Plastic on CNC machine?

I have a computer-controlled router used for wood. Is it possible to machine plastic or similar material on my machine? The router has variable-speed control. I think that I saw a thread on this forum about someone using a CNC machine to create a Corvair van from plastic but I couldn't find that thread. This forum can't find threads using "van" as search word.

As long as the rpm is low (and the tool head moves nice and slow) it shouldn't be a problem. I'd use chunks of 2 pack polyurethane resin moulded vaguely to the shape you want first. I'm guessing that the usual kit polystyrene may get too hot and clog (has a lower glass transition temp).

Polyurethane cuts beautifully with milling tools designed for metal (and they don't go blunt too quick either)!

Have a look at my RS60 thread - there are shots of me milling some polyurethane brake drums using a 1mm milling flute - around 300 rpm. I cast round resin shapes inside shaving can caps etc. ready to fit in the mill/lathe chuck.

Good luck and let us know how you get on!:)

Is there a material that is similar to wood so that woodworking tools can be used but has smooth surface like plastic? I wish to make model cars. Where do I buy polyurethane sheets?

Is there a material that is similar to wood so that woodworking tools can be used but has smooth surface like plastic? I wish to make model cars. Where do I buy polyurethane sheets?

You might be better of with a product like Renshape:

http://www.sovereign-publications.com/renshape.htm

Don't know how it behaves with powered wood tools, but can be shaped like wood using hand tools. Problem is; it is only available in big (expensive) chunks and is not easy to find in the USA.

I think some American modellers were getting small supplies as off-cuts from their local art & design colleges...may be worth a try?

A silly question, but why not make the master buck in something like pearwood and then take a rubber mould off it to cast the plastic?

As long as the rpm is low (and the tool head moves nice and slow) it shouldn't be a problem.

Quite the contrary in my experience. I usually machine plastics (delrin, HPDE, acyrlic, ABS, polyurethane) at high RPM (3000+) on full rapid. Any slower and I get crappy surface finish due to melting.

Quite the contrary in my experience. I usually machine plastics (delrin, HPDE, acyrlic, ABS, polyurethane) at high RPM (3000+) on full rapid. Any slower and I get crappy surface finish due to melting.

Yikes...that's a weird one Mike!

I can only guess that the melting is occurring because the cutting tool is getting hot? Try a very slow speed if you haven't done so already, you may find a cooler tool cuts better. I've found the same thing with cutting plastic sheet with a hand saw. Slow is good...get too fast and the blade sticks.

cutting plastic should be no problem with a cnc router. Mike is correct on a vertical or horizontal cnc machine they use coolant so you do run above 3000rpm. You want a very sharp cutting tool... dull tool will make a bad part.

I master parts by cutting corian with a carbide mill at 30,000 rpm. The stuff machines very well, also sands and takes primer easily. Ettore