Joy Hought on sat 15 aug 98
Plastic is not inert. Actually, all plastic outgases to some degree, just
by sitting there. This doesn't pose a problem for most people but there is
a documented fraction of the population (admittedly very small) that are
sensitive to these "fumes", whether it's being melted, cut, bent, or just
looked at; and the jury is still out on the longterm effects of plastics
on the rest of us. This isn't alarmist, this is fact. In general, the
more flexible the plastic, the greater its tendency to outgas, so very
dense plexiglas or similar materials are much "safer" than, say, the ziploc
bag that holds your sandwich. (scary, eh?) BTW plastic + kinetic energy
= heat (can you say friction?), which can indeed free up gases, so just
wear a decent mask and make sure the area is well ventilated (as with any
other ceramic material), and try not to get chunks in your eye, because
that'd hurt.
Joy in Irvine
Diana Pancioli on tue 8 nov 05
Good Morning Kelly:
Please don't give up on plastic.
It works and it is a lot easier than cutting metal.
You saw the 50+ dies that I brought to the workshop.
I had no trouble cutting them,
they are all 1/4 inch thick,
and many are quite old now.
I have NEVER had a die break.
Polycarbonates are not all the same.
I have had a few pieces that cut as you describe:
cut and melt back together as they go.
I am still not sure what causes it.
I know an old dull blade exacerbates the problem.
I wonder if the age of the material has anything to do with it?
Not understanding plastic chemistry, I can only guess.
I do know that occasionally I run into a piece that
doesn't seem structurally uniform throughout.
I'll be cutting along fine on a straight line
and suddenly hit a hard spot.
I am guessing that somebody didn't stir the molten plastic well enough.
Also, I think brands may differ. Lately, I haven't bought Lexan,
just because it wasn't available, although that was all I used at first.
Perhaps polycarbonate formulae vary from one company to another?
The stuff is bullet proof, it has lots of crosswise strength,
so 1/4 inch is plenty, but does need to be reinforced with a U bolt
at critical points if you cut certain shapes.
U bolts are very easy fixes for complex or hollow shapes,
drill holes, screw it/them on and you are ready to go.
My scroll saw is cheap, maybe that makes it better?
It doesn't have much speed. When I have occasionally
had the trouble you describe, especially in funky corners,
I cut into them in small pieces, biting off little bits of the shape
with each cut, like cutting a pie.
If you can't find a solution for your problem,
and many good ones have been offered on the list,
(I'd try oiling it) I will send you some plastic that
works here, and then we can see if it also works
with your saw.
Diana
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