Harold,

The information you are looking for is how much it will take to tilt the
column until it is at right angles to the table-----which would likely best
be checked at the point of the bolts. I get the idea that the bolts you
speak of are not spaced @ 90 degrees, so determine the bolt circle, and
swing the indicator in that arc.

They are not at 90 degrees. It's no big deal but it leads to a question
below.


You want the indicator to make contact on the front and back of the table,
and at each side @ 90 degrees. If you find the T slots are roughly the
same spacing as the circle you must spin (the bolt circle of the base of the
column),

Let's say the bolts, seen from the center of the column, are at 10,2,4,8
o'clock positions. Do you want contact at 9,12,3,6 or 10,2,4,8 (same
directions as the bolts)? I'm assuming the latter, but I might be
missing something.


move the saddle until the circle permits contact of the indicator
when it's on each side of center.

Back to the clock, say I'm at 8 and 10 stubbornly sits over a slot. Is
it ok to move the table to put table surface under the 10 position?
Again, I think it will be ok by 0.1 inch or so. Failing that, I can
scale the radius up a bit to avoid the slots and then scale down the
readings. My hunch is that would be better than moving the table
between readings, but let me know if that's making it harder than necessary.


You shouldn't have to lift the head off the machine.

Understood. I was thinking of the crane as a way to tip the head more
than lift it.


Just break the bolts
loose (don't take them out if possible)and tip the head slightly, so you can
insure everything is clean under the flange, tipping once left and once
right, then tighten the bolts again and check with the indicator.

So you want me to clean up the flange before doing the first
measurement? That makes sense now that I think about it; otherwise
shimming might knock out the grit that was holding the head in place =:0


Hopefully you understand that once you touch the indicator to the table, you
don't move the quill. Lock it so it can't move, then rotate the spindle.

Yes, with a twist. I have found it a lot easier to rotate the zero on
the indicator to about where I want it and then preload by moving the
table rather than trying to fiddle with the indicator dial itself - the
forces required to turn it are big enough to cause trouble. I am
assuming that here I would pick a likely preload, scan once around to
find the corner to use for a reference, move the quill to zero it, and
then start reading.


What you want to see is how much variation there is from dead true, which is
the condition you hope to achieve. Depending on the quality of your
indicator, this can be troublesome. Lots of indicators don't enjoy being
rotated across slots, so if you can make a setup whereby your indicator
trails off instead of approaches the slots sideways, that's the best way to
go. Don't preload the indicator by much, so it doesn't have to move far
before the ball is on the table as it crosses the slots. Rotate by hand,
slowly.

Got it. Make the preload small enough that the tip hits the bevels
rather than falling into the slots.

Not that I intend to buy one ASAP, but are the name brand indicators
that much better than the imports? In addition to the caliper
(mentioned below), I ordered a backup import DTI. I almost managed to
snag it on a step clamp last week and decided that having a second one
on hand would be a good idea. Smashing a $40 indicator would be
annoying; I'd rather not think about taking out a Starrett.


Let us know how it turns out.

Will do. I will probably get some SS shim stock first in the hopes of
getting it all done in one session. Also, I recently ordered a 12 inch
import caliper; having it will help me measure the larger bolt separation.

Thanks!

Bill