Knurls are grooves cut into a cylinder either to improve someone’s grip or simply for decorative purposes. According to “Machine Trades Blueprint Reading” by David Taylor, knurls are made by impressing a straight, cross or diamond shaped pattern into a cylindrical piece. The American National Standards Institute or ANSI creates standards for American manufacturing processes and tools, including knurling.
ANSI standard 94.6 is the diametrical pitch inch-knurling standard. Standard 94.6 is maintained by the American Society of Mechanical Engineers (ASME) and then approved by ANSI as the American standard. The ANSI standard includes recommended dimensions for the knurled grooves and spacing of the grooves.
ASME standard Y14.5M has been adopted as ANSI standard Y14.5M. This standard gives geometric tolerancing guidelines for machining operations such as inch knurling.
Knurling can be done with a lathe with a knurling tool attached. The knurling tool is then pressed into the rotating cylinder to create the knurl pattern. Lathes are covered by ANSI standard B5.9. ANSI standard B5.9 pertains to spindle nose tools (such as knurling tools) used to cut metal on lathes. Knurling can also be done on an automatic screw machine. Straight knurls have a circular pitch. Diamond and spiral shaped patterns have a diametral pitch.