Re: Setting Lathe or Mill Gibs

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@...> wrote:

>
> kiwiavi wrote:
>
> >Hi Is there a more scientific way to set gibs other than "when it
> >slides freely"
> >

Here are two more "scientific" ways of adjusting your gibs that I
have come across in my travels. I have not tried either, but the
sources were good. Your mileage may vary.

CNC Adjustment
===============

CNC machines make gib adjustment a little more difficult. Without
handwheels, you can't really feel how tight they are. Commercial
CNC machines make the adjustment by measurement how much amperage is
drawn by the motor during traversal. One account I read indicated
it should be about 30% to 50% of the maximum rated amperage for the
motor.

Bridgeport Factory Adjustment
=============================

This is supposedly the factory procedure used by Bridgeport to set
the gibs. Use a 0.0001 reading indicator and measure the slop in
the slide. Example: For the X axis, place the mag base on the end of
the saddle and put the stylus on the table. At that end of the table
push and release. Then pull and release. The differance is the
amount of clearance in the slide. Repeat at the other end of the
saddle. Adjust gib in a like new machine with little wear to give a
reading of 0.0005. A machine with more wear will have to be checked
with the table closer to the end of travel. The same procedure is
used to set the saddle to knee gib. There must be some clearance for
the oil film and that film also helps dampen vibration. On a machine
with hardened and ground box ways and turcite on the moving member
the procedure is to set the clearance to almost nil. 0.0001 is a
good number.

For a mill that isn't as well made or in as good condition as a new
Bridgeport being adjusted by the factory, its hard to say.

Enjoy!

BW