Horrible jagged finish ??

I've noticed a very jagged nasty wall finish on my black acrylic parts. The Acrylic was purchased from Amazon awhile back and can't remember it's specs. I'm running an Epilog 40w 24mini, @ 12 speed - 100 power - Frequency 5000 as suggested in the manual. I just found out that Cast acrylic engraves better then it cuts and the complete opposite with extruded acrylic. Are there any tricks, speed & feeds, etc.. that might help the wall finish look better besides sanding it or maybe this is a stepper/servo tuning issue ?


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Is your Mini on a stable table? If there is any wiggle going on while running the engraver, that could enhance the jagged edges.

LOL, I've heard the opposite, that cast cuts better than it engraves. That has also been my experience, I find extruded gets a little more warped/ugly looking.
That said, can you increase your frequency? My epilog manual recommends the maximum Frequency when cutting acrylic.
Good luck!

I've cut very little extruded acrylic so I haven't noticed differences in cutting but I do know for sure that cast engraves better than extruded.

Air assist can affect the edge quality, too much can make striations. A slower cutting speed should help also.

I had someone purchase some really cheap acrylic and it cut terribly. I have been told there is some "re ground" stuff out there, and if you get some it will cause no end of problems. I guess this is where you need a good plastic supplier. The stuff I get from my supplier cuts perfectly. You will know if you get the bad stuff as it takes more power to cut it. I have cut extruded and cast with no problems, its what the plastic is made of that counts. Acrylic make up can vary.

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Originally Posted by Keith Colson

I had someone purchase some really cheap acrylic and it cut terribly. I have been told there is some "re ground" stuff out there, and if you get some it will cause no end of problems. I guess this is where you need a good plastic supplier. The stuff I get from my supplier cuts perfectly. You will know if you get the bad stuff as it takes more power to cut it. I have cut extruded and cast with no problems, its what the plastic is made of that counts. Acrylic make up can vary.

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Yes, that's the same problem I had a few years ago when I bought a batch that was a really good price, but the plain brown wrapper said "made in Malaysia" and it cut just like that. I don't think there's anything you can do, but like me, save it for items not requiring a smooth glossy edge, and buy a known brand.

Your power, speed and frequency are okay to cut the material. Obviously from the finish, the result is not what you want. In this case, you are using black acrylic, this for me is notorious for having a poor finish when cutting and flame polishing. It behaves differently to clear acrylic which is pure. Coloured acrylic has ingredients mixed with it and so behaves slightly different. You will get a better result by reducing your speed, but I would also recommend that you reduce your power at the same time or it will cause the material to warp and sear as it does with flame polishing. The laser is 40w and undoubtedly carries enough power to burn through much thicker layers but I have found with black acrylic the result is not so neat. Take your speed down to 8 and reduce your power to 85%, the laser will still easily cut through it but the edge will have a better finish. A good air assist directly above the cut will help to cool the material and make the bottom drag (striations) less. My experiences have been with cast acrylic and to be honest I haven't seen or used black extruded.