Can someone at Bambu Lab explain why the bed vibrates up and down during the startup process?
We are curious about the purpose and benefits.
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The X1C and P1P both have input shaping and an acceleration sensor. During initial calibration it tests for all the frequencies and what vibration they cause.
During startup, it tests some of those frequencies found to test if the results have changed, e.g. by moving the printer to a different surface and it would require another full calibration run.
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It may also be to relax the load cells in the bed. They are used to level the bed, I assume it’s done by pressing down a set amount using a preset weight value and measuring how far it had to travel to attain that weight. The amount of weight is probably very small and to prevent miscalculations happening due to the bed not returning to zero after a few cycles, it will shake the bed to relax the load cells and then set zero on them before the next cycle of leveling begins.
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This does not apply to the bed movement, does it? I think it is only for X-Y movements.
I would love to know more about this too. I’m sure it has something to do with resonance, and I note that all three vertical screws are linked to the same belt, so there is no bed levelling by tilting -presumably the machine is adjusting the whole bed on the fly many times a second.
The answer from lasermike is the right one.
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Would be nice if it could skip some of these print startup steps and only do it once it’s powered off/on or when its acceleration sensors sense the device was moved. Seems unnecessary to run them every print.
Wait until it plays music for you.
Hey, I don’t think Bamb Lab printers have load cells. I think there are three peizo speakers they have cleverly used as impulse sensors. Shown here. They are in the build plate at each lead screw to detect impulses such as a collision with the print nozzle. Additionally, it is possible to use generic stepper drivers to sense collisions, as they have a fault pin that goes high when the current spikes (in a stall) or if it overheats.
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Looks like you are correct. There wasn’t as much info in the early days so I guessed at the technology. Instead of “relaxing load cells” it may be doing a sort of micro calibration where it vibrates the assembly, checks for resonance then carries on.
I think there is also a repeatability aspect because it does that shaking several times. It would validate that it will hold the calibration throughout a long print with lots of travel motion.
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Have you heard the steppers play music yet?