Filament enters extruder but doesn't reach Bondtech Gears
 

Filament enters extruder but doesn't reach Bondtech Gears  

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matthew.kaul
(@matthew-kaul)
New Member

Hello,

I recently finished assembling my MMU2S upgrade on my i3 Mk3 (now Mk3S). After resolving issues with the idler tension, the filament can successfully change and enters the PTFE tube to the extruder. It reaches the extruder body and trips the IR sensor, which I have calibrated many times, then fails to reach the bontech gears. The extruder motor then spins very fast but the filament just doesn't quite go far enough. I believe this is either a result of the IR sensor being tripped too early and causing the pulley motor to stop or is caused by too much friction in the extruder which feels more realistic given the filament is getting eaten away at in the MMU2S unit and there feels like a great deal of friction when I remove the Festo and try to put filament in. If anyone has any potential solutions your help will be greatly appreciated. 

Posted : 13/06/2019 11:45 pm
david.a66
(@david-a66)
Honorable Member

on the MMU2s the IR sensor at the extruder should only be tripped when the filament is in the bondtech gears. the IR sensor is monitoring the bondtech idler door position. make sure you have the non-ball bearing adapter in the extruder and the chimney with the long arm idler door. you should be able to test the IR sensor from the front panel and see it go from 0 to 1 as the filament moves the idler door. you can test with teh mmu2 tube diconnected from the extruder and hand feeding the filament into the extruder

Posted : 14/06/2019 12:14 am
matthew.kaul
(@matthew-kaul)
New Member

Thanks for the advice. Turns out it was an issue with the IR sensor at all and I just had to tighten up the tension on idle gear to get it moving. 

Posted : 14/06/2019 1:12 am
markus.t
(@markus-t)
New Member

It seems that I have a similar problem with my newly assembled MMU2s. The filament is pushed all the way to the extruder but then it is not picked up the Bond-Tech gear. I calibarted the IR-sensor a couple of times. What I am not sure about is the strength one needs to push the allan key (1,5 for calibration purposes) down. In my case one needs some force to get the alan key into the bond gear. So I played around a little bit with the tension of the idle gear.

One other thing I noticed, when I am trying to calibrate the Z-axis, after selecting the PLA, the filament is pushed to the extruder, but just before starting to print, the filament is pulled back again. That seems to be weird, since the test print is starting.

Maybe someone has a hint where I made a mistake or where I should do further ckecks. I have the latest firmwar flashed to the MMU and printer itself

Thanks, Markus.

Posted : 02/07/2019 9:38 am
markus.t
(@markus-t)
New Member

well, I did some more analysis. It seems that I am having a different problem. I unassembled the extruder-idler-mmu2 (step 32. https://manual.prusa3d.com/Guide/3A.+MK3-MK2.5+-+extruder+upgrade/1069?lang=en) and the filament did reach the Bondtech gears.

I guess, there is something blocking within the hotend so that the Bondtech gear is not possible to push the filament through the hotend.

Posted : 02/07/2019 10:08 am
john.w55
(@john-w55)
New Member
Posted by: @markus-t

well, I did some more analysis. It seems that I am having a different problem. I unassembled the extruder-idler-mmu2 (step 32. https://manual.prusa3d.com/Guide/3A.+MK3-MK2.5+-+extruder+upgrade/1069?lang=en) and the filament did reach the Bondtech gears.

I guess, there is something blocking within the hotend so that the Bondtech gear is not possible to push the filament through the hotend.

Sorry for pulling up this old thread, but it looks to me like I also have something blocking the hotend and the filament cant get in there. @markus-t What did you do to solve this?

Posted : 29/10/2019 6:10 pm
sebastian.h10
(@sebastian-h10)
Active Member

I remotely remember this problem. Never happened again when I changed to a version with path-through and after properly calibrating the IR sensor.

https://www.thingiverse.com/thing:3467644

https://www.thingiverse.com/thing:3850541

Posted : 29/10/2019 9:32 pm
markus.t
(@markus-t)
New Member

@john-w55

actually no, did not had the time to experient more with the mmu. I removed the mmu 🙁

Posted : 30/10/2019 8:09 am
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