paul.m27
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Joined: Sep 23, 2017 5:47 pm
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Idler broke while loading filament for the first time

Sep 16, 2018 2:45 pm

I was going through preflight check and my first filament wasn't loading cleanly. I swung open the MMU2 and adjusted the pulley position, and didn't notice any problem. Next time I pushed the filament in, it came out the front of the MMU2. Looking in, I noticed that the 2nd idler bearing was over it's pulley, rather than the left most. Opened up to debug and noticed this:

Image

I guess I'll be trying to get my printer working as a single color printer now so I can reprint the parts!

Is there a way to get the Mk3 to ignore the MMU2? Just unplug the signal wire?

paul.m27
Posts: 282
Joined: Sep 23, 2017 5:47 pm
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Re: Idler broke while loading filament for the first time

Sep 16, 2018 3:08 pm

Closeup of the failure now that I have it extracted:

Image

On the positive side, I can dial in my extruder upgrade without worrying about the MMU2, and then bring all the MMU2 issues in with a stable base platform.

[update] Since I've got the new extruder and new firmware now, I did a factory reset and recalibrated. MMU2 power/signal cables disconnected, idler open, just feeding filament from the back through the MMU2 selector/PTFE. Seems to work fine as a normal MK3.

Calibration and PLA print went fine. Did a PID calibration and then printed a black PETG calibration cube.

I'm now printing a new idler in black PETG, 3 perimeters/40% grid infill. I think recommended is 2 perimeters/20% infill, so I'm sure I'm going to regret my paranoid overkill when it turns out the recommendations were there for a reason.

I had to get medieval on the original idler to get the hardware back:

Image

The real question I need to figure out before I reassemble: what did I do wrong that caused the original idler to self destruct?

khalil.n
Posts: 77
Joined: May 07, 2017 5:24 am
Location: Brooklyn NY
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Re: Idler broke while loading filament for the first time

Sep 17, 2018 1:16 pm

I can't say 4 certain why yours broke on your 1st print.
But I can say mine looked exactly like your photo after I over torqued the screws that attached the idler body to driver shaft.....
Luckily had another mk3, just printed another one. Was a pain getting the hardware out.

paul.m27
Posts: 282
Joined: Sep 23, 2017 5:47 pm
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Re: Idler broke while loading filament for the first time

Sep 17, 2018 4:07 pm

khalil.n wrote:
Sep 17, 2018 1:16 pm
I can't say 4 certain why yours broke on your 1st print.
But I can say mine looked exactly like your photo after I over torqued the screws that attached the idler body to driver shaft.....
Luckily had another mk3, just printed another one. Was a pain getting the hardware out.
Quite possible I overtorqued. I am usually pretty good on 'monkey strong' not 'gorilla strong', but who knows, it was late at night. Even if I didn't crack it, I could have weakened it and it cracked later.

I've already printed a new one, as even the MMU2 Mk3 works just fine as a plain mk3 if you just unplug the MMU2 wires. My only delay was that I'd rebuilt the extruder and needed to go through calibration. Looking good so far. 3 perimeters, 40%, so slightly sturdier.

Image

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