Bambu A1 less than 2 months old. PETG. A couple of times while printing i will hear a thunk from the bed, like it hit something. The bed moves to the far rear position, the print head moves to the poop station, waits about a second, and then resumes printing as if nothing had happened. No misalignment.
This sounds real bad, but maybe it’s normal … ?
You might want to record a short video of it. It’s really difficult for anyone to get a clear sense of the noise from text alone, or even from photos. You’ll probably end up needing a video anyway, especially if you decide to reach out to support since you’re still under warranty.
Problem is, it happens so infrequently the video could be 30 minutes or more. I have not seen a pattern of it happening.
Do you have the timelapse activated? The a1 for timelapses moves the toolhead to the poop area, centers the bed and takes a picture and continues printing.
No. That happens every layer, right? Not turned on.
From your description it sounds like the printer detected an issue, such as unexpected movement. What you’re hearing/seeing is the printer re-zeroing its position, so that it knows where it’s at.
How stable is whatever you have the printer sitting on? Is that object possibly getting bumped or knocked?
The printer is on a table made from an old solid core commercial door … seems to be stable.
I have unfortunately lost 2 prints recently, both were long prints, many hours, and both were tall. Latest one was about 9” tall and used over 850g of filament. During the last hour of printing is when i heard the thunk most often , and there were several layers that were misaligned. Talking on another forum, people are thinking the height and weight of the object were enough to cause inertia bumping … which could possibly explain the noise. So i have ordered a p1s to hopefully avoid that problem in the future.
That’s a definite possibility, as it’s significant for what is a small and light weight printer. I can see in you photo that the issue happened more often as the model grew, which seems to reinforce the theory.
Another option you could have tried was to run such a job at half (“silent”) speed. I do this on my A1 when I have tall jobs, especially those with tall supports, that are at risk of breaking or falling. It makes the whole process somewhat gentler.
inertia bumping sounds much smarter than waggle
But yeah, tall big stuff on a bedslinger will waggle. As the center of gravity of the part moves higher off the plate, the force is working harder against anything that is bearing it, stuff flexes. There’s a new “tall print mode” that IIRC you can dial in to make it slower as the build progresses, to kind of counteract that ever-growing lever force
Actually the first 90% of the print came out very nice, all of the issues happened in the last hour and it was too late to shift modes.
It’s worth noting that you can change the speed any time it’s printing. Not the speeds in the profile of course but the machine speed, next to the lamp button in Bambu Studio.