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View Full Version : Cutting dibond and acrylic - what works for me



blackhawk
11-07-2012, 08:36 PM
Hello All,

I just wanted to share what has been working for me to cut Dibond and acrylic sheets. I have a local sign guy that makes his own channel letters and I have started doing his cnc work over the past few months. I have a 2006 PRT Alpha with the PC router. Below is what has been working well for me. I am probably conservative on my cutting, but it works and my customer is happy. All of the info below is based on an 1/8" diameter cutter which was requested by my customer to give him tight corners.

Dibond - This stuff cuts very well. I am using an Onsrud 63-762 at 16,000 rpm and 1.5 ips feedrate. I have been cutting up to 6mm thick sheets in a single pass.

Acrylic - I have only cut 3 sheets of acrylic so far. My first try was with the cutter that I mention above for Dibond. I tried cutting 4.5mm thick acrylic in one pass. I made it about 2 minutes before the cutter snapped. My customer is not sure, but I am nearly positive that this is cast acrylic. I bought the Onsrud 63-712 cutter that is specifically for hard plastic. I am cutting .09 inches deep per pass at 16,000 rpm and 1.5 ips feedrate. My edge quality is good. I may be able to cut full depth but I am scared to break another $30 bit right now.

I also tried an Onsrud 56-041 2 flute straight cutter. It is made for hard plastics. The problem for me was that the straight flutes just packed the chips in that narrow 1/8" cut line. The edge finish was about half as good as the 63-712.

Anyway, hopefully this info will help someone else. Please post any experiences that you have had with these materials.

Brady Watson
11-07-2012, 09:31 PM
Acrylic is dense - so be a bit more conservative with your speeds. 1.5 IPS is about the absolute limit on a single flute tool. Your RPM should be closer to 18,000-20,000 at that speed. Try to use the largest diameter tool you can to cut out and do a rough profile in multiple passes with allowance, then go back and clean it all up full depth to give you a nice clean finish.

You want to adjust your VR so that your Slow Corner Speed is between 35-50 to reduce abrupt movement, which in turn will telegraph into your edge quality. Make sure your pinions are fresh, greased and rails are clean. Any little bump will show up.

You may also want to move up to a 2-flute spiral-O, which should give you a better finish and higher throughput.

-B