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.Â* Its only a few tenths to a couple thou depending on the blow, but it does move.Â* 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.Â* I tend to mount a vise or in this case two vises and only remove them if I have to.Â* Often even temporary fixture plates are just mounted in the vises.Â* The two I just remounted on the table were last off the machine over a year ago.Â* I've cut a lot of parts in those vises.Â* 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.Â* I know a crash with a fly cutter could do as much damage as a hammer.Â* 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.

--
Bob Nichols AT comcast.net I am "RNichols42"