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How to fix filament jam on MMU2S?  

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gnat
 gnat
(@gnat)
Noble Member
RE: How to fix filament jam on MMU2S?

Yeah the S seems to put the gear more into the path. If you disable the steppers it should be a bit easier to feed the filament.

I would put the door on and adjust the tensionor where you had it for the last print. Get something faster than Benchy to make sure with the hinge pin properly tightened it still prints fine with the sensor enabled.

If it does, now* add the MMU back and start with a single filament test. I wouldn't even load more than just the first tool to start.

By "now", I'd suggest that if you are going to replace your bearings as mentioned in your MK3 thread, that you go ahead and do that now before going through all the work to get the MMU working only to tear it all apart and have to start over. After swapping the bearings I would recommend doing all your calibration and testing exactly as you have the printer now (just as a MK3S without the MMU). In other words, take as many variables out of the mix as possible.

MMU tips and troubleshooting
Postato : 24/05/2019 9:51 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

One other thing I noticed: The extruder motor gets REALLY HOT while printing. Like too hot to touch. I don't recall this happening on my MK3, but maybe this is normal now?

Postato : 24/05/2019 9:53 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

IR sensor seems to be working reliably (after testing with multiple auto-loads). I'm a little concerned at the amount of force required to push the filament far enough between the bondtech and idler that the IR sensor detects it, but maybe I'm just used to the optical sensor on the MK3, where no pressure at all was required. Seems like loading it this way all the time will eventually push the print head off-axis or something.

Good point about the bearings, but I'll shelve that project for a later date (until I get the MMU working).

Postato : 24/05/2019 9:56 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

So MMU single-filament print appears to work fine (but I wasn't really expecting it to fail). Now for a two-tone print. Any suggestions?

Postato : 24/05/2019 10:20 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

Oh man, the single-filament prints look really good. I guess I was overdue for a nozzle change...

Postato : 24/05/2019 10:26 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

Okay, I'm printing this now. I noticed that every filament change seems to leave a huge blob of melted plastic in the wipe tower. I'm having to perform surgery on it with side cutters while printing.

Postato : 24/05/2019 11:12 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

Okay, not every filament change. Only on the ones that have to be retried.

Postato : 24/05/2019 11:15 pm
gnat
 gnat
(@gnat)
Noble Member
RE: How to fix filament jam on MMU2S?
Posted by: phil.d8

IR sensor seems to be working reliably (after testing with multiple auto-loads). I'm a little concerned at the amount of force required to push the filament far enough between the bondtech and idler that the IR sensor detects it, but maybe I'm just used to the optical sensor on the MK3, where no pressure at all was required. Seems like loading it this way all the time will eventually push the print head off-axis or something.

Good point about the bearings, but I'll shelve that project for a later date (until I get the MMU working).

When I changed the door inserting filament became as easy as it was before I upgraded. Might still be worth a look for you. 

The harder it has to work to get the filament through, the hotter the motor will be. So reducing that pressure will likely bring the motor temp down some. 

MMU tips and troubleshooting
Postato : 24/05/2019 11:16 pm
gnat
 gnat
(@gnat)
Noble Member
RE: How to fix filament jam on MMU2S?
Posted by: phil.d8

Oh man, the single-filament prints look really good. I guess I was overdue for a nozzle change...

A chunk of that is probably due to the work you've done. I'll continue to recommend the pre-built printer as a starting place, but once I started understanding things I saw how sloppy their job was. Now my .2mm prints look as good (when looking at layers) as .1 prints used to. 

As far as your blobbing, I haven't seen that. 

MMU tips and troubleshooting
Postato : 24/05/2019 11:20 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

During this print, I left the LCD menu on sensor info. It looks like the IR sensor is flapping between zero and one during printing. So a feed will succeed or fail from the MMU based on luck of the draw, more or less.

 

So I guess I need to go calibrate the IR sensor. again.

Postato : 24/05/2019 11:21 pm
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

Welp, I'm about 80% of my way through the 2-color print, and filament changes are succeeding more often than they're failing. A half-dozen retries so far over the course of the print, with only one needing manual intervention (trimming the filament end, when it didn't ram properly and got a blob on the end).

Overall, I have no idea what I did, other than remove and reassemble the idler door, but it's an improvement!

Next:

  • Print a new idler door (thanks gnat!)
  • Print auto-retracting spool holders, so this thing doesn't take up my entire workbench.
  • Print 3/4/5 material prints.
  • Hope my extruder motor doesn't burst into flames.
Postato : 25/05/2019 12:49 am
roach374
(@roach374)
Eminent Member
Topic starter answered:
RE: How to fix filament jam on MMU2S?

Aaaand now I'm having first-layer problems. The fun never ends.

Postato : 25/05/2019 5:18 am
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