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Machining plastics

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andyf:
Eric, I've machined a crude lens from acrylic (trade names Perspex etc over here; Lucite etc on your side of the pond). As others have said, sharp tools and moderate speeds - though it doesn't exactly melt, it can get a bit "gummy" with friction.

To make the lens, I turned a conical shape, rounded it with a file, then used progressively finer emery paper, metal polish and finally toothpaste for a final polish.  

If you need to stick bits of Perpex/Lucite together and can get hold of some ether (as in bygone anaesthetics), that will give a nice clear joint. Good ventilation prevents you sleeping on the job.

Andy

Swarfing:
If it helps i just machined up some fibreglass block as an adapter for my chuck. The speed i used was on about 75-100 rpm. This stops the cutter from getting hot and i cut it dry. Suspending the item you want clear again in some acetone works with some plastics. Worth testing a bit first? I just oiled my fibreglass afterwards with wd40.

rowbare:
If you are going to machine acrylic, try to find cast acrylic. It machines much better than extruded. ref: http://www.cnczone.com/forums/glass_plastic_stone/22982-melting_acrylic.html

Also acrylic and polycarbonate can be chemically polished: http://bbs.homeshopmachinist.net/showthread.php?t=34730

bob

fixerup:
Greetings,
It machines quite well,  when drilling, I like to put a small radius on my tool to prevent the tool bit to grab and lift the part. Also when I'm cutting close to an edge I try to slow down my feed to not break that edge.  I've use a hand soap and water solution to machine and tapping operation  (1part soap 20 part water). 
Cheers!
Phil

Brass_Machine:
Hi guys...

Thanks for the advice. I got some acrylic rod and made a prototype of the part. Came out quite nice! I haven't done much as far as polishing it up, but I did clean it up a bit. Will try the torch trick to see how that goes...


Eric

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