Visual Thread Inspection of Form Threads

Visual Thread Inspection of Form Threads

When using form thread taps it is important to be aware that form threads visually have a slightly different look than a cut thread.  All formed threads have a cup or “U” in the crest due to the nature of the thread forming process.  A properly sized hole should result in a thread percentage of 65-75%.  Tapping with too small of a pre-tap hole size results in excessive tapping torque, tap wear and possible tap breakage.   Enclosed is a link on our website to a tapped hole size guide for rollform taps. (http://www.hutchisontool.com/pdf/tapped_hole_size_guide.pdf)