Many thanks to Mert, Gadgetbuilder and others for pointing out the
proper use of chucks.
Today I tested jaw positions on a three jaw chuck and the sequence-of-tightening by measuring the run-out
on a piece of 5/8" drill rod. The worst jaw positions
and using only one of the three tightening screws had 0.010" run out.
The best jaw positions had run-outs about 3 thou and
less. Then using the best tightening sequence the run-out
dropped to 0.0008".
This test was on the standard 3 jaw HF chuck that shipped with
my HF 8x12. I had previously tried all three positions of the
chuck on the back plate and selected the best of three before
doing the jaw test.
The alternate jaws, when tested were terrible on the smallest
diameter ( inner jaws need grinding ) but when gripping a 2.5" dia. test bar on the outer chuck surfaces the run-out dropped to 0.006"
at best. I suppose that one should not use the alternate jaws
until the work diameter exceeds about 1.5"
BTW the 4 jaw chuck from HF fits the spindle on the HF 8x
without having to make a special backing plate.
Regards,
Victor
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