I am in the process of designing and building a CNC router for hobby use only. It will be a custom 4' x 4' cross between the CNCRP and the KRMx02 design using NEMA23 380oz/in motors from either CNCRP or Automation Technologies. I am trying to come up with a custom built R&P drive similar the CNCRP PRO drive but with some improvements in an attempt to add some rigidity to the design. My thoughts were to use a larger 40T 2"P.D. pinion for more tooth contact supported by two radial ball bearings for more rigidity. The drive pulleys & belts will be either 9mm or 15mm wide GT 3mm. The two combinations that seem to work would be an 18T & 100T 5.56:1 ratio which would give you 1.131" travel per rotation of the motor which is close to the CNCRP design or a 18T & 120T 6.67:1 ratio which would give you .942" travel per motor rotation. I will also have two ball bearings in the pivot to minimize lash. My question is, are there any problems that I am missing with my design and are the improvements worth the effort of making a custom design verses purchasing prebuilt.