Some CNC machines, like the Bantam Tools "Othermill", have software that does a "test" and will tell you if you'll crash into the board, and can recommend drill

Some CNC machines, like the Bantam Tools "Othermill", have software that does a "test" and will tell you if you'll crash into the board, and can recommend drill bit sizes. I'd highly recommend this machine btw, excellent support and I've been very happy with the results for both wood and PCBs.