Hello. So I know nothing about CNC machines. However I am looking to buy a cheap CNC machine. My problem is that most of the cheap ones say they don't cut hard surfaces. I need to be able to engrave quartz. I already engrave wood with pyrography and Im expanding my work. I see that I can buy diamond coated drills. Am I right that I can just by a cheap machine and a diamond drill tip, and fit it to the cheap machine then Im good to go? Or are there complications? Would I need a more expensive machine? Thank you for your help.