MMU2 Filament Motor Doesn't Turn During Print.  

RE: MMU2 Filament Motor Doesn't Turn During Print.

Posted by: sfshook22

the extruder motor feeds but the MMU2 motor doesn't feed and therefore no print.

The prints you are trying to do from the SD card, are they sliced for the MMU in either single or multi-filament mode? If not, then what you are experiencing is normal as there is nothing in the gcode to tell it to have the MMU do anything.

If you are using a file sliced for the MMU, is the drive motor on the MMU actually turning (look in and see if the gears are moving)? If so, did the idler move? Did it move to the wrong position (e.g. say to tool 2 while the selector is at tool 1)?

If you are using a MMU sliced file, the first step I'd take is to reset the MMU (tiny button next to the USB port) and see if that helps. If that doesn't help, then some more info about how the various parts of the MMU (selector position, drive motor, idler movement/position) might be helpful.

RE: MMU2 Filament Motor Doesn't Turn During Print.

Gnat,

The reset seemed to work. Not sure why I needed to do that from one print to the next. But will keep an eye on it to see if I have to do that for the next print.

Thank you again for all the help,

Steve

RE: MMU2 Filament Motor Doesn't Turn During Print.

The reset is my go to option when it does something weird. You can even use it mid print if needed without having to cancel the whole print (if the reset fixes the issue anyway).

As far as the why, based on my experience and what I've seen from others it appears that the MMU loses it's mind from time to time and the idler and selector get out of sync. I haven't seen any explanation as to why it happens though. Luckily the reset seems to almost always fix it.

RE: MMU2 Filament Motor Doesn't Turn During Print.

Gnat,

I found a work around that works for me. After turning on the printer, I do a reset of the MMU2s and then proceed to print from the SD card.

I have no idea why it works, but it does. If I don't do the reset then the filament is loaded, but doesn't continue to pass through the MMU the stepper motor doesn't turn.

My work around works on single filament prints and multiple filament prints. I seem to only have to do the reset after starting up the first time. I can print multiple items one after another from then on.

Again I have no idea why this works and you may have some idea.

Again thank you for all of your help,

Steve

RE: MMU2 Filament Motor Doesn't Turn During Print.

during print the MMU should be disengaged from the filament. as soon as the filament hits the IR sensor on the extruder , the extruder bondtech gear grabs the filament and the indexer in the MMU rotates a bit so the bearing is no longer pressing on the MMU bondtech gear and the filament is free to move

RE: MMU2 Filament Motor Doesn't Turn During Print.

1. That means the mmu isn't releasing the filament when it should as bondtech gear does grind a notch in the filament unless the stepper motor is turning.
2. Not sure how to fit that.

RE: MMU2 Filament Motor Doesn't Turn During Print.

I had many undefinable problems or error messages whenever the full file path on the SD card is too long.
Thereby, e.g. Error like "min temp error".
In one case, the MMU Stepper Motor ran simultaneously with the extruder Stepper Motor.
Unfortunately in opposite directions ....
I then took the file and moved to a folder directly on the SD card (root).
Now the print came out without problems.
Many problems (at least for me) seem to be related to a too long full memory path.
I avoid them now and everything is good.
Maybe it is related to the good old "256 characters limit".

RE: MMU2 Filament Motor Doesn't Turn During Print.

My files are in the root directory. I will try shorting the names to a minimum length.

RE: MMU2 Filament Motor Doesn't Turn During Print.

If they are in root, then they should not cause the problems.
Mine (that failed) hat more then 270 characters in the complete path.

RE: MMU2 Filament Motor Doesn't Turn During Print.

Do you use any "control characters" in your filename?

RE: MMU2 Filament Motor Doesn't Turn During Print.

No control characters just alpha numeric characters.

Here is an example of the file name before: 5-20x20x3_TestSquare_0.15mm_PLA_MK3SMMU2S_10m.gcode

After shortening: 5-20x20x3_TestSquare_PLA.gcode

RE: MMU2 Filament Motor Doesn't Turn During Print.

Hmm, that should be fine.
What about the Hardware? Did you doublecheck everything?
Does the MMU Stepper move? Maybe it is the grub screw that came loose?
Did you already install the latest Firmware?
Did you calibrate the MMU? 
But this is all just poking in the dark.

RE: MMU2 Filament Motor Doesn't Turn During Print.

david-a66,

The mmu doesn't disengage from the filament during the print cycle. It stays engaged and the stepper-motor doesn't turn thus the filament doesn't move through the extruder. If I perform the reset then the stepper-motor feeds the filament in to the gears as they turn and it works. 

Still not sure what could be wrong, but this work around works and I have no idea why.

Thank you,

Steve

RE: MMU2 Filament Motor Doesn't Turn During Print.

kai-r3,

The I check all the hardware including making sure that the selector motor was correctly position the marks on the shaft confirmed that.

The stepper motor moves and feeds the filament in the loading phase. I moves during the print phase if I performed the reset in the correct sequence.

I installed the latest firmware released yesterday. Works the same as the previous version.

I calibrated the mmu.

Again I have no idea what could be wrong and I don't know why my work around works, but it does.

Using the work around I haven't had a print failure caused by the printer or the mmu for single or multiple colored prints.

Thank you,

Steve

RE: MMU2 Filament Motor Doesn't Turn During Print.

hook up pronterface ( or any other terminal program) to the EINSY USB port and  you can see the outputs from the MMU as it works