MMU3 retracts filament too far when unloading from the extruder
 
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MMU3 retracts filament too far when unloading from the extruder  

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Dave D
(@dave-d)
New Member
MMU3 retracts filament too far when unloading from the extruder

Hi, I just completed the install of my MMU3 upgrade on my MK3S+ and during initial tests, I am finding that when the MMU3 unloads the filament from the extruder, it pulls it past the Finda, completely out of the Front PTFE Holder and continues until the Bondtech gears cannot grip it anymore.  This happens during the Load Test also, it seems that whenever the filament is retracted from the extruder, it always overshoots.  However, when I choose Preload to MMU, the bondtech gears grip the filament, the Finda senses the filament and then the filament is properly retracted to the end of the PTFE tube, ready for printing.   I cannot find where you can either calibrate the length from Extruder to Finda or anything like that.  Any ideas?? 

 

The picture shows the black filament unloaded from the extruder during a load test while the red and white were loaded with 'Preload to MMU' menu command.

Thanks for your time.  Dave

Posted : 16/11/2023 3:06 am
Dave D
(@dave-d)
New Member
Topic starter answered:
RE:

I am using a third party filament buffer system but I am testing with no reverse tension on the filament.  In fact, the Idler motor runs well past the time the filament clears the gears, so it's not a gravity issue.  Also, the Bowden tube is the factory tube that was included in the upgrade kit.

This post was modified 3 months ago by Dave D
Posted : 16/11/2023 2:40 pm
Dave D
(@dave-d)
New Member
Topic starter answered:
RE: MMU3 retracts filament too far when unloading from the extruder

Solved:  FINDA sensor a tiny bit too close to the ball, was not immediately turning off.  I should have used the LED in the sensor to set it instead of just the LCD display which has a delay.   Lesson learned

Posted : 17/11/2023 6:52 pm
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