The Starrett 284 Acme Standard Screw Thread Gage is a standard for grinding and setting tools when cutting Acme threads in, which have the same depth as square threads but the sides of the threads are at an inclination of 14-1/2 deg. This form of thread is used extensively and has in many instances replaced the square thread in machine construction. The advantages of the Acme thread is its strength and the ease by which it can be cut compared with square threads.

Starrett® Screw Thread Gage, Acme Standard, Series: 284, 1 to 10 TPI Measuring, 29 deg Thread, Steel, Black Penetrate, 3-3/8 in L x 1-5/8 in W Dimensions