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)
