This is the second time now that I’ve been printing something and one spool has run out. The AMS did not automatically switch to the other spool in it (maybe because it’s a different vendor even though it’s the same material and color?). Each time the print sat for a bit (an hour or so) before it was noticed (Handy is garbage lately with notifications for ANYTHING but that’s a different story). I got to work, loaded a new spool and hit resume and on both prints there’s a noticeable layer shift when the print resumed. I’m not yet sure if the print will be useable as I have to print the rest of the parts that go along with it.
I did see a ton of other threads dating back to 2023 on this and not just on the H2 series but nobody seemed to have a solution except one that had printed dust guards that were interfering with homing. Any ideas?
I have the same problem, but withoud filament change. In the print he shifts the layers a little bit. After that, the printing is good again. I didnt have a solution for it and the Bambu Support was not helpful with tips like cleaning the bed.
@Epic_Will You need to confirm in Studio, if your filament is paired for replacement. You can see that before you start printing.
These kind of artifacts are usually caused by cooling down of the part. So it’s most likely shrinkage related.
The fact that you have a different brand, might also introduce flow rate deviations due to thicker/thinner filament.
A long pause during printing, sometimes already a couple of minutes, is usually enough to get this behavior.
If there is a real shift (everything moved in the same direction), there might be an issue that the steppers have been disabled, but in such cases that is quite unlikely.
Well the bed stayed at 90C and the chamber stayed at 65C while it waited, and when I got in I installed a new spool of Bambu ABS (the same kind it started printing with) and this is the result.
The AMS is set to auto-refill as it does this all the time when there’s two black Bambu ABS spools in (typically in slots 1 and 2). I only have one white Bambu ABS and slot 4 was some Hatchbox ABS that I assumed it would use but decided it wanted to wait until I refilled the Bambu ABS instead.
The AMS was setup so it knew it was white ABS, it just knew it wasn’t Bambu ABS that the print started with. Maybe I’ll just lie to the printer and tell it it’s Bambu in slot 4 so it’ll switch next time.
I’m fairly certain it is layer shifting rather than shrinkage as it’s not uniform around the part, it is indeed offset slightly, I’m just unsure of which direction as I didn’t notice it on either part until it was removed from the printer.
I’ve also had this issue with my Ender 3 at home where the filament ran out overnight and it just sat until the morning and I popped a new spool on - no AMS obviously. But it also continued and the print was flawless.
The chamber temperature of 65C is no guarantee that it doesn’t shrink. You print at 240-260C and when you get to the next layer, that hasn’t cooled down to 65C yet.
The long wait, might also cause a part of the XY belts heating up non uniformly due to the parked position. So possibly belt in center chamber is around 65C, but the part in the back might be a bit cooler because it’s closer to a cooler wall.
There is no real reason why the steppers would move to another location during a pause of an hour. IMHO it is something thermal. I had no issues so far with the AMS picking the sister spool. But when I had a break af longer than 10 minutes, I had similar issues.
From a positional/geometrical perspective, most of the time no issue, only visually it’s less attractive.
