A plasma torch will cut to that accuracy. Make yourself a washer template
and burn the center hole first. If your edge distance on the torch is say
half inch your center hole on the template would be 1 5/8 and your outside
diameter would be three inches. My first inclination is to hole the
template with a magnet but it may give problems with the plasma cut.
You also could make yourself up a radius cutting attachment to clamp to
your plasma torch much like people use with a oxy acetylene torch.
Randy


"Grant Erwin" wrote in message
...
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