"Bill Schwab" wrote in message
ink.net...
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.

When you dial a tilting head, the 90 degree interval is important. I
understand that your bolts are not equally spread, which I gathered when you
gave the dimensions. No big deal----treat each bolt as a critical
position----because that's where you'll place your shims.



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.

See above. Truth be known, if the machine is right, it doesn't matter
because the reading should be 0 regardless of location. The point of
checking location as noted is strictly so you know how much shim at that
particular position. Otherwise it makes no difference, not as long as you
can relate the readings to a position.



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.

It shouldn't make any difference if you move the table, or not, because it
should move without up or down change, at least in theory.

What I do is set the spindle such that it's not centered over one of the T
slots, at which time I have contact at the proper places. You need not be
in the center of the table. It's assumed that the table is flat and uniform,
so you should be able to dial it anywhere, so long as you can make contact
with your indicator as required. For me, that's at 3, 6,9,12. For you, in
this instance, it would be relative to your bolt locations. As long as you
swing a circle that is similar to your bolt pattern, and make contact at the
same positions on the table as you have bolt locations, you've done all that
is necessary.

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

Yep! There's no guarantee that there's not something between the two
surfaces. Clean them well and deburr if necessary. Could be you'll have to
lift the entire head and column assembly, but maybe not. It makes no sense
to go to a lot of trouble to square the column when it's subject to change.
Regardless of the degree of error, if you get down to clean surfaces, you'll
have something concrete with which to work. Screwing around with it if
it's dirty, or has some dings, can be very frustrating. Every time you make
a change, it comes out differently than you expect. You end up wasting too
much time chasing it.


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.

I usually don't worry much about zeroing an indicator, but when I do, I also
adjust it then set it by (in my case) raising the knee. It's far more
precise. Assuming I don't zero the indicator, I make a mental note of
where the finger points and go accordingly. It's all a matter of your
personal work habits. Establishing zero helps avoid errors.

Start out with minimum contact and adjust as necessary. I don't expect
you're going to find a huge discrepancy, and with luck it won't be. I'm
thinking only a thou or two, so you should be able to pick any spot and
preload a couple thou and have it work. No big deal if you have to add a
couple more thou.


Not that I intend to buy one ASAP, but are the name brand indicators
that much better than the imports?

I'm not familiar with any of the imports (aside from the B&S BestTest, which
is/was Swiss made, and is amongst the best on the market), so I hesitate to
comment. One thing I will comment on is the Starrett Last Word. If you
don't have one, don't buy one. While the vast majority of my tools are
Starrett, including one of the Last Word indicators, I do not recommend it
to anyone for anything. The design sucks, and always has. They're quite
insensitive, generally performing very poorly under a thou. There are far
better indicators on the market. By sharp contrast, I have several of
their long travel indicators and recommend them highly.

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.

Thanks!

Bill

Welcome!

Harold