Extruder not moving as material switches, blob of plastic results
 
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Extruder not moving as material switches, blob of plastic results  

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jousboxx
(@jousboxx)
New Member
Extruder not moving as material switches, blob of plastic results

Hello, I recently finished adding the MMU2S to my i3 MK3.

When the printer tries to switch materials during or at the beginning of a print, the following things happen:

1) Extruder moves to lowest position (pretty much right on the print bed, where it would be for first layer)

2) Printer retracts current filament from nozzle to MMU2S.

3) MMU2S switches to new filament.

4) MMU2S pushes new filament down to extruder.

5) Extruder starts pushing out filament, but none of the axes move. A large blob of plastic builds up on the bottom of the extruder. Eventually, the extruder motor starts making a clicking sound as it continues trying to push the clogged filament. The MMU2S drive shaft also keeps going. The process continues until I manually reset the printer.

This results in filament dust building up on the bondtech gears in the extruder and MMU2S, and damage to the filament that causes further problems trying to push or retract it. I got it to successfully switch filaments once, so the first layer printed sucessfully. Everything seemed pretty much the same except that the extruder moved back and forth inside the wipe tower as the color was switched. I'm not really sure what I did differently, though.

I'm using Hatchbox ABS filament with the default ABS settings of 255C extruder temp/ 100C bed temp. I was trying to print the default lizard model with a green/transparent orange body and blue eyes. I created the GCode in Slic3r Prusa edition rather than using the premade GCode because I wanted to select the correct slots for the colors. I used 0.2mm layer height, 15% infill, brim, and a 70mm color switch wipe length.

I'm not using stealth mode, and I believe all my sensors are on/functional. Everything is properly calibrated, and it prints great with only one color. Any ideas?

Posted : 31/05/2019 10:50 pm
Oz
 Oz
(@oz)
Active Member
RE: Extruder not moving as material switches, blob of plastic results

I am having the same issues. I ran the setup wizard and everything checked fine. When trying to do the 1st layer cal is just makes a blob and I have to reset the printer to make it stop.

Main firmware 3.7.1-2266

MMU firmware 1.0.5-300

Posted : 03/06/2019 12:57 am
Roy
 Roy
(@roy)
Eminent Member
RE: Extruder not moving as material switches, blob of plastic results

Did you flash the right firmware?
The Mk3S differs from Mk3 from the sensor it is using.
If you build the MMU2S and upgraded your extruder to the Mk3S version, you also need to change the printer firmware.

Posted : 03/06/2019 10:09 am
Oz
 Oz
(@oz)
Active Member
RE: Extruder not moving as material switches, blob of plastic results

Fixed it. The IR sensor connector on the Einsy was backward. Red wire right, white wire left.

Posted : 07/06/2019 12:38 am
jousboxx
(@jousboxx)
New Member
Topic starter answered:
RE: Extruder not moving as material switches, blob of plastic results

My IR sensor is plugged in correctly, and I'm still having this problem. After flashing the MMU2S with the MMU2 firmware, it got through 13 layers of the lizard before the blob occurred. Since that print, it hasn't done more than 2. The IR sensor reads N/A in the sensor readout.

Posted : 20/06/2019 8:53 pm
Gungrav3
(@gungrav3)
Eminent Member
RE: Extruder not moving as material switches, blob of plastic results

i had the same issue. i contacted prusa and we went through a couple of checks and came to the conclusion that it was my IR Sensor. The IR sensor was faulty.

Posted : 28/06/2019 4:57 am
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