On Tue, 14 Dec 2010 09:55:04 GMT, "Harold & Susan Vordos"
wrote:


wrote in message
.. .
snip-

Roger Shoaf suggested something essentially identical. I can see the
benefit of doing the ID first even using pre-fabricated blanks as I
do. I am still confused as to the benefit of a mandrel vs. 3-jaw
chuck.

It's pretty simple. Any time you can avoid using a mandrel, you're likely
better off. That would be especially true when attemting to turn what is,
essentially, a large, thin washer. Chatter is an ongoing problem,

You said it! The piece I described certainly does that. I have got rid
of the chatter by putting a spacer behind it.


driving the part without slippage. By preparing the OD of the part first,
easily accomplished by pressing the part against a plug, using a plate with
a live center. Once the OD is machined, the part can then be chucked in
soft jaws and faced, bored and reversed with no issues. Best of all,
chucking the OD pretty much eliminates chatter, especially if the part nests
on a proper cavity. Soft jaws solve all the problems of holding large
diameter thin pieces.

I see your point, too. OTOH you gotta love the diversity of opinions
on this group :-)

Michael Koblic,
Campbell River, BC