Multi-purpose Triangle Square (7"/178mm)

The shape does the work. It is a right-angled triangle with a lipped edge on one side, and that lip is what makes it fast: hook it over the edge of a board and the square is registered instantly with one hand, no aligning required. From there it marks a square crosscut line, a 45 degree mitre off the hypotenuse, and — by pivoting it on the lip — any angle in between using the graduated scale along the diagonal. That pivot function is how rafter and stair angles are laid out, and it is why carpenters carry one in a pouch.

It also works as a saw guide. Held against the board with the lip hooked over the edge, it gives a circular saw's baseplate a rigid fence to run against, which produces a genuinely square cut instead of a pencil line followed by eye. On site that single use justifies the tool.

At seven inches it is the standard size — small enough to live in a pouch or a back pocket, large enough to register properly on framing timber and boards.

It is aluminium, which is light, will not rust, and is stiff enough not to flex when a saw is pushed against it. It comes on a hang card.

The buyers are carpenters and framing joiners, roofing and stair carpenters, formwork carpenters, shopfitters and installers, general building trades, and hardware dealers, who sell speed squares in quantity.

Two points. Aluminium is soft, so a circular saw blade that wanders into the edge will take a bite out of it — keep the saw's baseplate against the square rather than letting the blade touch, and inspect the edge before relying on it, since a nicked edge no longer guides a straight cut.

And check the right angle occasionally with the flip test: hold the lip on a straight edge, scribe along the square arm, then flip the tool and scribe again from the same point. The lines should coincide. A dropped speed square can go out of true, and because it is used for every crosscut on a job, a small error is repeated everywhere. Ask us on WhatsApp for a price, singly or by the box.