Any tips for milling acrylics?

Any tips for milling acrylics? I’m just looking at 2.5mm acrylic and need to be able to mill dimensions, cutouts and some minor engraving.

Previous attempts have been disastrous. Some hints as to what end-mill, feed rate etc would be very useful. I’ve got a new aircompressor which I may be able to hook up as a coolant.

I don’t have a co2 laser so can’t go that route. And I believe normal cheap lasers are insufficient to cut 2.5mm acrylic.

Tia
Justin

Use single flute end-mill only, not too aggressive feedrate. I tried milling only with extruded acrylic (feedrate 4-6krpm and 3-5mm/sec) and even with these very conservative parameters I got it melting in the middle of a job. Possibly air cooling is not sufficient, some people are using water old alcohol (I see fire risk here) mist for better heat dissipation.

Thanks. What diameter end-mill do you use for fine jobs? I.e. cutting a 1010 square out of a piece. Or cutting perhaps 10080 dimensions. Are small mills (1mm) too weak for acrylic? Or perhaps can’t eject the chips quickly enough to stop seizing.

Small diameter cause melting easier. My best results were with 3mm and 4mm. This might be too much for very small parts, but should work fine for 100x80 size.

I’m waiting for new exhaust fan for my laser and as soon as it arrives, I will be able to laser cut acrylic for your project.

That’s very kind Sebastian!

I found that faster feed rates helped not have melting and I reduced the depth of cut. I have also had success with fusion 360 adaptive tool paths so I could take a full depth of cut but you end up milling a lot of extra acrylic so I prefer small depth of cut. I also only use end Mills I’ve never used on aluminum do they’re super sharp. I also end up stopping jobs a lot to crack off melted acrylic which is why feed hold and resume is so important to me without losing position. See my YouTube video on “fixing messed up jobs” to see my technique for melted acrylic. My last job I melted the acrylic like 20 times but still completed it fine.

has anyone tried adapting the job so that, say, every 20 seconds the mill lifts off the material to allow both to cool? (although there is still the air-friction on the end-mill of course)

I think blowing high pressure focused air is key. I doubt lifting the end Mill helps