Yes, but why would you need to take care of that manually? It should be automatic. There is no need to crash. And like I said, it can be prevented. Running modified G code for days now, no issues anymore and no more crashes.
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Well i manually have to remove the finished print. So raiseing the bed is not hard since you are there at the control screen.
I donât see it as a crash, its something that Bambu Lab decided to do to keep from damaging the nozzle or the bed. Even Prusa makes their stepper miss steps checking z height. 
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Yeah, the printer companies have no need to justify their choices to the user. If they had to detail every decision, explaining their reasoning, then listen and reply to all the counter arguments from the âarmchair expertsâ , it would take an army.
Even tracking down the people who decided on a single issue and getting them to recall a chance meeting discussion between three people on the factory floor six months ago to find the answer to a single decision âŚ
Think people. They ainât explaining this or any other Firmware choice.
EDIT: Not aimed at you @Barryg41 
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I have had this issue a total of 5 times since I got my X1C. 1 time was a few days after getting my X1C and lowering the bed fully prior to homing, 3 times were while printing the Hydra AMS sections (forgot to raise the bed EVERY time) and the last time was after printing something else that left the bed lowered at the end.
Honestly, if I knew that it was just noise and that no potential existed for causing damage, Iâd be totally fine ignoring it. Itâs just that it sounds like the belt slipping on the drive sprocket.
I am not expecting anybody to justify any design decisions to me, but my expectation is that any company capable of developing a world class product like this is more than capable of solving such a basic programming issue in a ridiculously short time.
When I got my Mavic 2 Pro a few years ago, I marveled at the insane level of engineering and sheer amount of brainpower that went into designing that amazing machine. The only reason I bothered to learn more about Bambu Lab was after reading about the companyâs origin. DJI broke ground on a new era for drones and photography/videography. Bambu Lab is doing the same for 3D printers.
Regardless, a bug is a bug. Unless Bambu Lab engineers intended for the Z-axis to generate horrible noises during automatic operation, then Iâll consider this to be a design or programming error and keep my fingers crossed for it to be fixed.
Iâve been a mechanical and control system engineer for years. A funny (and somewhat relevant) memory I have is many years back when I was asked to solve an annoying issue with a product routing system. This was an issue that we all knew about, but it had not been corrected due to other tasks with higher priorities. When my manager asked me about the issue, I began to explain why the issue still existed. He stopped me after a few sentences and said, âI donât really care why this is still a problem. I just want to know if you can fix it.â I stopped and replied with, âsure!â His response was, âWell then, go fix it.â lol And just like that, it was fixed. 
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This has happened to me since day dot. If the printer finished a tall print. The only way to get it to stop is by homing it beforehand.
Thatâs my experience in any case. I would have thought they had fixed it by now
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Ive been having this issue since updating firmware. I dont understand how the printer does not know or check z axis position before attempting to move it beyond its lower limit. Itd also be nice for the stepper motors to have an over torque alarm before skipping belt teeth.
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if the solution proposed by @djeZo888 is the one that avoids this horrible noise, which just woke me up, then BL should take this into the next Studio version, for Christ sake. I knew it, forgot it, just printed something tall and⌠My god, terrible noise.
I suspect this sound is the stepper motors trying to move either the belts / table to a position beyond the physical limitations of the bed / head. I believe the sound you are hearing is the stepper motor âSkippingâ a step / movement. This is a common thing that can happen to stepper motors when you try to move them, but they physically canât move.
This makes perfect sense for what you guys are describing and when it is happening, and why it only does it when moving the bed or doing maintenance on the printer and calibrating. It also explains why it doesnât happen afterwards. Because once it misses so many steps, it then becomes âIn Syncâ with where the driver board thinks the motor is, and where it actually physically is. The printer loses track of the bed/heads current position because you either moved it manually or put it somewhere it wasnât expecting so it tries to move it beyond its physical limitations. So the stepper motor can not physically move to where the coils inside of it are trying to move, so it âskipsâ a step.
Will it damage the stepper motor? No. The stepper motor just âskipsâ that step and re-orients to the next stepâs cycle. It sounds scary but it doesnât cause damage to the stepper motor. Especially not for the very brief second or two it happens. It just sounds loud because the motor kind of moves forward then can âflingâ back really hard to the previous step. (These are usually very small movements, like 1 degree or so) It kind of moves back and forth really hard. But this doesnât damage the motor in any way, but causes the motor to move forwards and backwards in kind of an erratic way.
Can this cause damage to other components? Possibly, but probably unlikely. Stepper motors generally have low torque. Their main goal is precision movements, and as a result of that the coils that actually do the moving are much smaller than a traditional electric motor. An electric motor of the same size would have maybe 4 large wire coils, giving it much more torque when moving, stepper motors have maybe 10-20 coils (completely depending on the motor design itself) in that same space that are much smaller, but allow for much more granular movement. So usually you will find stepper motors have much less torque.
That being said, there are ways to increase the torque of the stepper motor through some electrical magic⌠i.e. high voltage pumping to generate the induction in the coils faster, using larger coils by increasing the physical size of the motor, and other magics. But even then, the torque is still usually fairly low. I would imagine that this has been considered by Bambu Labs and the mechanical components can handle the skipping of the stepper motor without taking damage.
This is all speculation from my knowledge of how stepper motors work, and what I have also heard from doing maintenance on the Bambu myself. This is why you hear it after doing some kind of maintenance or the bed being too low and it trying to move the bed down still. But then it gets back in âsyncâ with where the controller board thinks it is, and where it actually is, and it no longer tries to extend out beyond its capabilities.
In my case, it was definitely the Y axis, as the bed was nowhere near the bottom.
It also had an effect on the position it was printing in. The purge line was about 12mm to the rear of where it usually is. My print proceeded normally, but I surmise that if I had a full plate of objects, it would have been a problem.
Iâll try a calibration later.
Didnât realize until I posted that it was an old thread.
Is this still a known problem?
I just had the same issue and am googling around. I heard motor overloading right after the first homing, when the extruder went to the poop chute to purge some filament. My purge line is a few mm to the rear too. Did you find any answers?
In my case, it was user error. I installed an LED strip across the front, underneath a metal plate. It REALLY improved the lighting, but unfortunately, thatâs when I started getting the symptoms I mentioned. Turns out that the head was hitting the plastic of the LED strip, causing it to think it was at the farthest point to the front, and homed accordingly, making a lot of noise as it got to the rear, and being off by 12mm or so. Then of course the purge line was not where it should be.
Check to make sure the head can get all the way to the front, as thatâs where it figures out where it is.
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The Z below minimum sounds horrible but is perfectly fine. It will not cause any damage. The motor isnât anything near capable of damaging the Z belt. Some older stepper motor driven devices (Commodore 64 and Apple-II floppy drives come to mind) do this sort of thing on purpose as a mechanical homing strategy.
X/Y grinding noises though ⌠that doesnât sound right. Iâve never had that happen to me.