CORE One Layer Shift Diagnosis
Hi Team
Posting here as i've been having significant layer shifting on prints that seem to go more than 5+cm off the build plate despite my attempts to follow guides/suggestions around the internets.
Background: New Core One kit build as of last week, mostly went without an issue and took my time over a few days as time allowed - shall preface this is my first printer but have been wanting one for years and have been casually watching videos of the topic for about 7y.
I've been printing all sorts of calibrations in Orca to get some nice looking test prints. Goal has ultimately to print a drybox mod as I pretty much live in a 60%+ humidity location ( https://www.printables.com/model/1199587-prusa-core-one-dry-box-mod) to play with some TPU and other humidity sensitive filaments.
All the tests have been great, dialed in the temp (eSUN PLA+ black and orange, going for 220c because there's not much difference between 210-230 depending on speed coming out shiny or slightly matt), pressure advance tests are looking nice so the top layer is pretty, thinking i'm ready.
First up, i've had issues with the 'auto home' just bumping forever and eventually causing a printer reset (after many mins) and then other times after resetting the printer it'll be fine. Just tonight i've re followed the steps for XY belt alignment/setup and noticed a bit of play on one side so managed to get both sides by pushing them against the front nice and flush where there was no further movement while the extruder was in the front center.
I then went with the recently advised 98/92 top/bottom belt hz with extruder front+right and after doing so moved it back to center+front to confirm there was still no play and... here we are.
I've had a benchy fail about 3cm up which hilariously shifted about 3mm right and 3mm back, then come back and finish perfectly.
I've had the descant holder for the drybox fail now twice at similar positions with similar amount of failure but in only one direction.
Will try to upload photos of examples.
Things tried so far:
* Using the Prusa app (and 2 or 3 times before, a laptop with a decent usb microphone from Blue stuffed into the chamber thinking my phone mic was not up to the task (Android -OnePlus 13)) aligned top and bottom belts to the recommended hz, however, potentially overlooking the previous requirement of having no play/whatever those are called touching the front sections with no wiggle.
* Have moved the printer from a wobbly metal shelf (when it was in action, holy) to sitting on some tiles with no movement.
* Many sessions googling/youtubing on the topic of layer shift and oh my there are some impressive examples far worse than i'm experiencing. Most recommendations seem to be blanketing suggestions which leads me to think its an issue with the physical printer setup.
Would very much appreciate any suggestions or links of things to try. I have had successful useful prints so its not all bad news but this shifting issue is annoying as it creeps in after I have seen that the first few layers are all good expecting the rest to have no issue. 
RE: CORE One Layer Shift Diagnosis
Seems I didn't have a really good example of the issue in the posted pics, here's what I mean (it's gone 5mm+ to the left):
RE: CORE One Layer Shift Diagnosis
Posting here as i've been having significant layer shifting on prints that seem to go more than 5+cm off the build plate despite my attempts to follow guides/suggestions around the internets.
...
First up, i've had issues with the 'auto home' just bumping forever and eventually causing a printer reset (after many mins) and then other times after resetting the printer it'll be fine.
I had the exact same problem. From my understanding, this is caused by improper belt tuning and/or the gantry being bent. At least it was in my case. I'm assuming you followed the belt tuning guide here: Adjusting belt tension My mistake (before they revised the instructions) was plucking the wrong set of belts instead of plucking them in front of the gantry. Try using the "old" tuning method of 85hz on both belts first.
RE: CORE One Layer Shift Diagnosis
Heya Higer, that seems to be the case (belt tension or play) from what i've read. I did manage to get it to finish tonight without issue, 3rd attempt printing it alone on the build plate.
I did notice some weird black spot in one of the pics I took on the cage and more research suggests it can be caused by the print head hitting a printed part and getting out of alignment so I dunno.
I've tried the 85/82 but not enough to properly test so am back on the recommended 98/92 with no play when pushing the top sections forward and shall keep sending prints to see how it performs.
RE: CORE One Layer Shift Diagnosis
I did notice some weird black spot in one of the pics I took on the cage and more research suggests it can be caused by the print head hitting a printed part and getting out of alignment so I dunno
I had read/heard that as well; where in some cases the head bumps over an infill line and gets out of alignment. That cause of which (I was told) was due to the belts being too loose.