Erik pretended :
On 11/5/13, 10:26 AM, Tim Wescott wrote:
I was going to say "acrylic", but then I realized that maybe I would be
narrowing it down too much.

How hard is it to machine a part out of hard clear plastic and then make
it clear again? Any gotchas? What plastic should one start with? What
question am I failing to ask?

The part will be cylindrically symmetric (i.e., turned on a lathe), about
1.5" diameter, 0.5" tall, and accuracy can be as sloppy as 0.01 in all
directions. But it would need to be "pretty".

Some plastic that is a bit more rugged in impact than acrylic would be
nice (do they make crystal clear Delrin?) but I can't think of anything
like that which would actually work in this case.


I really have no plastics experience, but once saw some guy cleaning up (what
I think was) plexiglass edges with a propane torch.

It was obvious he'd had a lot of experience doing so, as they came out
smooth, transparent and magically perfect like... he said they called it
'flame polishing'

Just did a YouTube search and got a bunch of hits, but on time to watch any
now.

BTW, there is a polymer newsgroup... though the time or two I looked there
was nothing but Crickets chirping there.

Good Luck!

Erik

Flame polishing with a small propane or similar torch is fairly easy.
Practice on a scrap first. It is easy to set the edge on fire.

Polycarbonate (Lexan) is NOT suitable for flame polising it bubbles and
cracks.
Acrylic is best.

--
John G