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[Solved] Loading to extruder  

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Ed
 Ed
(@ed-5)
Active Member
Loading to extruder

Hi

I've been having a very frustrating time with my recently assembled mmu2s on my mk3s+.

The filament loads to MMU and sends to extruder, but it is unable to be grabbed by the extruder bondtech. I ran my unmodified mk3s for months without issue.

I have: calibrated the Finda multiple times and reduced the tension on the spring/screw to the point that one more turn disconnects the two, (the axis screw is also incredibly lose) but still the extruder cannot grip the filament.

I have unassembled the chimney and door and filed them smooth.

The IR sensor tips and recognises that there is filament and the extruder moves in the printing pattern but it will not extrude. 

The only success I have had is in completely removing the tibe, putting the filament in the extruder myself and pushing down... Hard... Until the bondtech grips, but this is my only success (at least it tells me that the extruder is properly assembled.

Any ideas?

Through all this issues I have also torn up a tonne of filament on my filament 1, had to disassemble the MMU to clean the gears... Now that won't load! but still the least of my problems at the moment! 😅

Sooo frustrating. Whats worse, is I have built it into my enclosure, so any troubleshooting is twice as painful! It's genuinely driving me mad. Anything else I can try? I don't want to give up on my $300

Posted : 12/10/2021 8:33 am
Rick Houlihan
(@rick-houlihan)
Active Member
RE: Loading to extruder

Pretty sure on my I3MK3S+ the IR sensor does not tip unless the filament is actually in the gears.  To test it I had to actually force the small hex key wrench down into the gear to make the idler assembly tilt and trip the IR sensor.  If your IR sensor is calibrated correctly then something else is wrong...you should not have to push down that hard to get the filament in...did you overtighten the idler screw on the side of the extruder? That should have a spring on it and not be cranked down.  Other than that try to find what is restricting the filament and making you push so hard for it to engage.  You should not have to apply excessive force to feed the filament manually.

Posted : 13/10/2021 1:49 am
Ed
 Ed
(@ed-5)
Active Member
Topic starter answered:
re

I have done the hex calibration, don't like shoving metal in there but has been alright and have loosened the screw to the point of it not really doing much, but still the gears are pretty hard to separate then calibrating.

Do you know if the MMU feeder turns off when the IR is tripped?

I m thinking now that maybe it has been so softly calibrated from my previous problems that while it tips the IR sensor the MMU has not actually pushed the filament far enough to properly engage the gears in the extruder. 🤔 

Do you know if the MMU feeder turns off when the IR is tripped?

Thanks for your reply

Posted : 13/10/2021 4:16 am
Ed
 Ed
(@ed-5)
Active Member
Topic starter answered:
re

Sooo lost my reply 😅 but anyway will summerise.

I have recalibrated the idler, but still it's very hard to push the filament through. The screw pin is still hanging on a thread. From reviewing the official prusa guide on this my hex key is quite a bit further up on their example, maybe stopping earlier? Are they using the standard long 1.5 key? Could it be stopped on something earlier?

I have checked the length of filament from the MMU it pushes approx 2.5 into the extruder but still doesn't trip the sensor. Even with a push it doesn't seem to move the filament as it did direct. Could it be the gears are clogged? I reeaaally don't want to have to rebuild the extruder. My printer is embedded in the enclosure so moving it out is a pain in the arse disconnecting the PSU etc.

On review of my 'pressed in filament' it still didn't pay out a good first layer. Not sure if thats just my z height setting.. though have honed it in to roughly what worked with the unmodified 3mks+ - am I wrong assuming they would be roughly the same?

Thanks for any attempts to help. 🙂

 

 

Posted : 13/10/2021 9:04 am
Rick Houlihan
(@rick-houlihan)
Active Member
re

The MMU will stop pushing when the IR sensor is tripped.  It sounds like something in the extruder is blocking the filament and the MMU cannot push past it so it starts grinding. You need to clear the filament path in the extruder. When manually feeding filament into the extruder you should only have to push lightly to get the idler to engage. Have you checked the IR sensor status in the support screen when the MMU is pushing the filament? If it changes from 0 to 1 and the MMU is still pushing then there is a problem with the handshake between the MMU and the I3MK3S, maybe check to see if the connecting cable got crimped but I would think that would disable all functions. If the IR sensor is correctly calibrated but stays at 0 when the MMU is pushing filament then the filament path in the extruder is definitely blocked.

Everything you are describing is indicating the the extruder assembly is restricting the path of the filament somehow.  I would walk back through the extruder disassembly and upgrade instructions and carefully examine each step.  When I did my upgrade I had to rotate the printer several times to get clear access to the parts that I needed to work on.  I would definitely remove the printer from the enclosure if it is restricting your ability to work on the extruder assembly from any angle.

Posted : 13/10/2021 12:43 pm
Ed
 Ed
(@ed-5)
Active Member
Topic starter answered:
Shifty

Thanks Rick. 

I took another look today, with the idler door off to see if there was anything getting in the way, and noticed... That my gear wasnt tight on the motor shaft! It just moved back and forth which would explain why there was no traction and why it would have been difficult to push the filament/hex screw in for testing.l as It wouldn't have aligned. 

Will have to do a bit of work to tighten it up, rotating the shaft in the extruder is a challenge. But hopefully this will solve the issue! Will report back.

Posted : 15/10/2021 5:36 am
Rick Houlihan
(@rick-houlihan)
Active Member
RE: Shifty

Awesome. Good to hear you have a root cause now. Hopefully the road will be less bumpy from here on out.  Also if you have not watched this video on MMU operation it might save you some frustration when you get it all working.

Posted by: @ed-5

Thanks Rick. 

I took another look today, with the idler door off to see if there was anything getting in the way, and noticed... That my gear wasnt tight on the motor shaft! It just moved back and forth which would explain why there was no traction and why it would have been difficult to push the filament/hex screw in for testing.l as It wouldn't have aligned. 

Will have to do a bit of work to tighten it up, rotating the shaft in the extruder is a challenge. But hopefully this will solve the issue! Will report back.

 

Posted : 15/10/2021 3:20 pm
Ed
 Ed
(@ed-5)
Active Member
Topic starter answered:
solved

So it wasn't just the gear was loose, the grub screw had come out... So after a bit of prodding and poking and partial disassembly I managed to locate it, tighten, reassemble, calibrate (the IR calibration made a hell of a lot more sense... Far less force required!)

I'm now 3 colour changes into my first test print! Fingers crossed.

Thanks for your support. Will watch the video, the lights on the MMU and those buttons still confuse the hell out of me. But super happy to have something working 👍

Posted : 16/10/2021 6:21 am
Rick Houlihan
(@rick-houlihan)
Active Member
RE: solved

 

Posted by: @ed-5

So it wasn't just the gear was loose, the grub screw had come out... So after a bit of prodding and poking and partial disassembly I managed to locate it, tighten, reassemble, calibrate (the IR calibration made a hell of a lot more sense... Far less force required!)

I'm now 3 colour changes into my first test print! Fingers crossed.

Thanks for your support. Will watch the video, the lights on the MMU and those buttons still confuse the hell out of me. But super happy to have something working 👍

Good to hear you got it working, it might hiccup a few times until you figure it all out but at least it's printing. 🙂

Posted : 17/10/2021 2:16 am
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