a shooting-board, a trying plane, a hammer and bradawls.

Cutting a tenon

Shoulders are cut first, leaving half the scribed line and undercut a small amount so the joint faces close up tightly at the front. Once the shoulder cuts are made, or nearly to full depth, the cheeks are then sawn with the tenon saw or a backsaw. On the rip-toothed version used for cutting cheeks, the longer the blade stays in the kerf, the saw's own cut, the greater the risk of an inaccurate cut, so it must stay very sharp; tenon shoulders, by contrast, are cut with a fine-toothed version of the saw. Hasluck (1907) gives the finishing steps directly: "Having finished wedging up, take off the cramp, oil the tenon saw with olive oil (not linseed), and cut off the projecting ends of the tenons and wedges."

Other joinery cuts

For a housing joint, a slot cut across a board to house another piece, the front tip of the saw, called its toe, cuts along marked lines down to the required depth, and the saw also cleans up the joint's nosing and cut edges once it is formed. Cutting is often begun in a small starting channel: the rail is secured against a bench stop or held in the vice, a channel is cut to guide the saw, and the saw is kept upright by guiding the blade with a finger. Fairham (1920) is direct about it: "In the small channel thus made place the tenon saw and, guiding the saw blade with the finger so as to keep it upright." Once lines have been sawn down each side to the required depth, the waste core is roughly chiselled out. A depth stop can be fitted to the saw by drilling holes slowly, so as not to soften, or lose the temper of, the blade, or simply clamped on instead. The saw can also be inserted into an existing cut to saw through a moulding, and kerf cuts made with it are typically spaced roughly twenty-five to fifty millimetres apart.

Care and improvised uses

In a pinch, shop-made cutters for a scratch stock, a simple homemade tool that scrapes a profile by dragging a shaped cutter along a fence, can be ground from scrap thin steel, including a piece of a tenon saw's own blade filed to the needed shape.