Extruder Clicking during longer prints  

Re: Extruder Clicking during longer prints

Jamming at the Bondtech gears during retractions can be caused by too many cooling moves. The tip expands slightly as it cools, and if it gets too cool, the tip will be too big and too hard to fit back up through the Bondtech gears.

Don't use the sample .gcode that Prusa shipped. I think they were using 4 cooling moves. Instead, take the original objects (they are installed by the Prusa drivers package into your Public Documents folder) and re-slice them using a better profile. If you're on the Prusa community group on Facebook, get Chris Warcocki's MMU Pretty V1.2 profile. Or you can try the settings that TheZeroBeast posted here:

Re: Extruder Clicking during longer prints

thanks for the feedback. I was using 4 cooling moves and went back to generic Prusament settings of 1 but still no luck. Did make things better but filament was still sticking.
Been struggling with this since getting the MMU2 two weeks ago. What I think I found today is that I had an incompatible heatbrake. The one I had had a smaller diameter at the hot end that stopped the head of the filament right at the cold end of the narrow part of the brake. I found one that had same diameter throughout and have successfully printed my own sliced Prusa models most of this day.
Slic3r Settings that seem to be working are printer settings, single extruder MM setup, cooling tube position 20 and cooling tube length 10. I am using Prusament at the moment as I wanted to minimize any influences. Filament settings, are generic Prusament with the exception of ramming set to 2.0.
I had "upgraded" to the E3D gold extruder and it was working great for single color prints but should have learned to go back to stock before the upgrade....

Re: Extruder Clicking during longer prints

thanks for the feedback. I was using 4 cooling moves and went back to generic Prusament settings of 1 but still no luck. Did make things better but filament was still sticking.
Been struggling with this since getting the MMU2 two weeks ago. What I think I found today is that I had an incompatible heatbrake. The one I had had a smaller diameter at the hot end that stopped the head of the filament right at the cold end of the narrow part of the brake. I found one that had same diameter throughout and have successfully printed my own sliced Prusa models most of this day.
Slic3r Settings that seem to be working are printer settings, single extruder MM setup, cooling tube position 20 and cooling tube length 10. I am using Prusament at the moment as I wanted to minimize any influences. Filament settings, are generic Prusament with the exception of ramming set to 2.0.
I had "upgraded" to the E3D gold extruder and it was working great for single color prints but should have learned to go back to stock before the upgrade....

I have been having the same issue for a month now, driving me BONKERS!!! I read a post on reddit a few days back that said the E3D heatbreak is different than the Prusa one. I had replaced mine a while back after a nasty jam. I ordered the prusa specific heatbreak a few days ago, really hoping this fixes my problems. So if I'm understanding correctly, the stock prusa specific heatbreak seemed to fix your problems?

Re: Extruder Clicking during longer prints

Yes, Stock Prusa heatbrake is working wonders. I have been continuously printing multicolored items since changing the heatbrake with no intervention on my part. I was sooo close to taking the MMU2 off out of frustration. What I keep coming back to was the filamanet head formed during retract was bigger than the heat brake diameter at the hot end. The smaller diameter starts right at the top of the narrow section so is cooled more than the hot side of the narrows and the filament would jam there all the time. I have been using the printer settings single extruder mm setup cooling tube position and cooling tube length to do the cooling inside of the cool end of the heatbrake. I have no idea if this is the right thing to do or not but several days of non stopped printing have said it is good enough.

Re: Extruder Clicking during longer prints

Yes, Stock Prusa heatbrake is working wonders. I have been continuously printing multicolored items since changing the heatbrake with no intervention on my part. I was sooo close to taking the MMU2 off out of frustration. What I keep coming back to was the filamanet head formed during retract was bigger than the heat brake diameter at the hot end. The smaller diameter starts right at the top of the narrow section so is cooled more than the hot side of the narrows and the filament would jam there all the time. I have been using the printer settings single extruder mm setup cooling tube position and cooling tube length to do the cooling inside of the cool end of the heatbrake. I have no idea if this is the right thing to do or not but several days of non stopped printing have said it is good enough.

Thanks! I can't wait for the part to arrive! Do you mind posting a screenshot of your filament settings?

Re: Extruder Clicking during longer prints

In the end after getting things running the only setting that was changed for me is in the printer settings. I tried lots of things but they all failed. For filament I used Prusament settings and Prusament filament trying to eliminate as much as I could. I haven't started testing too many filaments after gettings things working. I have tried Protopasta at the same Prusament settings and it seems to be working well.
for printer settings I went to
Single extruder MM setup
First I changed the Cooling Tube Position setting to 20 which is the distance I measured from the tip of my nozzle to the cold end of the narrow part of the heat brake.
I then changed Cooling Tube Length to 10 which was the measured distance from the top (cold end) of the narrow section of heat brake to the start of the Teflon tube. My logic is that the maximum cooling should happen where the filament is in contact with the heatbrake metal not using the Teflon tube area. I have been printing MM things for days now and no user intervention is needed anymore.
I also ordered spare heat brakes and Teflon tubing from Prusa to have on hand.
Hope you can have similar success. I know I really felt relief to solve this one on my end. I know your frustration.