Originally Posted by
louieatienza
Provided your LM rails have 4 sets of races you can pretty much mount them any way you like.
As to screws, depends on how big the machine is and what you're doing with it. Smaller machine, under 2' X 3", I'd say go with the 5mm pitch and use the smaller steppers. Larger machine, use the 10mm pitch and go with the larger steppers.
I personally feel if you don't need more than 200-250ipm rapids then the 5mm pitch should be fine. Because of the efficiency of the ballscrew, they're easier to back-drive as opposed to ACME. Meaning, for coarse-pitch ballscrews, you may need a larger stepper than you think to prevent any "jolting" forces from causing the stepper to lose position. However with a larger machine, having a higher rapids speed may be desirable, and if you use the 5mm pitch, whip becomes a problem unless you move to the next size diameter screw - which complicates things a bit because now a larger stepper may be needed just to overcome the inertia of the screw and give reasonable acceleration. Here, the coarser pitch screw would require less stepper RPM to attain the same rapids speed, thus mitigating whip.