im planning my first cnc build at the moment. its on a budget so ive decided to use graphite impregnated nylon as slide bearings. its difficult to shows what ive got planned using words but would like some feedback on this idea. ive also got a question regarding software (jumping ahead of myself i know) but i was wondering is there calibration for example how will the router know how far down to go without hitting the bed and also things like cutter diameter and cutter changes for different sized cuts (does it ask for a change during a cycle?) these are just some questions that popped into my head.

thanks in advance