On 2014-03-26, Jim Wilkins wrote:
"Cydrome Leader" wrote in message
...

Well, it turns out there is an alignment issue. The
tailstock/spindle are
at slightly different heights. Not sure how or when this happened.
I'll
have to figure this out and then try and see what happens.

They may also shift alignment slightly when under a load.

Is the tailstock lower or higher? And by how much?

I understand that some good machines are made with tailstocks
about a half-mil (0.0005") higher than the spindle, so as the tailstock
wears over the years, it gets better before it gets as bad as when it
was new. And that much offset is normally not a problem.

If the tailstock is lower, and if it is a split tailstock (ram
holding part is separate from the base which slides on the bed), then
you can take it apart and add the proper thickness of shim stock between
them before re-assembling -- and then taking care to get the tailstock
horizontal offset correct again.

In a turret, there are reamer holders which will offset slightly
in all directions, so you can get it truly on center.

Enjoy,
DoN.

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