Re: setting backlash on a VMC - how



clay wrote:

So does anyone have a establihed procedure for measuring and adjusting
backlash on a Vertical machining center?

Clay:

Here are the relevant parts of a post I made in March of '99.

===================================================================
If your control has a Backlash Setting get a .0001 indicator put it in
a tool holder crank the Z down to the table or some object. With your
handwheel set to tenths, move the head down until your indicator
reads 0, now count the number of notches your handwheel moves before the
indicator moves even one tenth. That number may be 15 for instance.
With Fadals that is the backlash number you put in the BL command.
Recheck it after you've reset the backlash. You may have to do it a few
times to get it right.
If you been getting inconsistent depths, if when you are doing
tool
length offsets the Z seems to move AFTER you've stopped the handwheel,
if you can move the handwheel without seeing a tenth immediately
recorded on the readout, if any of these things are happening them maybe
you need to set the backlash in Z.
A sure way of telling if you need to set the backlash in X or Y
is to
mill bore a large hole then run an indicator around the hole paying
special attention to the four quadrants. If the indicator jumps .001 or
more in the quadrants you may be way overdue for a backlash resetting.
Fadals have backlash setting for center, left, and right ends of X table
travel also center, near and far in Y table travel.
I'm not speaking to the experienced users here but the people
that may
not have realized that they CAN reset their backlash themselves without
calling for a maintenance tech.
===================================================================

Now that was mainly for setting Z backlash, but you'd go about
adjusting the X and Y backlash setting essentially the same way. You
have to look in your manual for the particular parameters to set.


--
BottleBob
http://home.earthlink.net/~bottlbob
.

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