On 2010-06-09, pyotr filipivich wrote:
Gunner Asch on Wed, 09 Jun 2010 01:24:41 -0700
typed in rec.crafts.metalworking the following:

[ ... ]

Another issue..is that not all collets have the holes drilled in the
middle G

When you have a spindle nose thats dead nuts...000000+/-
and you put in a gauge pin..and the runout is .004....that means
something is not right. If it were .0001..its still not right.

Some of the imports are pretty good. Some are pretty bad. The biggest
problem with a lot of the collet sets..is that you have a mix of good
and bad ones. And if you dont select the good one..when you turn
it..things dont come out the right size.

So, best bet is in your copious spare time, go through all the
collets, and find out what size they "really" are, as well as how true
they might be?
I wonder how one might "true up" a collet. It would also depend
on whether the bore is undersized _and_ off center. Boring an
undersized one might be a challenge - I keep thinking of honing one
"out" to proper size, and possibly even to dead nuts centered, But
that would take some know how as well as time and equipment.

What I would do is:

1) Put the collet in the lathe spindle.

2) Put pieces of the right size of shim stock in the slots so
it will not close much at all. (You want it to be just a little
oversized when not clamped.)

3) Mount a toolpost grinder on the compound (and put protective
coverings on everything to prevent the grit from damaging
things. Use a diamond to true the stone.

4) Check the runout and diameter as locked on the shims.

5) Grind it out to the desired size (perhaps selected in part by
the runout to be eliminated.

6) Re-mark it to show the actual size which it now fits.

7) Select another to be fixed and go to step one again. (No need
to repeat the protective covering part in (3) above -- just
leave it in place. :-)

Enjoy,
DoN.

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