Just got a Bambu Lab A1 Mini 3D Printer!
Unfortunately, at the start of my third print, some weird shit happened which it never recovered from. It stopped printing, an error popped up on the display, so I rebooted it and tried again.
The Problem
When homing, the toolhead will go towards the purge wiper on the left side and wiggle around, as per usual. Then, it should head back towards the right side and the X axis homing should be completed.
However, in my case, it seemed to be trying to go out of bounds and further left. It jitters around on the left side and a grinding sound of gears can be heard.
The printer detects something is wrong and stops with the message “homing failed”.
Attempt 1: Remove the purge wiper
As suggested by Bambu Lab’s live chat assistant, I removed the purge wiper and ran the homing again.
It’s a known issue of problematic purge wipers messing with the homing, as it’s a sensorless homing which works by moving until it feels a resistance, an increased motor load, which indicates the end.
Anyway that didn’t work. Exact same behavior even without the purge wiper.
Attempt 2: Factory reset
In this post on Feb 2024 a user reported a similar problem, on which Bambu Lab reported a firmware bug being the cause.
I had already updated the firmware to 1.08 before my first print, and the bug is probably fixed already, but because I’ve got nothing else to do I just tried a factory reset.
No luck - upon running the mandatory calibration, it grinds at the left side and then at the right side, then errors out with “calibration failed”.
Solution
Customer support on the Bambu Handy mobile app got back to me. Suggested a re-tensioning of the X axis.
Claude actually found this as one of the possible issues, but with it being amidst 5 or so other candidates, I ignored it 😭😭😭. Also because by manually pressing down on the rubber strip, it felt quite tensioned already.
In hindsight, that little difference was in fact the problem.
Following the guide they sent, I tensioned the X axis belt:
- Unscrew the screw at the back of the toolhead, around the bottom side
Note: Do not fully unscrew it. Use 1 turn only. - Manually move the toolhead around 3-4 times
- Retighten the screw
Probably because I didn’t tighten the screw enough, upon retrying the homing, it errored out without the toolhead moving at all.
I simply tightened it a bit more and the problem is solved.
Back to printing!
Understand?
Don't doubt. Don't be afraid. And know. Knowledge will save all.