ACME vs Trapezoidal Threads: The Difference

ACME and trapezoidal threads look alike but are different standards. ACME has a 29° thread angle and follows ASME B1.5. Trapezoidal (Tr) has a 30° thread angle, is metric, and follows DIN 103-9.

Where they are used

Both are power-transmission threads, used on parts such as lead screws that carry motion or load.

Tolerance classes

ACME is specified in classes 2G, 3G and 4G, where 3G and 4G give less backlash. Trapezoidal uses 7H / 7e for medium quality and 8H / 8c for coarse quality.

Why the gauge has to match

The small angle difference and different tolerance systems mean one gauge cannot check the other. See our ACME and Stub ACME gauges and trapezoidal gauges.