Harold & Susan Vordos wrote:

You made a very good decision to avoid a form tool for the grooves, which
would have led to nothing but grief on a small machine. Did you find much
chatter in turning such a large diameter?

Yes if I got a bit to aggresive in the cut depth or feed rate. I have
an independent power feed on the long axis (electric dc motor) so I can
vary the feed rate even while cutting. I just increased feed and depth
of cut 'til I got a bit of chatter then backed off a little. Since this
got sorted out very early in the process, no chatter marks appear on the
finished piece.

Ted