On Sat, 05 Mar 2005 09:23:10 -0800, Grant Erwin
wrote:

I want to center drill a large shaft. The shaft is about 24" long and
is from an old machine tool, but the ends were never drilled for centers.
The shaft is too big to pass through my lathe spindle. I can suss out how
to face the shaft off square, lay out and centerpunch a hole as closely
as I can, and I can then chuck one end of the shaft on the last 1/8" of
the jaws and hold the other end in my hand and gently "pick up" the
centerpunch with a center drill in the tailstock chuck. That way would
get me pretty close, but it would not be exact. I could then mount it
on a center in the tailstock and bring up a steady rest and then remove
the tailstock center and using a tiny boring tool, bore the center, but
how do I know the steady rest isn't just a little bit off?

What is the *actual* procedure for this?

Grant
Lotsa good suggestions here. But if you haven't done it yet and have a
stout live center this is the method I use. The shaft needs to be
round and the face fairly square. A good saw cut is adequate. Put the
steady on the ways and clamp it. Put the shaft in the chuck and
tighten some. Adjust the steady by eye so that the shaft is fairly
well centered. Grab a piece of scrap aluminum and put it against the
face of the shaft, while holding it there bring the point of the live
center against the aluminum. Tighten a little and then back off the
steady a bit and use an indicator on the shaft OD to measure runout.
Use a hammer to tap the shaft into true. You may, and probably will,
have to tighten the center against the shaft while doing this. Once
the shaft is running true bring the steady contacts to bear against
the shaft OD. Back off the live center, tighten the chuck well, and
drill it. If you need the center to run truer than .001 bore it after
center drilling. This method takes longer to read than to do.
Eric