Form general purpose ACME threads. These high-speed steel taps are for use on most metal and plastic. With a square shank, they're compatible with tap holders for drill presses and milling machines. Also known as tandem taps, these have an extended chamfer with two sets of chamfered cutting threads. Because these sets of threads have different shapes, reversing the tap for removal may cause damage to the work piece and is not recommended.
Use these taps with a rigid setup to tap through holes only. ACME screw threads were devised to allow rotary and transversing motion on machines; and are also used in jacks, valves, presses and other mechanisms where heavy loads are encountered. The ACME thread is characterized by a 29° included angle. ACME taps typically require specialized engineering and design due to the nature and severity of cut required in producing ACME threads.
