CNC 3018 PCB drill bit break

[A_Camera]

I am milling PCB with 0.1 mm 30 degree V bit at 24k rpm. I think that is better than end mills. Anyway, PCB is considerably harder than wood so you need high rpm, good cutter and just right feed rate. Of course, you also need a machine with low vibration and good rigidity. But if you don't have that, then you can try to lower the feedrate. It is a bit of a trial and error, but best is to start slow with the highest rpm you can get, not too shallow cuts, try 0.4 mm since most copper layers are 0.35 mm so that should be good enough. Also, use some sort of waste board between the PCB and the table. I use MDF which is levelled.

Your picture shows that you have other problems too. Did your machine run away uncontrolled?

[Doddy]

For info, I’ve done reasonable isolation routing using 0.3mm dia end mills. Those have a cutter length about three mm and will snap if you look at them wrong. But great cut compared to v cutters, but together with their fragility are wickedly expensive. To OP, dial out all your other problems before entering the world of exotic cutters.

It’s this experience that resulted in the question whether the image of the snapped cutter is an end mill or a PCB drill. The cutter length looks to be too long for a cutter suited to PCB, but your experience may vary