Give me a starting point with acrylic sheets

[windcrest77]

Hi

I've used my Iconic for wood and aluminum sheet a lot. Now I need to profile and mill clear acrylic sheet, 3/16 thick, using a 1/8 bit preferably upcut. Can someone who does plastic regularly please give me a place to start on the following?:

1. What's a good bit model to buy?
2. What's a good speed?
3. What's a good feed rate? (conservative not in a hurry)
4. What's a good depth per pass? or can I do 3/16 in one pass ideally.

I can adjust, but I figure I'd save myself some wasted pieces by looking for a fellow CNC'er that has more experience with plastic, because I'm a plastic-milling virgin.

Thanks!
Rick

[dadealeus]

Hi Rick,

I've cut a bit of plastic. The challenge is making sure the material stays cool enough so that it doesn't begin to melt or deform.

As always, a good rule of thumb is the less flutes you have on your endmill, the less heat will build up. I've had good luck with the same single-flute endmill I used for cutting aluminum. Something like this will work well and is pretty cheap:

www.amazon.com/SpeTool-Aluminum-Carbide-Cutting-Acrylic/dp/B083TKN62R/ref=sr_1_2?dchild=1&keywords=single+flute+spiral&qid=1633810206&sr=8-2

I'm not super familiar with the Iconic line (I have an AR8 Pro), but I have a tough time believing your machine couldn't easily hit 3/16 in a single pass.

For feeds and speeds, I recommend GWizard. It has a free trial and will give you some good feed/speed data for most materials. If you use your machine often, GWizard (or another software like it) is absolutely worth the price.

Plugging in some quick values for the 1/4" endmill I just linked, you can give the following settings a try:

RPM: 20000
Feed: 51 ipm
Depth of Cut: .375"
Cut Width .25"

You may need to fine-tune it, but that should get you started.


Hope that helps!

[dadealeus]

If you want something a little more conservative, you can try:

RPM: 16000
Feed: 17 ipm

Same depth and width of cut as above.

[windcrest77]

Thanks! I have plenty of 45 degree helix single flute bits for aluminum already, so I'll try that. Not having done acrylic I probably would have just tried a 3 flute 30 degree wood bit first time, which would surely have clogged on melted plastic. Then I would have tried a 2 fluter 30 degree, probably better but still might melt it. So it was worth asking, you probably saved me some issues. Makes sense.

I wish this forum had a section entirely dedicated to materials and their various bits/speeds/feeds/depths discussion, I didn't know where to post.

[dadealeus]

Sure thing. You can likely get away with a 2 flute without any issues as long as you have good chip clearing (dust collection or compressed air) to keep the chips from being re-cut. I've cut plenty of hard plastics with a 2 flute straight cut endmill without any issues as long as the chips were removed quickly. A single-flute just gives a lot more room for error.

One of the first times I cut plastic I sheared a 1/4" 4-flute upcut endmill clean off when the hard plastic melted in a tight corner and then re-solidified around the cutter as soon as it tried to move away.

Single-flute just gives a lot of room for error and, in plastics, the cut quality is more than adequate for my needs. However, if you find the cuts a bit too rough, give a 2-flute a try - but I wouldn't go anything higher than that unless you're just doing a finishing pass and removing a small amount of material.

[jaciro]

Some years ago, I had a project, and I needed a relatively big amount of acrylic paper. I used this website, and you may check them too acrylic sheet china. The papers are made in China, but their quality is one of the best. On top of that, I looked for some models, and they had the best rapport when we spoke about price and quality. I think this could be a good starting point for you. Even discussing details about the contract with them is easy; go on the "contact us" page on their website, and I'm sure you'll find a solution.