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MMU2S nothing but problems  

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MMU2S nothing but problems

I have had nothing but problems with my MMU2S since i put it together. I have been able to print a single multi colored item and only a few sigle color. First it was the IR sensor now it refuses to load any filament


My persistent issue is that the filament has no problem unload from the nozzle but never actually run a complete load



i have calibrated the ir sensor severla time but the filament never travels down the ptfe tum from mmu to print head

Posted : 30/03/2020 11:20 pm
RE: MMU2S nothing but problems

I indeed had the same issues, they lasted over two months, now it purrs like a kitten.

My problem originated from a warped idler, it doesn't take much to cause problems. Akin to a car that is out of alignment, the bearings don't hit the filament over the gears causing nothing but problems. I tried all that tech support could tell me. Checked wiring and other efforts. The mmu should be able to push or pull practically any filament ends through the ptfe going to the extruder. I took the finda probe off after replacing the idler and started the filament in any of the channels and the mmu almost pulls the printer over. I believe that is what you should have.

If the idler is the problem you can verify that it is warped by simply opening up the mmu with the unit turned off or the steppers turned off rotate the idler by hand. Looking at the left idler body, alongside of the motor you should see no flexing at all. If there is movement then you may have a warped idler. Also, the screws that keep the pins on the body in place should not be overtightened, loose just touching the surface. I wish that I had made a video when I had a problem. I suspect that the idler, being petg, could warp a little during the manufacture and pass quality control because of small differences. Any minor twist on a long barreled idler is exaggerated at the motor, or could be the other side of the idler. Just look for any movement. I believe that if you loosen the screws on the idler motor you could see more movement. This was my case and your symptoms indeed look similar.

Good luck,


Stay safe and healthy, Phil

Posted : 31/03/2020 3:12 pm