In article .com,
wrote:
Gunner...Is the outside edge of your table on your mill higher than the
inside part of the table where the T-slots are? I assume that the table
should be completely flat from edge to edge and end to end. I guess it
is likely that the the inside of the table has "sunk" over the years
because of things being clamped to it. It looks to be from .002-.005
low in places. My plan was to completely check the table end to end and
then draw file it back into shape. Any suggestions? Thanks, Steve

That does not sound right. I can think of at a few other
possible causes of this observable problem. (I'm presuming that you
have swung an indicator mounted on an arm in the spindle over the table
to discover this problem.)

1) It could be that the head is out of tram. At least, most Bridgeports
have provisions for adjusting the orientation of the head to the
table -- both front to back ("nodding" the head) and from end to
end (tilting it to one side or the other). Until this is known
to be right, don't trust measurements made by swinging an
indicator in the spindle.

2) Wear in the Y-axis slide. This may be more worn in the middle
or at the back, depending on usage patterns over the years.
This will take a lot of work to fix, if that is the problem.

3) Wear in the Gibs of the vertical slide, allowing the knee to tilt.

Of course -- you might actually be talking about the borders of
the table, which define the troughs to control coolant flow.

If it is this, I would suggest that unless you need to mount
something on the table with a footprint bigger than the flat area of the
table, you leave it alone.

I guess that this could come from someone using the machine
itself to grind the table flat, and not able to reach the border fully,
so they left it all untouched.

You could make a riser plate for the vise, if that covers more
than the flat area.

Good Luck,
DoN.
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