XL Loose Belt Retainers
Check your belt retainer screws!
This is just an FYI. I had been having seemingly random homing errors. I started with checking belt tension, using the both the belt tuner app and by checking the carriage against the front of the frame. I could never get the tension perfect on both sides, 1 was a little loose and the other to tight. They were both close so I let it go.
I continued to have weird homing errors and random crashes. During one of the crashes the belt retainer cover got some scuffing on it so I decided to reprint it.
Low and behold when I took the cover off all of the screws on both belt retainers were loose and once the cover was off the upper belt fell out of the retainer.
I have never taken this apart so it had to have come this way from Prusa, or they worked themselves loose form heating and cooling cycles.
So I added some thread locker and put it back together. When I tensioned the belts this time I easily got both sides perfect.
So next time your doing maintenance it might be for to make sure the screws on your belt retainer are tight.
RE: XL Loose Belt Retainers
Hi Brian,
I am experiencing similar issues you discuss. I just did belt tensioning, and did it poorly. I way overtightened one side, and after experiencing layer shift, went back and tuned everything over and over. finally homing tower was flawless. On some prints, everything is great, but on multicolor prints, I'm noticing shifting and drifting. Are you talking about the X carriage cover? the one with the small "original prusa XL" logo?
Im attaching a pic or two.
My homing tower prints flawlessly, but allowing the slicer to position my keychain close to the print heads, and I think only when using multi colors in one layer, my prints are skewing. Like the carriage is being jarred a little further out of place each time a tool changes. The red and white keychain at an obvious slant, it cut off in the middle of "GKC" when tool #3 crashed instead of being docked into the carriage having drifted off course. the Sliver GKC keychain slowly drifted until the printhead crashed and then I followed the instructions for the machine to re-home itself and finish the print. (I used less filaments, resulting in less tool changes, making the transition a little more prolonged.) Printing two keychains, one at the very front of the bed, and one near the back is showing they both are skewing toward the front of the bed.
RE: XL Loose Belt Retainers
Hi Brian,
I am experiencing similar issues you discuss. I just did belt tensioning, and did it poorly. I way overtightened one side, and after experiencing layer shift, went back and tuned everything over and over. finally homing tower was flawless. On some prints, everything is great, but on multicolor prints, I'm noticing shifting and drifting. Are you talking about the X carriage cover? the one with the small "original prusa XL" logo?
Im attaching a pic or two.
My homing tower prints flawlessly, but allowing the slicer to position my keychain close to the print heads, and I think only when using multi colors in one layer, my prints are skewing. Like the carriage is being jarred a little further out of place each time a tool changes. The red and white keychain at an obvious slant, it cut off in the middle of "GKC" when tool #3 crashed instead of being docked into the carriage having drifted off course. the Sliver GKC keychain slowly drifted until the printhead crashed and then I followed the instructions for the machine to re-home itself and finish the print. (I used less filaments, resulting in less tool changes, making the transition a little more prolonged.) Printing two keychains, one at the very front of the bed, and one near the back is showing they both are skewing toward the front of the bed.
Yes I am taking about the belt retainers under the Prusa XL cover on the carriage. If you take that off (it just pops off) you'll see 2 clamps that hold the 2 free ends of the belts.
I'd check those.
In your case 2 other things that I'd do is make sure that your print head docks are not loose. They are held on by a single screw and are hard to get tight. You can check to see if any are loose by manually removing the print head from the dock, and then trying to wiggle the dock. It should not move at all. If it does you should go back thru and tighten them all. This task can be made easier by removing the honeycomb metal piece behind the docks on the back of the printer. It comes off pretty easy just by removing the screws on the edges of it. Taking this off just makes it easier to get to the dock screws. I'd then recommend putting a small dab of blue thread locker on the screw so that it doesn't come loose again. I used 243 Loctite, but some people are scared to use that because they are worried about getting it on the plastic. I had no issues.
Lastly after checking all of that you might consider rerunning the nozzle offset calibration. I had some weird very slight shifts when changing nozzles, but making sure my nozzles were super clean and rerunning that calibration solved that fit me and I haven't had an issue again.
Good luck.
RE: XL Loose Belt Retainers
@Quickset45
What firmware are you running and have you recalibrated your phase stepping at all?
I've had a similar "random weird slant issue" in the past but never really figured out what was causing it other than maybe the 6.0.0 alpha firmware with it's (back then) new phase stepping feature being wonky. https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/3819
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RE: XL Loose Belt Retainers
Some updates
my belt retainers were not loose. the gear on the X & Y motors were not loose. My belts are perfect.
I now believe its the 2.8.1 slicer, or my model? I'm running firmware 6.1.3 I went through all calibration including phase stepping, nozzle offset, tool head alignment.
I drew and printed a 100mm x 100mm x 100mm hollow box with 1.35mm walls. (exactly (3) .45mm wall passes, I 'm using .4 mm nozzles) The box printed 100% accurate to the line on the back edge of my print sheet, (absolutely no skew) The box measured in all dimensions less than 1/10th of a mm. 100.1, 99.9, 100.04, etc. I calipered the box from corner to corner and it was square within 2/10th mm. across 141.4 mm diagonal measurements. Wall width was perfect.
this is the .stl I'm trying to print ^ Its small, I'm using a soluble filament around the key ring loop to print the shield point up. I recessed tiny lines in model to separate color areas for easy smart fill coloring.. maybe thats throwing slicer off?
I think its the slicer version, or maybe the model?
RE: XL Loose Belt Retainers
Just to answer unanswered questions, my docking lugs are all tight, no movement. And I also calibrated input shaper. Phase stepping is enabled.
RE: XL Loose Belt Retainers
Can you upload your 3mf so that we can look at that.
One other this to check is the dock location calibration. It's possible if that's off that it might be crashing when trying to dock. Unfortunately crash detection is not working currently.
RE: XL Loose Belt Retainers
I just printed 4 color box, no issues.
I put 3mf files in dropbox folder
RE: XL Loose Belt Retainers
The solution to my problem lies in the slicer version 2.8.1
slicer settings that gave me problems and hideous results:
Perimeters: 1 , Generate support, do not generate auto support, (Paint on supports used) infill density 80%, honeycomb, support style grid, Z distance 0 (soluable), rectilinear, heavy top interface, bottom interface off, interface patters spacing 0, support on build plate only, XY separation 0, Synchronize with object layers yes. Multiple extruders: Support material/raft/skirt/extruder: 5 Support material/raft interface extruder: 5 Wipe tower extruder 1
Slicer settings with absolutely no problems (same exact .stl)
Layers and permeters all default. Infill default. skirt/brim off. Generate support material, Auto gen supports, organic, .2 detachable rectilinear, pattern spacing 2mm, XY separation 80%, support material/raft/skirt extruder 0, support raft interface extruder 0.