M2's repeatedly stop extrusion mid-print

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mlamparter
Posts: 6
Joined: Wed Aug 28, 2019 2:47 pm

M2's repeatedly stop extrusion mid-print

Post by mlamparter » Thu Apr 21, 2022 7:32 pm

Apologies if this is has been resolved a hundred times over. I did spend a bit of time digging on the forums and found some related posts, but nothing that seemed to directly address my issue. I am curious to get others' feedback and experience. Feel free to redirect me.

I work at a university and have been an M2 champion for almost a decade. Between our makerspaces we have 10 M2's. We performed various upgrades to them over the years and I think we're all running v4 hotends, latest firmware, BuildTak flex plates, LCD's, etc. I still like our M2's better than some of our other, newer printers and find that in general they are more reliable and produce better prints than other printers. So I am a believer. But we have been facing an issue now for several years that is frustrating and I'm at a point where I need to ask the community for help.

Seemingly randomly we have prints that fail due to the printer simply stopping extrusion mid-print. The printer keeps moving, the extruder motor keeps rotating, but filament ceases to extrude. I print only Overture brand PLA (the other makerspace prints mostly ABS, but I am not aware of the brand). I have tried increasing and decreasing tensions after following Jules's helpful guide viewtopic.php?f=3&t=2694. Unfortunately, that did not resolve the issue. I feel confident we have the proper tension dialed in and we can usually print for several weeks without issue. But eventually, prints begin to fail due to mid-print halt of extrusion again. It seems the only consistent thing we have found to correct the issue is to install a fresh filament drive. We typically print our filament drives out of ABS or PETG. Our machine shop has even go so far as to machine little Delrin inserts to place in the top of the filament drive to guide filament and hopefully reduce wear on the filament entry point. But to no avail.

Does anyone else experience what I am dubbing "filament drives wearing out" as often as we are experiencing? Are there other things that I should be checking here? Thanks for your consideration.

These are two other, similar threads I came upon, but I didn't come away with any solutsion from them I hadn't already tried:
viewtopic.php?f=7&t=6466&p=35828&hilit= ... ing#p35828
https://forum.makergear.com/viewtopic.p ... 9338051475

Gwhite
Posts: 342
Joined: Tue Jul 11, 2017 3:38 pm

Re: M2's repeatedly stop extrusion mid-print

Post by Gwhite » Thu Apr 21, 2022 9:00 pm

The problem I've had with filament drive wear is at the bottom, not the top. Here's a thread with some of my adventures:

viewtopic.php?f=7&t=6565&start=10#p36240

airscapes
Posts: 554
Joined: Wed Jan 31, 2018 11:36 pm

Re: M2's repeatedly stop extrusion mid-print

Post by airscapes » Fri Apr 22, 2022 4:23 am

They are made of plastic and they wear out no doubt about it. I got one off of the net some years ago which is better for TPU than the stock model, I have attached it. The other thing that fails is the drive gear on the extruder motor, it slips.. If when you remove the filament from a failed print as you explained and there is no damage from the gear grinding on it, you may have a failed drive gear. If the filament is all chewed up and the replacement of the housing fixes it for an extended time then it is just wear and tare. I like to use ABS from my drive housing, PETG lasts longer but ABS prints cleaner for me. Glad you mentioned this as I am on my last housing I had in stock and should probably print a few more. Things that wear out for me is the exit end above the hot end and the spring end .. Other things that can cause this is an intermittent break in a wiring harness or bad thermistor..

Gwhite
Posts: 342
Joined: Tue Jul 11, 2017 3:38 pm

Re: M2's repeatedly stop extrusion mid-print

Post by Gwhite » Fri Apr 22, 2022 2:26 pm

One thing that I always thought might make them last longer is to install a thin brass tube on the lower end. That would have eliminated the wear that killed mine. The drive has to push the filament into the hot end against a certain amount of resistance. The filament will want to flex to the side in some direction under the force. The bowed filament will wear the inside of the hole wherever that occurs, eventually increasing the amount it can bow. That leads to more wear, and eventually things go wonky.

In my case the drive gear wasn't well position on the shaft when it arrived, and the filament could flex towards the end of the gear. Eventually the housing wore to the point where it started slipping off the end of the gear.

Adding a grooved sleeve to the bearing should also help to keep the filament from wandering. I originally did it to work with TPU (which I've never gotten around to), but it should also provide a little more guidance & support to keep regular filament running straight. Details are in this thread:

viewtopic.php?f=7&t=6724&p=36959&#p36959

mlamparter
Posts: 6
Joined: Wed Aug 28, 2019 2:47 pm

Re: M2's repeatedly stop extrusion mid-print

Post by mlamparter » Fri Apr 22, 2022 3:27 pm

Thanks for everyone's thoughtful and speedy responses. I like the idea of adding a thin brass tube at the bottom. We have tweaked the design of the filament drive a bit which I think has extended the life of drives, but like you mentioned - they're plastic so they will eventually wear out. The filament is always chewed up with a worn groove when extrusion ceases so I think our drive gear is fine. I'm just relieved to hear that this is about par for the course with everyone else.

airscapes
Posts: 554
Joined: Wed Jan 31, 2018 11:36 pm

Re: M2's repeatedly stop extrusion mid-print

Post by airscapes » Fri Apr 22, 2022 4:12 pm

mlamparter wrote:
Fri Apr 22, 2022 3:27 pm
Thanks for everyone's thoughtful and speedy responses. I like the idea of adding a thin brass tube at the bottom. We have tweaked the design of the filament drive a bit which I think has extended the life of drives, but like you mentioned - they're plastic so they will eventually wear out. The filament is always chewed up with a worn groove when extrusion ceases so I think our drive gear is fine. I'm just relieved to hear that this is about par for the course with everyone else.
I am sure you have done this since you seem to have covered your bases, but when the housing is screwed to the extruder, it can rotate with the sloop in the screw holes of the housing. You must make sure the filament enters the center of the hot end to reduce the side pressure in the plastic housing above. If the plastic housing is rotated, the filament hits the side of the hot end as it enters and puts undue pressure on the exit of the the plastic housing and will accelerate your wear.

mlamparter
Posts: 6
Joined: Wed Aug 28, 2019 2:47 pm

Re: M2's repeatedly stop extrusion mid-print

Post by mlamparter » Tue May 03, 2022 1:02 pm

@airscapes - YES! This has irked me for a while. I always have a tough time getting the filament to enter the center of the hotend. I typically grab the filament drive with a pair of vice grips and try to torque it as much as possible to keep it properly aligned with the hotend before securely fastening it in place. But invariably I see it slipping and the filament wanting to travel off-center before it enters the hotend, as evidenced by a little pile of filament shavings on top of the hotend. It just seems like there must be a better design out there.

Gwhite
Posts: 342
Joined: Tue Jul 11, 2017 3:38 pm

Re: M2's repeatedly stop extrusion mid-print

Post by Gwhite » Tue May 03, 2022 3:00 pm

I have to be careful getting it aligned initially, but I've never had a problem with my drive slipping or with filament shaving. You may want to loosen the mount for the hotend, and see if you can scoot it a bit in the right direction.

Phil
Posts: 208
Joined: Mon Sep 19, 2016 7:49 pm

Re: M2's repeatedly stop extrusion mid-print

Post by Phil » Wed May 04, 2022 4:45 pm

There is one more thing you might consider checking; I had this problem.
Even though you see the extruder gear moving, is it possible it sometimes quits? I had a broken connection in the wires leading to one of my extruders, and it would extrude intermittently, leaving voids/gaps in the layers. It is hard to detect until it gets really bad, too, so all the more frustrating.
Anyway, it might be worth checking.

mlamparter
Posts: 6
Joined: Wed Aug 28, 2019 2:47 pm

Re: M2's repeatedly stop extrusion mid-print

Post by mlamparter » Wed May 04, 2022 5:38 pm

Thanks for the suggestion, @Phil! I had not thought of that. I'll go back and do the ol' "wiggle-and-check-continuity" test.

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