Quote Originally Posted by EddyCurrent View Post
plus I don't like the ball screw that far back even though I know Jazz said it would not be problem in the real world.
Ah ah I find this hilarious.!! . . . For some reason you don't like the screw at rear but yet your happy with the rear plate extending down below gantry and flapping about seriously weakening and compromising the quality of finish.?

Think about the machine your building not what some spread sheet that somebody who's never probably built a CNC machine predicts is the optimum location, Or from looking at some poorly built machine who's getting less than expected results then blaming there crappy build quality on design style.

Now I'm not saying that rear is best or optimum but Both ways will work equally same and I'd challenge you to spot the difference in quality of finish in 99.9% of cut materials if I built 2 machines in each style. . . My preference for rear mounted screw is poorly for ease of build and neatness with motors/belts etc and with cable management etc so not messing around with floppy bellows and motors sticking out side of machine.

Your insistence on keeping Z axis slim and low is seriously compromising the machine.!! . . . Front or rear screw no matter but this Z axis is wrong.
Lift the bearings and rear plate so they are supported by the gantry other wise the back plate will flex under cutting forces.!