Acrylic edges coming out like dime edges? pics attached

New to cnc here. not sure how to get a smooth edge with cast acrylic? My edges are coming out like the edge of a dime? I am using 1/8 one flute upcut bit for plastics. Brand new bit. The edges are not super bad but could be much better.


No, but going to try climb milling next if you think that would help?


The slots look better so at least that level of quality should be achievable.

looks like chatter, do a test with climb and then conventional to get the feel for it… feeds speeds… and especially depth of cut will make all of the difference with acrylic. Remember that going to slow will result in melting the acrylic.

Using 75 for speed and .02 for depth

its going to take some experimenting. did you mod your machine to make it stiffer?

things I would play with, feed rate and speed of spindle, that depth should be fine though. I haven’t done acrylic in a long time and on a different higher end machine however, so hopefully someone else might be able to give better insight.

here are some links and if you use the search button above, you may find better results.

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It’s a bit hard to gauge the size of this bit it could be the bit flexing. Do you have a ¼" bit you can try?

Just today I did a heap of acrylic. 6mm spiral up cut endmill, 3mm doc, 20mm/sec feed. De walt speed “4” (which is fast). Clean crisp edges, no melting, nice spiral chips approx 10mm long (I hate cleaning this stuff, so nice chips that don’t go everywhere are important).
Ymmv of course…

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Using climb milling option helped a lot

This looks like material is heating up melting a bit and then getting dragged under the bit. I use a dremmel to mill pvc on my lathe (it came off my ShapeOKO). I have a similar problem although I am using pvc pipe. I have a lot to cut and have found slow dremel speeds to slow. I use very high cut rates and speeds (the dremel is on fast, I am cutting manually so I don’t really know the feed rate) until my final pass when I take off only enough to get rid of the chatter. I use motor oil as a lube, mostly because I have it and don’t want to to recycle it unused. When I am out I will move to something greener.

My CNC experience is minimal. In 1976 I took a class on building 4x5 view cameras involving lots of acrylic parts. We used very expensive bits and saw blades. Most tools got fitted with air guns facing the the bits (this helped a lot especially with the difficult drilling. We needed smooth bored accurate 3/4" holes in 1.5 inch thick plastic. When possible we lubricated with mineral oil (this would be a mess on an xcarve but it might help). The teacher said something like, ’ to determine optimal cutting speed slow down the feed until you have problems. If no problems then go slow. If there are problems speed up until you have problems, then choose something in the middle. We cut parts with a bandsaw, table saw, drip press and scroll saw successfully.
I recently bought a garbage fly cutter from harbor freight for some 6"+ diameter holes in plywood (I should have used the Xcarve at school, next time). Until I altered it it would burn through the wood even when sharp. The airhose was the thing that made this possible. Either through speed, feed, lube or air you have to keep the material and the bit cool.