Veritas Saddle Square — and the Amazon Alternative

The error a saddle square exists to prevent is small and extremely common. You mark a crosscut line across the face of a board with a try square. Then you turn the board on edge, reset the square, and mark down the edge — and the two lines do not quite meet at the corner. Cut to the wrong one and the shoulder is out of square by exactly that much.

A saddle square is a square bent through 90 degrees. It sits over the corner, referencing the face and the edge at once, so one placement gives both lines and they meet by definition.

Veritas’s version is sold by Lee Valley direct. The Shinwa scored here is the Amazon equivalent, in aluminium, with 45-degree faces as well as 90.

Where it earns its keep

Dovetail layout, primarily. Marking the baseline around a board, and marking tails down from the end grain, is exactly this problem repeated a dozen times per joint.

Tenon shoulders, for the same reason. And any crosscut on stock thick enough that you will saw from two faces.

The 45-degree face is worth having: laying out a mitre on the face and the edge has the same continuity problem, and this solves both with one tool.

Aluminium, and what it means

Aluminium is soft enough that a marking knife run along the same edge hundreds of times will eventually cut into it. Once the reference edge has a groove in it, the knife follows the groove instead of the edge and your line is no longer straight.

Two ways to live with it: vary where along the edge you register, and inspect the edge occasionally under a light. A steel square does not have this problem, which is part of what Veritas is charging for.

The limit nobody mentions

A saddle square is short. It references a small patch of the edge, so if the edge is bowed, the square sits on the bow and the line inherits it. Joint the edge first for work that matters — a layout tool cannot correct a surface, only copy it.