Motion Errors, X drive belt not straight .. things not working as they should :-(

hi having a number of issues with my Cetus MK3 and not having any luck via support emails/tickets etc so hopefully someone maybe about to assist.
Sorry first attempt at the forum, i’ll attempt to put photos up with this, sorry in advance if that goes pear shape :slight_smile:

  1. The machine started off whilst printing throwing Motion Errors in the software and by re-initiazing the printer from the software i could continue on and get the printing done. Only seem to throw these errors on specific layers during the print, once past them it happily printed to the end.
  2. the printer makes a clunking noise whilst laying down the raft, once past that it prints quietly. i’ve calibrated the bed, raised/lowered and nothing seems to change. using PLA and same brand as i have always used without troubles in the past.
  3. last couple of days the layers would shift , the raft would go down and a few layers on top then moves about 15-20mm across and keeps on printing ?
  4. i have also just noticed that the drive belt and stepper motor that moves the bed/plate is not driving straight. the toothed belt is on the edge of the stepper motor gear. if i power off the machine and gently move the bed forward and back the action is not smooth, i push the belt into the centre of the drive gear and the bed action feels smooth but the belt finds its way back to the wrong position. not sure if that has been like that since i purchased (12-18mths ago) or whether its gradually gotten worse over time.

So editing the post, i can move (with power off) the up down (Z axis i guess) smooth and even friction, but both other axis the belts seem to be not straight and feels uneven , almost like its jumping teeth on the belt but the belt is firm. So X and Y dont seem as smooth to move as the Z (up/down) action,

i’m no expert with 3d printing, this is the first machine i owned and been really only doing little projects for me and the kids, not real rocket science here.

when power off and move x or y axis by hand, you will feel resistance as the circuit will generated counter current to resist motor movement. This is designed to prevent Z axis free fall when power off.

Yes Z axis the one that feels consistant with its friction, the X axis are not like this and feel notchy and uneven. if i straighten the belt on the stepper drive gear the X axis feel smoother and better, but the belt makes its way back to position like the photo again and the motion feels poor again. i hope this can be adjusted ?

@phil91 , have your 4 issues been resolved? I can help with issues 2 through 4 if you still need solutions.

Technology Salad


Did you manage to align your belt? If so would you mind sharing how you did it? I have the same issue.

Did you get everything working again? If so, how did you do? I am having a similar issue

Same with me, got the exact same problem… do you have a solution yet?

Hey guys, I’ll craft a picture to show why and how to correct the misalignment… I’ll post within the next few hours.


When I setup my Cetus the first time I noticed the belts were not aligned in the z-axis and the x-axis. Having a precision machine-shop, I milled the ends of all aluminum extrusions so they are square.

The second method to align the belts on the gears is to insert a brass or steel shim. The thickness of the shim depends on how square the extrusion is where the motors are mounted, so there is no magic thickness of shim material.