This is my first build that I am creating from an old Helava photo negative scanner. it already had everything I needed for the X/Y axis' as far as rails and pillow blocks and a good foundation. The motor drives only had a movement of about 4 inches each direction. I fabricated a gantry from the aluminum plates they used to move the negative around with. I want to do a dual purpose machine for artwork so .001 tolerances are not really my concern. I will be using a rotozip or dremel for a routing spindle but my dad would like to do plasma. I have considered a belt type rack and pinion vs a dual acme lead screw for the X and the same for the Y but with a single acme. my travels are only in the 22" range so im not concerned about lead whip or anything just complexity of the design. Also in the case of a lead screw would you consider center drilling the lead screw and attaching directly to the motor? or would a bearing on each end with a motor coupler be in good design? and finally how would I determine the motor force required to move this thing?! thanks in advance!