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Hot end dove into the bed mid-print  

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DanieTownArt
(@danietownart)
Active Member
Hot end dove into the bed mid-print

I was printing some visors, and after like 24 of them, the hot end dove into the part I was printing like 3/4 of the way through the print. I scrapped the part and went to auto home the printer and it dove into the bed again. 

went through the calibration wizard again and it takes the z all the way to the top, then dives right back into the bed again. 

Thought it might be an issue with the pinda, but all the tests that were recommended suggest it’s fine. I dropped it a bunch anyway just to see what would happen, and it was fine on the first spot of 9, but dove into the bed again at the second. 

I’m going to pull the bundle of cables apart a bit more to see if maybe there’s a break in the pinda cable, but I’m not convinced that’s the issue since it started out by just diving into a 6mm high print. 

anybody else got any better ideas? It’s difficult to get stuff shipped right now, and I wanna get back to printing visors ASAP. 

Posted : 02/04/2020 6:18 am
DanieTownArt
(@danietownart)
Active Member
Topic starter answered:
RE: Hot end dove into the bed mid-print

Sorry: it’s a mk3, built from a kit over a year ago and has been printing flawlessly until this. Just updated the firmware to the newest today wondering if that may have helped the problem. 

Posted : 02/04/2020 6:20 am
JPLau001
(@jplau001)
Eminent Member
RE: Hot end dove into the bed mid-print
  1. Did you slice the visor parts from a STL or did you use supplied gcode downloaded from the internet?  If you used downloaded gcode then it may have altered your printers settings and stored the changes in the eeprom so they are "permanent" until you clear them.
  2. After the firmware update, did you reset the your printer settings back to factory, store those into the eeprom, and then rerun the full printer calibration from the start?

Keep an eye out on the extruder Pinda probe's LED while the printer runs the calibration.  This LED should go off whenever the probe is triggered by the either a steel plate or the heatbed calibration points

This post was modified 2 years ago by JPLau001
Posted : 02/04/2020 8:51 am
DanieTownArt
(@danietownart)
Active Member
Topic starter answered:
RE: Hot end dove into the bed mid-print

Nope, the code was mine. And I was printing the same file that had been previously fine. Weird eh? (And no, I’ve only ever used my own generated gcode.)

 

I did *not* restore back to factory though. Will give that a shot. 

Posted : 02/04/2020 8:58 am
stewartr
(@stewartr)
Eminent Member
RE: Hot end dove into the bed mid-print

I also had a similar problem recently. I was printing a model that I'd printed before. Towards the end of the print the head paused, rose a bit then homed x,y to front right (I've seen this before and thought it was maybe a crash recovery, but no crashes were ever logged). Following that it went back to the print position and looked like it was going to continue the print. But it kept going straight down - it forced its way about 1/4 into the model before I managed to stop it. Thankfully I'd returned to the room to watch it finish the print!

The PINDA can't have anything to do with this because it was printing well above the bed by this time.

This means I can't leave the printer unattended at any time...

This post was modified 2 years ago by stewartr
Posted : 02/04/2020 3:29 pm
Iamcubsman
(@iamcubsman)
New Member
RE: Hot end dove into the bed mid-print

I am have this issue also. My printer was factory assembled and delivered in Nov/Dec 2019. FW version is: 3.8.1-2869 . 

- I have deleted all data and reset to factory settings.

- Re-installed and updated Prusa Slicer to latest version.

- Tried slicing and printing multiple files.

- I monitored the LED for the PINDA sensor and it seems to be functioning/responding appropriately.

- I went through the out of box setup again but when it gets to the first layer calibration step, it never starts. The same happens when I abort it, clear the "you haven't calibrated" message and try to manually start first layer calibration. 

- It is also crashing into the X and Y stops.

- It does not retain calibration settings.

Posted : 02/04/2020 9:24 pm
DanieTownArt
(@danietownart)
Active Member
Topic starter answered:
RE: Hot end dove into the bed mid-print

I’ve just reset it to factory settings; will give it a shot at calibration again. 

Posted : 02/04/2020 9:37 pm
cwbullet
(@cwbullet)
Illustrious Member
RE: Hot end dove into the bed mid-print

@rbrianloveridge

I had similar issues.  I fixed it.  It happened again.  I replaced the PINDA and it hasn't happened again.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 03/04/2020 2:01 am
DanieTownArt
(@danietownart)
Active Member
Topic starter answered:
RE: Hot end dove into the bed mid-print
Posted by: @charles-h13

@rbrianloveridge

I had similar issues.  I fixed it.  It happened again.  I replaced the PINDA and it hasn't happened again.  

Yeah, I have another on the way. Just caught it being weirdly inconsistent when messing with it today, so it’s got to be the probe.  Thanks guys, so much. 

Posted : 03/04/2020 4:10 am
lippman.mark
(@lippman-mark)
Eminent Member
RE: Hot end dove into the bed mid-print

Not to confident the PINDA is bad. If you replaced it you also changed it's position. Mine started crashing and failing calibration after a couple years of printing. Two things, I oiled the bearing bars and adjusted the PINDA so the first layer calibration had about .700 adjustment. The biggest problem was oil on the bars.

Posted : 21/04/2020 10:43 am
lippman.mark
(@lippman-mark)
Eminent Member
RE: Hot end dove into the bed mid-print

Try oiling the bearing bars. That helped mine work much better.

Posted : 21/04/2020 10:46 am
stewartr
(@stewartr)
Eminent Member
RE: Hot end dove into the bed mid-print

Yes - well lubed rods! I usually clean and oil them regularly, but I'd forgotten that I'd not used the printer for a few weeks so they'd probably picked up some dust. After a good clean I've not seen it home x,y during a print in the last two weeks of watching it, so that probably explains the strange behaviour.

However; it does not explain the dangerous behaviour of moving back to the print position, lowering as if to resume the print and then continuing to go down. I'd like to think it would have stopped when it had melted through enough plastic to trigger the PINDA, but having witnessed what happened with the first batch of defective PINDA probes I know the power of the geared Z axis. Something might have broken. So, this still looks like a software error. Maybe losing track of its real Z position, maybe trying to 'home' Z to the base, I don't know. But it certainly knew it was in the middle of a print to go back to that position...

(BTW: That instance it was printing at about 5cm Z. It never has an issue with its initial calibration, and everything generally works fine all the time:-)

Posted : 21/04/2020 8:25 pm
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