Need advice on strength in these 2 set-ups

[Stevie]

First image is looking down on the 2 NSK slides for the Z axis (slides are blue); here they are 135deg spaced; the loads for the cutting forces are on the NSK slide assembly; X and Y axis forces are shared with both slides however the left-most slide is angled to maximize the forces through the slide when a Y axis cut is taken; the other slide is to maximize the X axis cut; as an after thought I redesigned the set-up as below; both sets of axis will see the same forces for both axis cuts
I'm thinking the top set-up will be harder to make; while the lower might not be harder to make the ballnut assembly will take a bit more shoehorning to make it all fit (note slide for the rails are not drawn as I'm still collecting pricing and the designs of the sliders are not the same make for make; the 15mm wide rails are very similar)



So how many of you design type guys want to estimate the best loading situation

[HuFlungDung]

Stevie,

I think its commendable that you have considered the slide placements in terms of reaction to X or Y movments.

How many "trucks" are you using per slide? Is it really your plan to have the slides sticking up that much without supporting "backbone" behind them?

[TAB]

Nice layout. You might want to move the ballscrew to the center to better distribute the foce to both rails otherwise a moment arm might be created which could induce a vibration particualrly at high traverse speeds.

If this for light duty machine (ie. for wood and plastic) I think it is good. This setup would probably work even for aluminum.
As for loading and forces, I would suggest that there will not be a lot of force applied to the z axis. The biggest forces will be from the movement and forecs of the weight of the ram as it moves around. If there are any large forces the cutter will break unless you are planning on cutting steel or alloys where there is alway forces on the ram while cutting. You mentioned that you had THK rails and if you preload them properly the configuration should be less important.

[Stevie]

There will be 2 per rail; the spindle carrier is red; it is a 500mm long tube with the slides bolted to machined pads; with 1/4" walls of steel or alum; I think the slides will not be going anywere unwanted

TAB; the ball screw is center in the upper arrangement; it just looks offset due to the angle of the screen shot; it is off center to the backsupport; but centered to the force vectors