Greetings everyone!

I just recently finished my new CNC machine and I've been having a blast learning as much as I can.

I've started to try my hand at making some Edge-lit signs for some friends. The first few runs were pretty good, but I wanted some more improvement so I bought a few new bits to try.

I decided to pick up the In-Groove Insert System from AmanaTools. Using their feed and speed chart I started engraving one of the signs. The first half of the cut looked amazing. The edges were crisp and I did not have any real issues with melting. Then I noticed that the bit was no longer cutting. I thought that the material thickness might be uneven but it turned out to be a broken tip.

I was cutting with a depth of .0156 using the RCK-360 30 deg bit. It's tip is .005. My RPMs were at 16,000 (my lowest) and my feeds were at 100 ipm.

I used a few of the other bits on different materials without any issues.

Then I used the RCK-362 30 deg bit with a .020 tip. My depth was .0156 at 16,000 RPM with a 120 ipm feed. The tip broke off on that bit too.

Both cuts were on scrap Lexan from Lowes. I'm not afraid to say that I'm at fault, but could someone help explain why this is happening.

The Speed and Feed Chart is found here and the tool info can be found here.

I'd appreciate any assistance.

Thanks