Bad Layer Shift on Y axis!

Well, it was a long print with lots of “short infill” that definitely gave the XY axes a workout. But the room was cool and the fan is blowing straight at those three chips, so it is just hard to imagine they overheated. Still, having ruled out belts/pulleys/bearings/etc, I don’t know what else it could be.

Agree. I’m kind of surprised the one Aleph installed on the Z driver chip fell off. I haven’t heard anyone else with a mini mention that issue. I have used those exact same heat sinks on VRAM and LED drivers; they are low mass (not much weight to hold) and the adhesive pads are very sticky. Never seen one fall off before. Of course video cards don’t violently vibrate back and forth when they do short infill. :unamused: :slight_smile: It’s also possible the installer at Aleph just didn’t seat it well, or the surface was contaminated.

In any case, I decided not to trust the adhesive pads. “Thermal epoxy for the win” on all three of them. :laughing:

Thanks for your help!

It sounds like you found the problem, but one other possibility it could have been (for people looking for solutions but with heat sinks intact), is that the filament can bind up. In one of my early over night prints the filament sort of tied itself into a knot (new roll) – somehow it continued to pull through but my print got shifted over on the Y axis by 15 mm or so. I had been using the stock filament arm but replacing that with spool centers on bearings solved that issue and it hasn’t happened since (almost a year).

Yes - I will be posting a follow-up with details tomorrow, but the heat sinks seem to have completely fixed the problem. I ran the same print today (8+ hours, plus a few other parts that were another 2+ hours) and everything printed perfectly! :slight_smile:

Was it shifted on Y, or X? I would expect filament binding on the Mini to affect X and not Y, since it would be restricting the carriage movement (X) and not the bed (Y).

I’d like to see how you rigged that up, if you could post info and pictures.
EDIT: Nevermind – Found it on Thingiverse. http://www.thingiverse.com/thing:859929 Thanks! :slight_smile:

Success! After heat sinking the stepper driver chips, no more missed steps.

To summarize for future readers of this thread:

  • I attempted an ~8 hour print, and it failed with bad layer shifting due to missed Y steps (see photos in first post of this thread).
  • After ruling out mechanical problems like belts, pulleys, power, and outside interference, I concluded an overheating stepper driver was the most likely cause.
  • I opened the electronics enclosure and found that the Z stepper driver heat sink (installed by Aleph Objects, using adhesive pad) had fallen off the driver chip and was “loose” in the enclosure. Luckily it didn’t short anything out on the mini-rambo, but could easily have done so.
  • I cleaned the failed adhesive pad residue off the heat sink and Z stepper driver chip, grabbed (2) more identical heat sinks, cleaned the X, Y, and Z stepper chips with alcohol, and attached a heat sink to each one using Arctic Silver Alumina thermal epoxy.
  • I reprinted the same model using the same settings, software, and environment. It printed perfectly – no missed steps on any axis.

Photo and video link showing completed project are attached. This used 0.30mm layer height and “fast” settings on Simplify3D, so the quality is a bit rough but it works great!

Thanks to everyone for their suggestions and help, particularly Kmanley57 for identifying the chip locations.


I have the Main body printed 21 hours 52 minutes, looks pretty nice. The designer did a very nice job.