I've seen this route taken so mant times all with same negative outcome and To be honest Other than for the learning experience your just going to burn money messing around like this and again being honest the learning experience isn't really relative to using a CNC machine or getting one running has modern drives are simple to setup and very cheap for low spec drives which will still be far more advanced than anything you'll make.

Far easier and cheaper to just save up and buy the real thing.!!