Fixing the base print profiles to avoid collision and layer shift
With my new Core One, I have been having issues with strange layer shifts or parts being knocked off the build plate after reaching 0.5 to 1 cm of height. I see there has been some discussions on the internet but the fixes are varied: upgrade firmware, belt tuning, pulley screws, cleaning the PEI sheet with dish soap and then IPA... Even after ALL these tuneups the issue persisted. Here is my theory after testing with different types of models and materials (PLA, HIPS, ASA).
The issue tends to happen less or not at all with:
- Solid models with one or few separate perimeters (for example: a vertical cylinder), as there are few travel moves.
- PLA, which barely warps.
On the contrary it happens more often with:
- Printing a model with many different vertical volumes or many of the same model at once.
- Warping filaments (HIPS, ASA, etc).
So, I believe the standard print profiles (0.2 mm balanced and others) lead the nozzle to hit the printed model and the belts to skip.
Based on internet advice I have turned on the two following settings in PrusaSlicer:
- Steeper Ramp before obstacles
- Avoid Crossing Curled Overhangs (Experimental)
They greatly help and I think they should be on by default.
If issues persist after this, try printing in Stealth Mode. I believe the stock accelerations are simply too high for no good reason but to demonstrate fast benchmark print speeds, while risking stability. I have amended all my print profiles to use the Stealth Mode accelerations/speed/jerk as a baseline. If you are in a hurry to print, you can start by lowering only the travel move speed and acceleration, leaving perimeter and infill speed alone.
RE: Fixing the base print profiles to avoid collision and layer shift
Update. Problem is not completely fixed. Yesterday it happened on a multi part print with brims printing ASA. The print was completely knocked off the Satin sheet bed despite it being freshly cleaned with dish soap in water, and then isopropanol. My C1 was one of the first batch, factory assembled. I had z axis groans/squeaks. I now think something happened on z-hop at a certain z height 2-3 cm over 0, where the print head collided with the print, combined with bad bed adhesion.
The following 3 fixes help:
1. Trapezoidal screw retightening
https://forum.prusa3d.com/forum/postid/758965/
"If the z-axis screw is squeaking, it could be the trapezoidal nut horizontal position misalign.Just loosen both screws of the trapezoidal nut 1-2 turns, lower the plate all the way down by menu and than tighten the screws again.It cured my problem with left z-axis yesterday."
This completely removed the Z groan for me, without having to lube the screws.
2. X axis retightening
3. Leveling the bed zero to help print adhesion
https://www.printables.com/model/1289015-prusa-core-one-bedlevel-correction-dust-cover
https://www.printables.com/model/1485727-z-axis-gaugetool-for-bed-leveling-on-core-one
After all this, the belts should be retuned.
If this doesn't work, I'm at my wits end. I've never had this many failed prints on a MK3S with textured sheet on the same filaments (HIPS, ASA). I just bought a Glacier sheet on the off chance the Core One Satin sheets are just bad, but I'm pretty sure it's the print head knocking into the models.