thrust bearing

I built my 3d printer based on a variant called the Samuel:

(Except I enlarged it 50%). Anyway I used thrust bearings to carry all that weight pressing down on the z motor. I haven’t builtbmy mpcnc yet but it looks like you do something similar with a 608 bearing correct?

I put the bearing there to help with backlash and kill all the load from the stepper, at least as much as possible.

Yeah I guess you’d have to either have to put a thrust bearing between the bearing and the coupler to carry the weight or you could eliminate the 608 completely but then you would need to redesign slightly to give thrust bearing a grove to sit in.

Did I miss something? Is there a bearing somewhere in the z axis drivetrain? I do have a leftover bearing, but I thought you just sent me one too many. All the bearing mounting places in the rollers and the middle section are accounted for.

Check this pic out


Thanks, mcmasterp! That clears that up. I’ll install this “extra” bearing tomorrow. Might explain my occasional problems with the z axis!

Where did you find that picture?


Its on the thingiverse page. Lots of them to explain how to build

The bearing does not bear any Z weight. It only keeps the horizontal loads off of the stepper. The Stepper bearings and the hex coupler nut carry all the Z weight. Right?


my hope was to not have the steppers bearings or the coupler carry any weight

Wow, those were some helpful pictures. I had never looked at all of the pics on thingiverse. I used the assembly instructions here:, which are really good, but the z axis explanation leaves out some details, like the thrust bearing and the backlash spring.

Thanks for the info.

Don’t feel bad, I also thought I had a spare bearing. I caught it as I was doing the final install of the Z stepper.