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Doug White

wrote in news:99100af4-0eac-4317-a37e-432a8b18f153
@f18g2000yqd.googlegroups.com:

On Apr 7, 8:16*pm, Doug White wrote:
I need to make some clear front sight apertures for my target rifle. *
These have a conical hole bored in the center, which makes a small
black
ring when mounted in a hooded sight tube. *The commercial ones are
getting scarce, especially in the sizes I need. *The OD is ~ 0.86",
and
the inner hole will go down as small as 0.095"

I'd like to turn the OD on a short stack of blanks bolted to an arbor
with a 2-56 screw. *If I can cut them into rough octagons, I should be
able to turn them to size fairly easily. *What I'm wondering about is
t
he
best way to cut out the rough blanks without raising a burr or making
a
mess out of the protective plastic/paper film on the back side. *I'd
planned on using my bandsaw, but my experience is that the back of
plastic cut on it is pretty rough.

I was thinking I could back up the plastic with scrap masonite to get
a
cleaner cut. *It might also be time to put a new blade on the saw. *I
thought about sticking the plastic down with double stick, but I
suspect
the protective film would come off when I try to remove the backer.

Any other tricks or suggestions?

Thanks!

Doug White

This came up once before, my advice is the same, make a punch and die,
should work well with thin stock. Undoubtedly the way the commercial
ones are made. Wouldn't take long to bore an oblong block of steel,
then slot it, die block and punch guide all in one. If you need a
concentric hole, a simple jig with a bushing would let you drill a
centered pilot hole, then open it up with a clock reamer to whatever
you want. A Sat. afternoon project. Most likely the originals were
from acetate sheet which punches better.

They are made from 3mm thick aircraft window grade acrylic. Making a
punch (assuming it didn't just shatter the things) is probably a lot more
effort than making a half dozen or so by hand on the lathe.

Doug White