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IDLER can't home  

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danman
(@danman)
Active Member
IDLER can't home

Hi all,

I purchased an upgrade from MMU2 to MMU3 for my MK3S+ printer. After I finished building the MMU I got the message "Idler cannot home".

I rebuilt the MMU from scratch. Same result.

I changed the motors and the MMU control board - the same result.

I upgraded the firmware to version 3.13.2 for the printer and 3.0.1 for the MMU - Same result.

I tried to change the sensitivity (StallGuard) from the default 7 to 4 or even 9 (using the M708 command) - nothing changed.

Can someone help me with this issue?

Thank you in advance.

Posted : 28/11/2023 9:19 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE:

Hi Danman, 
If you unscrew the idler tension screws, completely, can the idler home? 

If the idler tension screws are too tight, it will stop the idler homing. 

when the printer is off, can you turn the idler drum, by hand easily? 
there are 5 idler rollers in the drum, each idler roller presses against the filament and pulley when in the correct position, if there is too much friction the idler drum will not rotate properly.

one of my motors needed a small spacer... possible because they were re purposed MMU1 motors... I will try and remember to have a look when I go tot he workshop later, and see which it was... 

Apart from the spacer, I assembled my MMU3 according to the assembly guide, and it worked first time. 

If you still have issues, some pictures may help. can you add some pictures from different angles please... 

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 28/11/2023 10:09 pm
danman
(@danman)
Active Member
Topic starter answered:
RE:

Hi Joan,

No, even with the completely free idler it is the same behavior.

As I said before, I redid the MMU construction from scratch.

I'm quite upset because I really needed to make some parts using MMU.

I have attached two videos with the behavior of the printer with MMU.

https://storage.googleapis.com/prusa3d-content-prod-14e8-wordpress-forum-prod/2023/11/0f6dffe0-asembled-1.mp4

https://storage.googleapis.com/prusa3d-content-prod-14e8-wordpress-forum-prod/2023/11/4ab87c99-with-the-idler-completey-free-2.mp4

Thank you.

Posted : 29/11/2023 10:29 am
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: IDLER can't home

Is the drum rubbing in the housing or the motor at either end?

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 29/11/2023 4:35 pm
danman
(@danman)
Active Member
Topic starter answered:
RE: IDLER can't home

Neither one. 

The rattling that is heard is caused by the idler hitting the limiter at the end of the stroke. What I don't understand is why the MMU controller doesn't accept this end and doesn't check the other end as well.

Best Regards,

Dan

Posted : 30/11/2023 9:01 am
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: IDLER can't home

That is a question I Cannot answer...
If you remove the motor and disconnect the idler drum. does the motor turn smoothly. 
My Pulley motor (used to be an extruder motor on the MMU1, Ian I shortened the wires) broke one wire off the plug, and that just trembled instead of moving properly...

Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 30/11/2023 12:24 pm
danman
(@danman)
Active Member
Topic starter answered:
RE: IDLER can't home

Hi Joan,

Yes, the Idler Motor spins freely (without the Idler body) for 2 revolutions, then stops, tries again for one or two revolutions, stops again and after the third attempt, the printer starts signaling that the idler cannot home.

I redid the MMU assembly from scratch (twice).

So far I replaced the MMU controller, motors (all 3).  From a discussion on the forum, I understood that it could be a power supply problem, so I also changed the 24V power supply (before I had the old white power supply and now I have a black one). The only thing I can't replace (yet!) is the controller daughter board and the power and signal cable to the printer controller.

Posted : 30/11/2023 3:21 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: IDLER can't home

I am using the old silver power supply. And the ruby power board

Your issue is perplexing.

When the motor turns. Can you stop the shaft easily?

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 30/11/2023 7:32 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: IDLER can't home

Maybe this thread will help you. Otherwise, I would contact the Prusa team (Prusachat).

wbr,

Karl

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

Posted : 30/11/2023 10:15 pm
danman
(@danman)
Active Member
Topic starter answered:
RE: IDLER can't home

 

Posted by: @joantabb

I am using the old silver power supply. And the ruby power board

Your issue is perplexing.

When the motor turns. Can you stop the shaft easily?

No, I tried but it is not easy to stop the idler motor

B.R.

Posted : 01/12/2023 4:30 pm
danman
(@danman)
Active Member
Topic starter answered:
RE: IDLER can't home

 

Posted by: @karl-herbert

Maybe this thread will help you. Otherwise, I would contact the Prusa team (Prusachat).

wbr,

Karl

Hi Karl,

I read the whole thread carefully. I tried using the Arduino IDE to send M707 to read and M708 to write to the MMU registers. I have not received any response. I'm probably doing something wrong. I will try again tomorrow with PuTTy. I hope to have more success. I also spoke with technical support from PRUSA. On their advice, I sent an email to the attention of the MMU team. I hope they will help me with a solution to my problem. I have two MMU units both with the same problem, so I tend to think that the problem is not mechanical but electronic or software. All motors in the two MMUs are genuine PRUSA. I guess that probably is somwhere in the daughterboard of the controller.

Best Regards

Dan

Posted : 01/12/2023 4:59 pm
Hello
(@hello)
Noble Member
RE: IDLER can't home

 

Posted by: @danman

 

Posted by: @karl-herbert

Maybe this thread will help you. Otherwise, I would contact the Prusa team (Prusachat).

wbr,

Karl

Hi Karl,

I read the whole thread carefully. I tried using the Arduino IDE to send M707 to read and M708 to write to the MMU registers. I have not received any response. I'm probably doing something wrong. I will try again tomorrow with PuTTy. I hope to have more success. I also spoke with technical support from PRUSA. On their advice, I sent an email to the attention of the MMU team. I hope they will help me with a solution to my problem. I have two MMU units both with the same problem, so I tend to think that the problem is not mechanical but electronic or software. All motors in the two MMUs are genuine PRUSA. I guess that probably is somwhere in the daughterboard of the controller.

Best Regards

Dan

It's a know issue in the mmu2 using mmu3 firmware install this firmware https://github.com/prusa3d/Prusa-Firmware/releases/tag/v3.13.2

Then on the error screen click tune then change the values till it works.

Please help me out by downloading a model it's free and easy but really helps me out https://www.printables.com/@Hello_474427/models

Posted : 01/12/2023 6:34 pm
Codeplayer
(@codeplayer-2)
Active Member
RE: IDLER can't home

You should set the sensitivity to 10 if you run 12V system with the M708 command. This worked for me on MK2.5S+ and MMU3.

Posted : 21/01/2024 8:02 am
zukpr
(@zukpr)
Eminent Member
RE: IDLER can't home

I built the MMU3 from a kit (not an upgrade from MMU2).  I had this problem as well.  The idler couldn’t home.  For me it was a matter of adjusting the idler screws and tuning the sensitivity as @home indicated.  I was able to get it working that way.

Posted : 22/01/2024 1:13 am
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