srp
Well-Known Member
Lengthy thread on Acrylic yesterday, which I started to reply to but couldn't post (because Tiscali are so useless).
I found a link to a really useful pdf file on all aspects of machining perspex here - http://www.bayplastics.co.uk/Perspex%20-%20Workshop%20Handbook.pdf
Two points which didn't come out of the original thread:
1. There are 2 types - Cast and Extruded. Extruded is the sort you can buy at B&Q. It's much more prone to overheating than the cast variety, to the extent that we can't use it on our CNC machine. It also suffers from stress cracking on cut and heated edges.
2. Feed rate is far more critical than cutter speed in terms of overheating and melting problems. All our machining is done with high cutter speeds (certainly as high as when machining mild steel) but with very low feed rates on auto machines, and low feed pressures with non-auto machines (eg bandsaws and circular saws). If you use low cutter speeds the material tends to chip badly - particularly so when drilling and turning.
I found a link to a really useful pdf file on all aspects of machining perspex here - http://www.bayplastics.co.uk/Perspex%20-%20Workshop%20Handbook.pdf
Two points which didn't come out of the original thread:
1. There are 2 types - Cast and Extruded. Extruded is the sort you can buy at B&Q. It's much more prone to overheating than the cast variety, to the extent that we can't use it on our CNC machine. It also suffers from stress cracking on cut and heated edges.
2. Feed rate is far more critical than cutter speed in terms of overheating and melting problems. All our machining is done with high cutter speeds (certainly as high as when machining mild steel) but with very low feed rates on auto machines, and low feed pressures with non-auto machines (eg bandsaws and circular saws). If you use low cutter speeds the material tends to chip badly - particularly so when drilling and turning.