Quote Originally Posted by Jonathan View Post
This, in my opinion, suggests that:
Ok obviously miss understanding but either way flimsy or strong it's fact the rails would help support.!

First let me say dont be fooled by the lack of post's, I've been building diy cnc machines both for my self and others for meny years so I know very well all the newbie mistakes and pitfalls I just havent posted on here.

Regards the down side and your thinking you have to move the steppers with the front plate. It makes no differnce rails on rear or front both you can still have the motor static with the right design. Your right thou the difference is negliable.
I have 2 machines a large and small the large machine use's the moving screw,stepper arrangement with nema34 stepper and the smaller machine use's the static stepper,screw with nema23 stepper both work equally well. The only difference or advantage to the moving stepper arrangment is that it use's slightly less material because you dont need the high backplate but again the saving is negliable.

Eh eh now here's my chance to point out or clarify something you said.!!! . . . When using Profiled linear rails it's important you have a datum referance edge but not for helping stopping them move when crashed, the main importantance is for the alignment when installing. The point being that you fasten one rail tightly up against the referance edge using the correct edge of the bearing or rail depending in which orientation you have them ( they do have a right and wrong way).
Then you tighten the opposing or what I call floating rail or bearing losely then slowly move the gantry or table along the rail nipping the bearing or rail as you go along feeling for any tight spots and losening adjusting the floating rail or bearing to eliminate tight spots. . . . Simplezzs.!