In article , Harold and Susan Vordos says...


"Sprydle" wrote in message
...
snip-----.

My other collet is for brass hex stock - 4.98 mm across flats (0.196
in) which I think equates to 3/16. I have managed to find hex collets
of that size so I think I'm ok there.

Not really. 3/16" is .1875", so the collet would be too small to grip the
stock properly. When you open up a collet that much to grip oversized
stock, it grips at the rear only, often indenting the material because the
gripping surfaces are no longer parallel. It could prove to be a problem
in brass. The other inherent problem is that the material won't
necessarily end up parallel to the spindle due to the very narrow area of
contact. It may not be self aligning. You should try for a collet that is
within +/- .001" of material size if your project is critical.

The best way to make specials like this is to wire EDM a new undersized
collet. If only for a few parts, a soft steel collet can be used, or
a regular 1/16 or whatnot collet can be used to start.

Any shape can be done this way.

Jim


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