Massive Z crash during XYZ calibration
Hi all,
Sorry my first post is so negative, but I wanted to share my misfortune with this. Background: I successfully assembled my mk3 kit earlier this week, and printed several of the example files with no problems. One thing I noticed, however, was that the Y-axis motor was not quite aligned properly (I'll post another thread with my analysis of this later), so I made a couple of modifications and reassembled.
Now, I thought that it would be a good idea to do a new XYZ calibration since I had messed with one of the axes, but this turned out to be a massive mistake: during the calibration (second point of the level check, front-right corner) something went badly wrong and the z axis tried to drill straight down through the bed. 😯 I don't know exactly which parts took the strain, but the corner under the extruder nozzle got pushed down at least 5mm (according to my panic-stricken memory; I didn't measure it) before I hit the stop button.
After releasing the z axis I did a quick check for any mechanical problems (axes still move, PINDA probe at the right height, etc.) and ran the calibration again (with a finger on the stop button) with no issues. So the good news is that the printer still functions - I have something printing right now as a test - but the bad news is that I think the incident has left a permanent bend in the bed (plus I'm now paranoid that it's going to self-destruct at any moment). Fortunately the automatic mesh bed leveling seems to be able to handle it for now, the z axis motors need to do about a quarter-turn when moving from back-left to front-right corners (is that semi-normal? I'm pretty sure it didn't need to do that before the incident...).
Any advice? I've no idea what caused the incident, especially since the PINDA probe seems to be working fine otherwise (and it was the second corner that crashed, so it had already done the first one successfully). I had a quick look at Prusa's store to see if I could order a spare y carriage+bed, but they don't seem to sell them. Worth contacting customer support?
Thanks,
-tombsar
Re: Massive Z crash during XYZ calibration
I had a similar experience. I changed filament from PLA to PETG and was trying to dial in the first layer. My z-axis went all the way to the top, and the rammed down into the board at the front left corner (where it puts the initial line down before creating a skirt). I've got a nice dent in the removable board.
Thankfully, I was able to quickly hit the X on the display to kill it before it did additional damage. Since then it's been able to print ok, but I haven't tried going back to PETG yet.