"Michael Koblic" wrote in message
rvecommunications...
Another recent thread got me thinking:

In the near future I shall have to cut a doughnut like structure from 0.5-1.0
mm brass. The outside diameter 114 mm, the hole diameter 57 mm. The cut has to
be a) clean and b) reasonably accurate (within1 mm).

There are number of options:
1) Snips
2) Fret saw
3) Jig saw

The concern is about the final edge appearance with these three. I fear that
even supported the edge is going to get ripped up by the saw (especially the
jig) and there will be some bending with the snips.

I have never used a hole saw and I believe that sizes reasonably close to
those above are available. How good are these things at producing clean edges?

Another option I was wondering about is using a router with a straight 1/4"
cutting bit. I have a very nice small circle jig which allows for increasing
radii by 1/16" and does a really nice job in wood. Has anyone tried this with
brass or aluminium? I am thinking supporting the brass plate on a piece of
wood and having at it.

Finally, thre are these Roto tools for cutting dry wall which come with bits
ostensibly capable of cutting non-ferrous metals. I tried one of these bits in
a Dremel tool cutting kydex freehand but not with great succes due to lack of
control. Some sort of jig would definitely be needed. The advantage is that
the bits are about 1/8" diameter.

My supply of brass is limited and I am trying to make sure that I know what I
am doing rather than using a "try it and see" approach.

--
Michael Koblic,
Campbell River, BC


Get tubes with the right dimensions and turn or grind a knife edge. With the
sheet on a block of hardwood tap the tube through it with a hammer.