MMU3 on MK4 Idler won't Home
I have a MK4 that I've upgraded from an MK3s+ and an MMU3 that I've upgraded from an MMU2S. After the MMU2S upgrade, I began the initialization process on the printer and it gets to the point of trying to home the idler, but fails with an Idler Won't Home error and the only option on the printer is "Retry". I've been in contact with tech support for weeks now, and at their direction have disassembled and reassembled the idler body at least twice to provide photos and videos. they seem to be totally stumped as to what's wrong.
FWIW, the idler and all the idler rollers move freely; the only resistance I feel in the idler is that of the motor. There are no defects I can find in the prints of the idler and idler body and all the parts appear to be assembled properly.
Has anyone on this forum experienced this problem? If so, what steps have you taken to solve it?
Thanks
Bill Lugg
RE: MMU3 on MK4 Idler won't Home
Just a thought. I had problems on the mmu2 with the idler being rotated(not end for end but around it's axis) too far and then it would catch and not allow to rotate properly to home. I don't remember having that when I upgraded it to the mmu3 but I paid real close attention to the picture as to which side should be up.
RE: MMU3 on MK4 Idler won't Home
Just a thought. I had problems on the mmu2 with the idler being rotated(not end for end but around it's axis) too far and then it would catch and not allow to rotate properly to home. I don't remember having that when I upgraded it to the mmu3 but I paid real close attention to the picture as to which side should be up.
This issue doesn't seem to be like that. When it tries to home it rotates back and forth a couple of times, making some rather nasty noises and then reports the error. But it rotates freely from stop to stop by hand, that's the puzzling thing.
Bill Lugg
RE: MMU3 on MK4 Idler won't Home
I´m having the exact same issue. All help articles claim that the sensitivity can be adjusted right from the error menu, but it can´t, the only option is RETRY.
I´m quite confident that this issue arises from the motor used not being within the parameters of what the firmware expects. My motor came from the first MMU which was then upgraded to MMU2 then MMU2S and finally MMU3. It differs from what is shown in most pictures. This article specificly refers to that situation and recommends changing the sensitivity, but it can´t be done from any menu, and MK4S doesn´t have an USB port anymore, so there is no way to send a custom Gcode command.
RE: MMU3 on MK4 Idler won't Home
Believe it or not, I'm still dealing with Prusa Tech support on this issue. Most recently, I've been dealing with Blas Palencia who had me remove the idler motor from the MMU and run the initialization. It still produced the Idler won't home error. From that He decided the ship me a new motor, and some new "plastic parts" (I assume a new idler and idler body). I'm waiting for them to arrive now to see if they correct the problem.
I'll let you know if I have success.
Bill Lugg
I´m having the exact same issue. All help articles claim that the sensitivity can be adjusted right from the error menu, but it can´t, the only option is RETRY.
I´m quite confident that this issue arises from the motor used not being within the parameters of what the firmware expects. My motor came from the first MMU which was then upgraded to MMU2 then MMU2S and finally MMU3. It differs from what is shown in most pictures. This article specificly refers to that situation and recommends changing the sensitivity, but it can´t be done from any menu, and MK4S doesn´t have an USB port anymore, so there is no way to send a custom Gcode command.
RE: MMU3 on MK4 Idler won't Home
@lberstein, I just received a new idler motor a few days ago. I plugged it in, but no joy - still the same problem. I got back to tech support and now they've sent me a new controller board that should be here in a couple of days. We'll see if that makes a difference. FWIW, I've been working with tech support since early July on this problem without resolution and I'm now on my third customer service rep. I wonder how many other folks are having the same problem...
Bill Lugg
RE: MMU3 on MK4 Idler won't Home
What really baffles me is that they REMOVED the option to adjust sensibility from the latest firmware. I still doubt that the allowed range would work, but it's still so odd that they did.
FYI, I had this problem before with the MMU2S on a MK2.5S. After many talks with service reps, flashing tons of firmware combinations, and sending commands through serial, I managed to get that running after setting the sensibility on a value outside of the range allowed in menus. Still, I was unable to update the printer anymore or that would break, so I finally decided to get an MK4 and upgrade the MMU2S to the MMU3, only to find not only the problem reappeared, but it got WORSE.
Please keep us updated, if replacing the controller board fixes the problem I'll try to do that for mine.
RE: MMU3 on MK4 Idler won't Home
I spent a long time today chatting with support about this issue. If it is of any help, I was assured that changing the sensibility is not required anymore in the latest firmware, that why the option was removed. However, there seems to be an issue where, if the sensibility was altered in a previous firmware, new one may fail to home. This does fit my case, as I fiddled with the sensibility adjustment so many times following previous customer rep instructions, flashing firmwares multiple times and testing different sensibility settings (this was when the board was in the MMU2S unit in my MK2S printer). The rep didn´t know a fix, but is going to contact the dev team and see if they can find a solution. Apparently this wasn´t the first case, so that gives me a bit of hope.
RE: MMU3 on MK4 Idler won't Home
Well, Prusa has thrown up their hands and now wants me to send the MMU to PrintedSolid for repair. The Controller board made no difference. I suggested the problem was actually in the MK4, but the representative assured me that was "very unlikely".
This problem only showed up after I upgraded the printer to an MK4, so I was never able to fiddle with the sensitivity values.
We'll see where it goes from here.
Bill Lugg
RE: MMU3 on MK4 Idler won't Home
I FIXED IT!
I was really sure that this was a software issue, and I had the suspicion that it had to do with previous adjustments of the sensibility that I did on the MMU2S. Apparently, even flashing the firmware keeps the old settings.
What I did was hook the MK4S to PronterFace via USB. I turned it on, turned the MMU3 on from settings, and let it fail homing. Once the "retry" screen was on, the printer is idle and able to receive serial commands. I then connected to it from Pronter face and issued an M708 A0x19 X5 command to set the sensibility back to 5 (I had previously switched it to 10 on the MK2S+MMU2S). After a reset the MMU3 was able to home perfectly and all is up and running.
This is such a simple fix, I can´t believe the option to change the sensibility is not right there on the menu instead of only being able to "RETRY".
Anyway, hope this helps others!