On Sat, 14 Mar 2009 06:03:38 -0700 (PDT), Jim Wilkins
wrote:

On Mar 13, 9:35*pm, "Terry Coombs" wrote:
Michael Koblic wrote:
...
Mine tilts back about 0.008" in 3". I have done nothing about it for
fear that I will make things worse.

You could remove the column and measure the connecting surfaces to see
which one is off. An indicator mounted in the chuck ought to read a
constant value against the column while you extend the quill.

To measure squareness of the base attachment surface, attach a fixed
horizontal rod near the lower 1x2 edge of a 1-2-3 block and an
indicator near the upper edge, parallel with the rod. The block needs
to sit flat on either 1x2" end, perhaps raised on a parallel.

If you pushed the block up against a square inside corner so both the
rod and the indicator make contact and zero the indicator, then flip
the block over, the indicator will still read zero.

Do that to a corner which isn't quite square and the indicator will
show (+) the error one way, (-) the error the other, or twice the
total.

You don't have to use a 1-2-3 block, all that's necessary is that the
top and bottom are parallel. You could machine a block and check
parallelism with the indicator.

Jim Wilkins
------------
And then there is the easy way.

Use your indicator and a holder. While not as eligant as a
"storebought" one you can make your own out of a piece of
keystock and a bolt. For maximum indicator travel make as long
as possible that will still get the indicator on the table when
in the front and back positions with spindle centered on table.

Measure the front to back squareness. Disassemble the column
from the machine. Put a piece of aluminum foil where the column
bolts to the bed at either the top or the bottom, and
re-assemble. Remeasure the f/b squareness. If it got worse,
move the aluminum foil from the bottom to the top or the top to
the bottom. reassemble and check. If still not close enough, add
another piece of aluminum foil. [be sure these are flat with no
wrinkles of folds] If over corrected, replace the aluminum foil
with something thinner.


Unka' George [George McDuffee]
-------------------------------------------
He that will not apply new remedies,
must expect new evils:
for Time is the greatest innovator: and
if Time, of course, alter things to the worse,
and wisdom and counsel shall not alter them to the better,
what shall be the end?

Francis Bacon (1561-1626), English philosopher, essayist, statesman.
Essays, "Of Innovations" (1597-1625).