F/T

Full thread guards keep wheels from entangling hair and debris, promoting long life.

Add the chamfer length to the required full thread depth from the print: 1.0 + 0.3636 = 1.3636 (Z-1.3636)

A full thread form is produced to the last thread; there is no tapered lead as required with a tap.

Defective valve heads will have only six full threads. Good valves will have eight or more full threads.