On Sat, 16 Jul 2005 13:00:07 -0700, Grant Erwin
wrote:

I have a need for some 4" circles of 1/8" steel. They have to be pretty flat.
They will wind up with a central hole of 5/8". (Tolerance here is about 1/32",
not really machinist tolerances.) If I could think of a clever way to hold them
by the 5/8" hole really solidly, I might be tempted to try grinding up a
trepanning bit - how hard can it be?

I suppose I could try cutting them with a circle template and a plasma cutter,
or I could make up a bandsaw circle jig and try cutting them on the bandsaw
(don't have a 24tpi blade though) or even borrow someone's hole saw and try
banging them out in one go on the mill. I don't have access to a blanking press.
I only need 3, so it isn't worth having them laser cut.

I have a few days before I need them. What's the easiest way to cut these?

Grant Erwin
Kirkland, Washington
Lessee Grant, you have a plasma cutter and a lathe. Rough cut the
steel with the plasma cutter. Then put in your 5/8 hole accurately.
Then chuck a 5/8 dowell pin in the lathe leaving .350 sticking out.
Slide the plates on it. Use a live center to press a plate against
your stack of plates that you slid onto the dowell pin. Turn to size.
You need a pretty good live center for this. But pressure turning
works well and is fast to setup. Take light cuts so the plates don't
catch. I used to do a repeat job on an 18" swing lathe where I would
stack up 20 each of 1/4 aluminum rough cut plates. These plates did
not have through holes in the center. I just pressed them against the
chuck jaws with a live center to hold them for turning.
ERS