Bed slams into the bottom if you stop two prints before they start

Bambu Lab X1 Series Bambu Lab X1C
1
  1. Start a print but stop it before it actually starts.
  2. The bed lowers to let you access.
  3. Start another print and again, stop it.
  4. The best lowers to let you access.
  5. If you try again it will lower to start and slam into the bottom of the case because there is not stop. It’s not being home’d or something after the stop
2

When you use the word “Slam” can you elaborate?

Are we talking a sudden jarring action like a car slamming into a pole, or are we referring to the bed motion reaching it’s limits and not being able to travel further?

If I understand you correctly, the bed is already near the bottom of the print space volume. Upon starting a print job, the printer bed lowers slightly before calibrating its position. If you stop it during that process and start a new print, the bed, already close to bottoming out, lowers further, causing a grinding noise.

Do I understand this correctly?

3

The second one, the bed reaches it’s end so it sits there and grinds into the bottom. It’s very loud and I’m assuming not good for the printer.

Yeah, nothing resets it if you stop the print so it stays lower, then if you repeat that it just continues to go lower because the homing doesn’t appear to happen until latest in the start sequence

4

Well… welcome to the club. This is a known bug… errr… feature that Bambu has actually made an effort to resolve in firmware. How’s that working out for us?

Bottom line is that it’s a design defect. It appears Bambu relies on relative reckoning on the print bed and tool head. The correct answer would have been to incorporate a cheap limit switch.

This was debated and discussed in this post:

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5

What does homing the printer do after stopping / finishing a print ? on the x1

6

Homing will work, it doesn’t home if you stop the print before it’s started though. The fix might just be changing the homing step to be the first thing the gcode does everytime

7

Oh, maybe it’s not just if you stop the print. I printed a tall print and everything finished fine. I printed something else after and the same issue occurred, the bed went down and hit the bottom.

8

It’s a known bug and is independent of stopping the print.

I always raise the bed a few inches which is a major hassle.