Position your workpieces at the correct angle prior to welding. These squares have an extra-wide head, so you can clamp them in place.

Squares with joint access cutouts make it easier to reach joints, such as when welding and gluing. Those with locator holes help you align your workpiece on a welding grid. They have 5/8" locating holes on 2" centers to fit into standard fixture table configurations. Leveling tabs are for aligning workpieces with one another.

Aluminum squares are lightweight and corrosion resistant. Cast iron squares are durable and difficult to dent or scratch. They resist weld spatter, but they’re more likely to corrode than aluminum. Black-oxide steel squares are stronger than aluminum and more corrosion resistant than cast iron.