Machinist Square – What Shape Are Your Parts?

If you’re a new or home machinist, learning how to square your parts is one of the first skills you should develop. A machinist square is one of the common tools every machinist should have.

Machining a square part on a manual milling machine is a fundamental exercise. As you begin producing parts with tighter tolerances, flatness and perpendicularity become increasingly important. Parts that become trapezoidal because of tool deflection may be rejected.

Choosing a Machinist Square

A good machinist square should be perpendicular and flat within a tolerance of 0.0002 inches. It should also be calibrated periodically to ensure that it remains within specification.

Squares are available in different accuracy grades. Grades A and B are common. Grade B is generally intended for users who do not require extremely close tolerances, while Grade A offers greater accuracy and is the preferred choice for precision machining.

A higher-grade square costs more, but accuracy is worth prioritizing when inspecting machined components.

Care and Maintenance

Handle a machinist square carefully. If it is dropped and develops a visible dent or bend, it can no longer be trusted for accurate inspection. The same care should be given to all precision measuring and inspection tools.