Machining plastics with CNC

[Ben Mitchell]

My main concern is the thermal expansion - I've heard that with UHMWP this is a real problem. Is that true?

Lexan I've considered, but is well above my budget.

The heat from this router is my biggest concern - it gets *really* hot in there and the system is designed for small modeling jobs - it simply cannot dissipate the heat a large job like this produces. In the past, I've let the router cool between rough and finishing passes, but it still warped wood. Machining time is roughly 5 hours per square foot. Stepover rates for the roughing pass is 85% and 15% for finishing passes. I could cut down the heat for the finishing cut by upping my stepover but that makes a poorer finish.

UHMWP was my first choice, and I had the phone in my hand to order the materials, but I read an article about it's rate of thermal expansion and decided to ask around.

After machining it will not be under stress, just getting walked on a bit. PVC might be an option but I'm afraid that might melt too much.