Technical Information
Ground Thread Tap Limits
In addition to the nominal size and pitch of a tap, there is another
important dimensional factor to be considered when selecting a
ground thread tap for a given job. This factor is the pitch diameter
tap limit, “H” and “L”. “H” represents (high) above basic pitch
diameter; “L” (low) is below basic pitch diameter. Tap limits have
been established to provide a choice in the selection of the tap size
best suited to produce the class of thread