AnyCubic Chiron shifting in Y axis


I have an AnyCubic Chiron, and sometimes the bed doesn't move correctly. This causes the prints to shift and ruins the print.

I've spent a lot of time watching it, and noticed that when this happens, the belt stops moving for a short period of time, and then a "thunk" and it continues printing, with the slight from when the bed wasn't moving.

I've captured a video that demonstrates this. You can see it get stuck about 22 seconds into the video.

It's a new machine, and printed fine for the first 5 or so prints, and then this problem started happening. Now almost every print fails.

Things I've checked:

  • Belt tension seems fine.
  • Belt is not slipping.
  • The bed moves smoothly back and forth, no binding, nothing in the way.
  • When it's failing, it doesn't seem to be because the head is stuck on the print.
  • The screws attaching the pulley to the shaft are tight.
  • The same G-code file that used to print successfully now fails, and not in the same spot every time. Doesn't seem to be related to what I'm printing.

I'm not sure where to go from here. Is this a bad stepper?

Typical failed print


Posted 2020-01-24T14:14:47.640

Reputation: 121

Welcome to 3DPrinting.SE! As you have looked into the mechanical aspects, the electronics are a big suspect in solving this issue. It looks as if it skips a whole lot of steps. – 0scar – 2020-01-24T14:41:42.713

did you check for the possibility of the bed cable chain dragging somewhere, possibly from a piece that fell into the printer? – Trish – 2020-01-24T15:07:13.390

I did check for the cables getting stuck on something - nothing seems to be in the way. I can move the bed back and forth by pulling on the pulley belt by hand and it feels smooth. – stevex – 2020-01-24T15:11:09.657

The only thing that makes me suspect something mechanical is the little "thunk" when it starts moving again, like it got physically stuck and then unstuck. You can hear it on the video. Need a printer whisperer to tell me what that means. :) – stevex – 2020-01-24T15:12:02.323

I hear a thunk like that in 2 cases. 1) putting down first or second layer with insufficient clearance so extruder doesn't release any material & the filament advancer slips. 2) too much material released, making mounds or blobs which solidify high enough that the extruder tip runs into them next layer around. This can push the part and/or drivers off position – Carl Witthoft – 2020-01-24T15:29:12.313

YOu may well have a high point on your bed there - see how your first layers aren't covering very well. – Carl Witthoft – 2020-01-24T15:30:14.167

1In the photo you can see it continues to drift even when it's extruding over nothing. Seems like that would rule out bed movement blocked by the head hitting the model or the bed? – stevex – 2020-01-24T15:40:09.893



AnyCubic Support suggested I swap two of the motor drivers (X and Y) and after I did that, the problem disappeared. I've had a half dozen good prints in a row now, no problems at all.

The drivers are inside the computer module - had to flip over the printer, take off the cover and pry out the top two modules and put them back in swapped. Not difficult, but probably worth getting advice from AnyCubic before going ahead and doing it yourself unless you're comfortable with this sort of thing.


Posted 2020-01-24T14:14:47.640

Reputation: 121

Thanks for taking the time to post your solution! – 0scar – 2020-02-04T07:16:58.273