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PM-1030V v5 2020-10 Copyright © 2020 Quality Machine Tools, LLC
Figure 3-26 Threading dial visualization for selected U.S. threads
GENERAL RULES FOR THE THREADING DIAL
If the TPI value gives a whole number when divided by two,
you can re-engage the half-nut on any line, also mid-way be-
tween the numbered lines on the dial (marking the mid-points
will give you double the number of re-engagement choices).
Special cases: if the ÷ 2 result is an even whole number, ex-
ample 12/2 = 6, there are even more re-engagement choices,
see the visualization chart above. This may not be usable in
practice due to the diculty of estimating the exact point to
re-engage. If in doubt, re-engage on the start line!