Help for going straight

A new method for inspecting out-of-straightness limits for machine, tapping, and thread rolling screws has been introduced by the Industrial Fasteners Institute (IFI) in standard IFI-138. The new standard "Straightness Gaging Method and Straightness Limits for Machine, Tapping, and Thread Rolling Screws," is included for the first time in the 7th Edition of Inch Fas-tener Standards reference book published by IFI. The new practice includes fully threaded screws, or screws with thread lengths of at least 4D and screw lengths to and including 12 inches. For screws with longer lengths and/or with shorter thread lengths, straightness limits are as agreed upon between manufacturer and purchaser.