On 9/11/2019 6:30 PM, Robert Nichols wrote: On 9/11/19 5:11 PM, Bob La
Londe wrote:
The point is even clamped down as hard as I dare the vises still can
move with only a modestly firm tap with a hammer. Its only a few
tenths to a couple thou depending on the blow, but it does move. I
know a hammer blow delivers a deceptively large amount of force, but
still. It made me wonder how easily those vises really move, and if
there was something I could do or even needed to do to more firmly
affix them in place. I tend to mount a vise or in this case two vises
and only remove them if I have to. Often even temporary fixture
plates are just mounted in the vises. The two I just remounted on the
table were last off the machine over a year ago. I've cut a lot of
parts in those vises. Maybe hundreds.

So what kind of "normal" cutting fores might cause those vises to
move. I put the word normal in quotes, not because I wanted only
include safe cuts that work every time, but also things that can
happen, but maybe shouldn't. I know a crash with a fly cutter could
do as much damage as a hammer. How abut a 1/2 inch mill entering a
piece of hard steel or a face mill banging on the edge of a work piece.

You aren't shifting the vise on the table, you are shifting the whole
table. Try putting the indicator on something else on the table while
you give the vise a whack.


That's likely part of it atleast. Remember I was going back and forth
between two vises and adjusting as I went. I was aware I might have
lost a step or two, but the steppers were at full power. I was not
doing it with the machine powered down. I suspect I could move the
table by hand (maybe straining myself a little) if it was powered down.