DIYbanter - View Single Post - Millrite MVI spindle bearing repair

Joseph Gwinn

In article ,
Joseph Gwinn wrote:

In article ,
wrote:

On Wed, 01 Sep 2010 23:40:42 -0400, Joseph Gwinn
wrote:

In article
,
wrote:

On Sep 1, 8:51?am, Joseph Gwinn wrote:
This is a followup to "Millrite MVI spindle bearing repair - first
report" posted on 16 August 2010.

The Millrite is back together, and was improved by the experience,
although the runout is unchanged.

[snip]

Anyway, when I have an adequate way to measure spindle runout, I will
simply try different outer race orientations and keep the best, as
removing and replacing the spindle with bearings is actually fairly
easy.

[snip]

Joe Gwinn

For testing chucks, I've always used selected dowel pins, 1/4" ones
are fairly easy to come by if not really, really long. May not be
good enough if you're trying to reduce runout to fractions of tenths.

Yes, I've done that too, but using drill blanks.

But, now we are trying to measure the spindle runout, not chuck runout.

Joe Gwinn

Not familiar with this machine but assuming it's an Int 40 taper
or similar can you not clock the inside of the taper. One set of
measurements close to the spindle nose should show eccentricity
and out of round. A second carefully centred set further up the
bore should show up residual tilt.

I did consider using the inside taper, but it's R8, so there really isn't
enough
space for a dial test indicator to reach the back cylinder and still be able
to
see the dial. Unless one can get a really long-armed unit, which isn't
impossible.

It's a bit fiddly even with a small sensitive lever type clock.
I use a home brew capacitative sensor which has the business end
on the side at the end of a short length of 1/4" tubing.

Capacitative sensor. Now there's a thought. I certainly can easily build such
a thing, especially the diode-bridge kind with guard ring, and it would have the
advantage of ignoring the surface roughness and dings of an old and well-used
spindle.

I actually already have such a sensor circuit that I built in the 1970s to track
rats. (Yes, rodents, for pharmacological research.) But I have to find the
circuit board.

Another good idea was suggested by Jim B on 2 September 2010 in a posting to the
Burke Mills (Millrite and others) reflector ):

Use Rollie's Dad's Method http://www.neme-s.org/Rollie%27s_Dad%27s_Method.pdf,
originally for aligning lathes, but ought to work for a vertical mill as well.

I'll use some shafting held in a R8 collet, as a collet is simpler and more
repeatable than any reasonable 3-jaw chuck.

Joe Gwinn