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Re: Making Flat secondaries - disaster #1...



Original poster: "Metlicka Marc by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>



> 
> ...And adding my $0.15, don't blast your way thru a large hole in
> a single shot. For even a 1/4 inch hole, especially in plastic,
> start with an 1/8 inch drill. Drilling in steps becomes very important as the
> size of the hole gets larger. A 1/2 inch drill has a lot of momentum and
> messy things happen.

I have to disagree with this, Trying to drill a 1\2" hole that is pre
drilled will definitely grab into the part!
  A real good bet when drilling acrylic and lexan is to grind your bit
into a very wide included angle, the included angle should be around 160
deg. so that it chips away at the material, not cutting into it.
Also, I have found that straight mineral oil used as a lube on jig saw
blades, or drill press bits and hand tools will allow a good clean cut
with little cleanup.
 drilling acrylic is much like drilling cast iron, (except for the
melting at high cutting speeds) If slightly less then flat cutting
angles are used it will peel the material out of the hole very nicely
with mineral oil as a lube.
Hope this helps,
Marc M.


> 
> Cheers,
> Ralph Zekelman