In article ,
John B. Slocomb wrote:

On Mon, 29 Mar 2010 00:02:04 -0400, Joseph Gwinn
wrote:

In article ,
John B. Slocomb wrote:

On Sun, 28 Mar 2010 20:12:33 -0400, Joseph Gwinn
wrote:

On my old (built in 1965) Millrite MVI vertical mill, one annoyance is the
difficulty setting the table to a specified X (side-to-side) location.
One would overshoot, in both directions. My first theory was that this was
....
[big snip]


The usual procedure is to make all final adjustments from one
direction which negates any looseness in fit between the lead screw
and the nut. Most old guys do it without thinking - back it off a half
turn too far and go back 'till you get where you want to be for the
next cut.

Yep. Though I'm still trying to achieve true old-guy machinist status. I
had come to the go-one-way solution, but cutting in one direction but not the
other (even with the X-axis clamped) still caught my attention.

I apparently didn't read about cutting in one direction but if that
happens there must be some play somewhere. Climb milling will
certainly pull the work into the cutter but that is usually obvious
when it happens and of course, if there is play somewhere, the
opposite cutter rotation will push the work out of the way.

Yes, there was play. Two things were wrong.

First, the saddle-knee gib needed to be tightened. This solved the
cut-in-one-direction problem. As it happened, it was climb that didn't make
contact, but climb-versus-conventional was not the issue - the problem was due
to the table cocking one way then the other way. Self-feeding was not the
problem, for lack of contact.

Then, the thrust bearings at the left end of the table were cleaned, greased,
installed, and preloaded. This greatly reduced the difficulty in setting the
table to a specified X-location on the DRO.

Next will be to tighten the table-saddle gib, but this is a big deal (as removal
of the table-saddle assembly is required) and so it may be a while.

Joe Gwinn