MMU3 filament loading problems
Hi there!
I got about 1 weeks worth of MMU3 printing done - mostly small test samples as I got my slicing software dialed in, octoprint configured and more. Coming from the MMU2 I was seeing it work a lot easier. And I was getting ready to do the first large multi-color print - then the last test print on the last 3 layers had issues loading the filament to the extruder. With a bit of manual guidance I got the test print to complete, decided to do another test to figure out if I could solve the load error, but alas I've run into a wall.
Filament gets to the extruder - it approaches it a bit slow - then it goes back to the FINDA, and tries again, next time it goes back it will cut the filament and try again, and the next time it tries it'll fail telling me "the filament may need to be cut".
I've gone into the "support" section under sensors and I noticed the filament sensor didn't exactly detect when the filament entered - it had to actually push on the pully gears to change the sensor. The MK3s+ has a "door" where the long thin lever is pushed into the sensor - and I've adjusted the screw to the left side of this sensor and the door, and the best I can make it is that the filament has to be gently pushed against the gear to change the sensor. But it's ultra sensitive at this setting.
If I gently hold my hand on the extruder when the filament hits it, it's like "cruncy gears" - and the filament screen looks like this. During my test print this screen had nothing but full blocks - I'm thinking it may be the IR sensor saying "it's there, it's not there" over and over again - but I'm not sure. Is that what this screen shows?
From here I feel like I'm back in the MMU2 mode - not really sure what to do. If I take the MK3S+ out of MMU mode I can load filament even with auto-detect, and print. It's only when used from the MMU3 it gives up. And it worked for a week or so (with a print a day - so not a lot of activity).
RE: MMU3 filament loading problems
I would try loosening the idler tension just a little bit and see if the number of dashes goes down.
You may need to play with a bit to get it loading to the extruder correctly.
RE:
> During my test print this screen had nothing but full blocks - I'm thinking it may be the IR sensor saying "it's there, it's not there" over and over again - but I'm not sure. Is that what this screen shows?
Yes, for a successful load you should only see full blocks, no dashes. Dash means your filament sensor reading is flickering.
RE: MMU3 filament loading problems
My wife was having the same problems. As a machinist and use to these type of problem, I look into the problems. #1 the tower had some small imperfections. I filed down the part of the chimney where the screw goes through the I/R circuit board and made it smooth. #2 I looked into the 90 degree corners opposite of were the wires go into the chimney and found filament poop. Cleaned that out. The I/R board then sat flat to the top of the chimney. #3 Insert a piece of filament into the extruder while tightening the screws to hold the tower in place. #4 Adjust the tension screw on the left side of the extruder until the it shows filament is loaded and give a quarter turn past that point. Remove the filament to see if it turns off. Insert the and remove the filament a few times to make sure the sensor is working properly. Adjust if necessary until working correct. Bottom line is that if the I/R sensor board is too high, the arm will not block all the I/R and give false readings. Look inside the side of the chimney and if there is a 2mm gap then the sensor is not low enough and to stop all the I/R from passing through to the receiver sensor.