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Old 07-21-2019, 09:34 PM
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Default Machining Cast Acrylic sheets

My son has bought himself a CNC router and is setting up to make a product for sale. It involves machining cuts and grooves in 1/4" cast acrylic sheets.

He is using a single flute aluminum cutter in the collet and is not happy with the results. Too much melting and the edges are not smooth. He has dropped the rpm from 20K to 3000rpm and is feeding hard and still no joy. He is a bit anal about quality.
I am of the opinion that he needs a special cutter, but as I only machine nylon or delrin, I have no experience with this stuff.
Any advice I could give, he's already been there.
Any advice for the lad?
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Old 07-21-2019, 10:21 PM
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I've had very little to do with acrylic. What I do know is that it's hard, brittle and has a (relatively) low melting point. Perhaps not the best characteristics for cutting with a rotary tool. I do know of a couple local places that cut a lot of it with waterjet and that seems to work out very well. Perhaps it needs a different process to rotary cutting. The place that sells him the material should be able to tell him what the best process is...
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Old 07-21-2019, 10:53 PM
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The main thing he cuts is PVC foam board and his Banggood cutters work fine on that. He says this stuff is designed for rotary cutting and he would have to sand the edge smooth.
I suggested he get the diamond cutters and in the mean time he can farm out the acrylic to a water jet place.
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Old 07-21-2019, 11:15 PM
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Try a HSS router bit, ideally with no rake angle. You can also try flame polishing the edges after machining it and see if that helps.


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Old 07-22-2019, 12:11 AM
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What size is the cutter and depth?

" feeding hard " what is that in ipm.
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Old 07-22-2019, 12:56 AM
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Quote:
Originally Posted by greywynd View Post
Try a HSS router bit, ideally with no rake angle. You can also try flame polishing the edges after machining it and see if that helps.


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+1 what he said
HSS router bits is what we cut the plex and Acrylics for making reptile habitats and saltwater aquariums and terrariums...
and as he mentioned cleared the acrylic with a blue flame torch.

there is a trick spray to keep them from burning the edges it is a silicone spray you spray the glass and bit with before cutting it helps keep the bit cool can be found at most plastic suppliers... been a while since I bought any.
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Old 07-22-2019, 01:03 AM
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Quote:
Originally Posted by LKeithR View Post
I've had very little to do with acrylic. What I do know is that it's hard, brittle and has a (relatively) low melting point. Perhaps not the best characteristics for cutting with a rotary tool. I do know of a couple local places that cut a lot of it with waterjet and that seems to work out very well. Perhaps it needs a different process to rotary cutting. The place that sells him the material should be able to tell him what the best process is...
Kieth, pretty much all the plastics places here still use CNC routers to cut their materials any real thick material is sent out to waterjet but that's material thicker than 3/4" anything thicker is pushing it with even a CNC router...
unless its PVC or corrugated PVC board and foam boards.

but then we used spiral saw bits for some of that to get a clean-cut... with use of a cooling lubricant...
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