MK2S MMU Attempting to drive past endstop  

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ty.b
 ty.b
(@ty-b)
Eminent Member

My Prusa MK2S MMU appears to be attempting to drive through the X-endstop while trying to autohome (The endstop on the left side, mounted to the Z-axis gantry). The system detects the endstop during the self-test. The endstop appears to function normally using a multi-meter. The wiring appears sound.

When the system is trying to drive the head to 0,0,0, but is attempting to move it past the endstop, even if I manually trigger the endstop, it continues to turn the motor (resulting in a grinding sound).  I have to hit the reset button to get the system to stop.

(Quick edit: hit update too early)

I have updated the firmware. I have rechecked alignment, and tightened screws.  As stated above, I've checked the function of the switch.  I've used this printer for a couple of years.  I've built several printers before, including one completely custom one.  I can't figure this one out.

Any thoughts?  Thanks in advance.

This topic was modified 2 years ago by ty.b
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Posted : 23/07/2019 6:27 pm
Dave Avery
(@dave-avery)
Honorable Member

wrong firmware, double check the printer version when you download the firmware

Posted : 23/07/2019 6:52 pm
ty.b
 ty.b
(@ty-b)
Eminent Member
Posted by: david.a66

wrong firmware, double check the printer version when you download the firmware

Thanks for the fast reply!

I used the right firmware (MK2/S Multimaterial 1.0, Firmware 3.2.3, Rambo 1.3 as my display ports are on the board).  I reflashed it while writing this, and retried the Selftest.

No problem with the X endstop (Or any of them). The Selftest seems to run without issue, until it tries to autohome at the end, and then it grinds.

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Posted : 23/07/2019 7:06 pm
ty.b
 ty.b
(@ty-b)
Eminent Member

I don't know if this helps, but when the system is performing an autohome (G28 W), it actually moves to the x/y 0 position, bumps the x endstop, rebounds slightly under drive, and then drives into the endstop again in a grinding fashion.  It very much seems to be two different movements.

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Posted : 24/07/2019 9:18 pm
ty.b
 ty.b
(@ty-b)
Eminent Member

Anyone else have any other thoughts besides "bad firmware"?

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Posted : 29/07/2019 2:18 am
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 --
(@)
Illustrious Member

Limit switches do fail ... 

Posted : 29/07/2019 9:00 am
ty.b
 ty.b
(@ty-b)
Eminent Member
Posted by: Tim

Limit switches do fail ... 

I know! That's the strange thing.  The switch tests out as working during the self test.  The switch appears to trigger during the initial homing sequence.

I'm going to take video when I get today.  A five second video will fill in a lot of gaps.

Thanks for replying!

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Posted : 29/07/2019 3:59 pm
ty.b
 ty.b
(@ty-b)
Eminent Member

https://photos.google.com/share/AF1QipNWC8oCP6Cv4haIZLo-iUXLZo8Uk3-QJosRAUtqdAKXg4q03snyzzkgDoStXf6N_w?key=QWJRcDhrRHFZZXpZeVl6ejZ6dWVua25PSkhmMjNB

If you take a look at the video, it's reporting that the Self Test is OK.  However, during the auto  home routine it is acting like the endstop is not there.  In the video you can (sort of) see me directly pressing the endstop switch, with no luck.  

This seems to be a consistent failure, only at this point (auto homing).

I've reflashed the firmware, I've checked connections, I've tested the switch itself. This seems to be a completely normal printer, until it goes to auto home.

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Posted : 06/08/2019 2:34 pm
Nikolai
(@nikolai)
Noble Member

Hi ty-b,

It's actually easy to test. Connect the printer to Raspi or PC. Run "G28 W" command. Hit the x-limit switch. Printer should recognize that and stop the movement in x direction.

If it does not work, the failure path would be:

  1. Switch itself
  2. Wire to the switch
  3. Firmware
  4. Board
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Posted : 06/08/2019 5:52 pm
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