Vice alignment questions

Hello all,
Below you will find Bottle Bob's very helpful post on the subject,
reproduced without permission ;)
When tapping while translating, which I agree makes a lot of sense, the
stop condition is that the needle stops moving?? I do not expect to
care about the final reading, but I am wondering whether I am trying to
do too much in one pass.
I have been partially hindered by not having proper bolts for my vice,
so I was using clamps. That is now fixed, I think. I discovered that I
was getting fairly large (a few thous or more) movement every time I
adjusted a bolt. I am using washers; they are steel, but not
necessarily any particular hardness. Some attention to direction of the
force helped a little. I checked for junk under the vice, sorta checked
for whether it is warped (it sits quite solidly on the table). The gibs
came to mind, and some tension on them helped a bit. I also need to
make some new keys for my vice; they are too long, fit only one way, and
interfere with the bolts. They are removed at the moment.
With all of that, I was able to "easily" dial the vice with the new bolts.
While I have no intention of using a torque wrench on a regular basis,
could some kind soul either give me a ballpark torque, or use a torque
wrench to measure what "feels right"? Given a number, I can use a
torque wrench to get a feel for what I should be doing on this end.
Thanks!!
Bill
================
Bill:
Here is the meat of a post I made years ago in the CNC group.
Vise and part indicating.
What I do is clean the bottom of the vise and the machine table,
put
the vise on the table and move it around enough to scrape off any chips
into the t-slot grooves that might have gotten under it when lifting it
on the machine. I put the hold down bolts on and average out the play
forward and back and line it up as good as I can by eye. You're
supposed to clamp a large parallel block in the vise jaws simulating a
part and indicate off of that. I forego that step since Kurt vises are
pretty good about staying indicated whether there is a block in the vise
or not. I snug one bolt and start the indicator on the side of the jaw
closest to that bolt. I move the table and tap the vise while the table
is moving, and by the time the indicator has made one pass across (or
the vise has made one pass across the indicator - depending on your
point of view) it's pretty close. I then snug the OTHER bolt and loosen
the FIRST bolt and run the indicator back across fine tuning the vise as
it's moving. At the end of the travel it's usually indicated to a half
a thousandth. I tighten both bolts (you should have washers under the
nuts or the vise may move when you tighten the nuts. I do a final check
pass and that's it. It usually doesn't take more than two passes and a
final check pass to indicate a vise. DON'T wait to get to the other
end of the vise jaw to tap the vise, that is just a waste of time and
you'll end up having to move the table back and forth too many times
since the pivot point is not precisely at the end of the vise jaw but
beyond it a little.
The same thing with indicating parts, you snug one clamp and
start the
indicator near that clamp, tap your part while moving the table then
clamp the second bolt and loosen the first and tap while traveling back
the other way.
Some shops use key ways or dowel pins under the vises to align
them. I personally don't like that idea since the vise can be out a
thousandth
or two using keys and I hate the sound of a vise when it sometimes falls
into the keyway slot and you can never tell if some foreign material has
found it's way under the vise. If you have to angle the vise the key
ways are in the way. I rarely use those swivel bases that you can buy
with the vises, they're not accurate at all. If you need to angle the
vise I just use an angle block held in the the vise and clamp the vise
to the table as if it was a part you were holding down and indicate the
on the angle block. You can also use a sine bar to indicate on, laying
flat on the vise ways or in a pinch on top of the vise with the jaws
clamped tightly shut.
--
BottleBob
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Reply to
Bill Schwab
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Karl,
Understood and thanks. Actually, I am starting to suspect that new bolts are simply not adequate. I do not have these problems with the clamping kit, which I used extensively just yesterday.
Is there a particular bolt and/or finish type I should get?
Bill
Reply to
Bill Schwab
Bill Schwab wrote in news:2G0gf.3195$ snipped-for-privacy@newsread3.news.atl.earthlink.net:
If you use Grade 5 bolts (normal hardware store stuff), they will stretch considerably. Use Grade 8 or Class 12.9 (metric) bolts. I would also suggest thick hardened washers. Deformation of the washer will cause inadvertent movement while tightening.
On our Deckel, since the Kurt vice is made for a 'standard' t-slot pattern, it is only possible to get 2 bolts in the vice. The bolts are placed in the inside slots at the front end of the vice and clamps are used at the tail (handle) end.
Reply to
Anthony

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