PETG extrusion - stalled motor

Yep got the email, thanks for your reply.

The question you had brought up about how my initial purge went, well it's been a long time since I have done the initial purge. But I do remember it being very hit or miss. The extruder would sometimes stall/the extrusion speed would be really low and motor torque low as well (0.5-0.7a.) The stall protection board was set correctly to start restricting the torque when the motor drew around 1.6-1.7 amps but depending on the moment etc the motor would stall or under extrude. I believe that there's something wrong with the way I shred my failed filament spools. In that, I don't know if it's the grease in the paper shredder (I tried to reduce the amount) or just the remelting cycles breaking down the plastics. But whenever I try to extrude virgin pellets my extruder stalls, and whenever I extrude recycled pellets my extruder under extrudes with low load.

The hopper design I made is supposed to expose as much of the cut out section as possible to hopefully use the auger a little to help agitate the pellets. So far I have never had any kind of poor pellet feed.: https://drive.google.com/file/d/1izYrZV … sp=sharing

This is my full setup, it is very temporary and I really need to move it to a better vented area. I have not been so good to my health with this one: https://drive.google.com/file/d/1PLtdYv … sp=sharing

The barrel doesn't seem to be warped in any way and the auger doesn't make any weird grinding sounds while empty, other than the very occasional squeak.
https://drive.google.com/file/d/1iERWAL … sp=sharing
https://drive.google.com/file/d/1cWRCXl … sp=sharing

I would definitely appreciate sending some more ABS my way to help maybe clean it out more, idk. The end goal is to be able to use PETG of course just because I like its lack of noxious fumes and good layer adhesion. I also ordered a new nozzle as I had drilled mine to 2mm but I don't think I was having overpressure problems. Mostly just barrel wall either friction too high or too low.

I am aware that the auger is from just a normal drill bit, but would you think that replacing it with a proper plastic auger with the tapering feature would yield me better results when it comes to extruding recycled filament? With the potential grease and all anyway, as it forces pellets to be smushed against the barrel more and more as it continues its journey. I believe it was documented already how the filastruder has vastly lower operating pressures than an industrial version. The only difference I see is the auger design.

Also the barrel in the images is not insulated, this is because I sort of ruined my insulation after removing and reapplying it so many times. It just doesn't really hold on very well anymore, maybe you could send some additional insulation as well although I am sure I can find something else at the hardware store. Maybe something I could take on and off a bit easier without damaging it.

Update: Thanks Elmoret for the ABS, the extrusion has gone very well. With expected amperage draws sustaining after an overnight run, and my spooler was able to capture it!

https://drive.google.com/file/d/1_08Miz … sp=sharing
https://drive.google.com/file/d/1BBzu5R … sp=sharing

The goal for the dummy winder was just to save on space. I will have to re-spool each completed wind in order for it to be tangle-free. I will probably do this by hand.

The MG94 extruded I believe slower than what I have been hearing and slower than I once extruded the PETG before stalling. It was however consistent and I had no stalls as far as I know, I have been extruding for almost 24 hours and plan to hit that mark tonight. A full 1kg spool will be filled in this amount of time as well. I would like to know if my rates are correct. In the beginning, the pellets circulated around in the barrel until the heat crept up further (probably because some PETG was stuck to the inner core of the auger.) After the constant rotating around in the barrel stopped I started to see filament come through, and the pellets in the hopper were circulating as well. I noticed that they started to turn black, the barrel was very dirty.

Pellets in the hopper: https://drive.google.com/file/d/1DHNrAj … sp=sharing

Video of extrusion rate: https://drive.google.com/file/d/1RxYhtp … sp=sharing

The extrusion rate was conducted with temperatures set to 170C with a motor current of 1.65 - 1.8 Amps, set the motor voltage to 11v I believe to eliminate the subtle noise change when the heater kicks on.

Tomorrow I will attempt PETG again or perhaps continue extruding ABS, overall I am very pleased to know that my extruder does work, however, I am not sure how well it is currently working. I would be curious what kinds of speeds others are able to achieve these days and what might be slowing mine down if it is being slow. Now that I have this additional ABS I can rework my hopper design, I was thinking it might need some more verticality to increase the pressure at the inlet. It also needs more ABS touching the pipe as the blue hopper is made of PLA and is directly touching the pipe, making the connection weak as the PLA gets soft.

Update: The combination of running slower and cutting the insulation back did not solve my problem, as of right now. The Temperature of the nozzle decreased by quite a bit during this run (190c). This may have lead to the stall, the only reason I don't believe it is nozzle pressure-related is that the stalls are immediate and not gradual. I believe stalling occurs during pellet shear which is why I initially believed heating the area would make the pellets softer for shearing, and now I don't know what the problem is since the problem seems to happen after a period of time extruding. So it must be about the amount of material in the barrel, but it doesn't make sense to me because by the time material is showing out the nozzle the entire barrel should be filled? And with a fan directed onto the uninsulated part of the barrel heat creep shouldn't be happening. So I don't know what is "building up" to eventually cause a stall unless it's some anomaly like 2 pellets being sheared at once instead of 1. What I am going to try next is raising the voltage supplied to the heater, I have acquired a few boost converters for another project I have yet to dive into and if I can increase the voltage to perhaps 15-18v I can boost the power of the heater to combat my temperature drop.

I think the damaged bearing is likely the source of most of your headaches, fingers cross that things are solved with the replacement.

Update: After replacing my thrust bearings and overvolting my heater, the stall problem still persists!
So the problem is completely based on shearing pellets as they enter from the hopper, a group of pellets will eventually amass at the inlet and bind up the auger. Unlike ABS, the PETG pellets are extremely durable therefore I have thought of only two ways in which this problem can be solved.

1: The pellets need some kind of inlet that reduces or eliminates the shearing effect, maybe some kind of tapered plastic inlet that will allow them to be rolled up at the side rather than pinched so that they eventually seat into each cavity.

2: The pellets need to be processed more than they already are (the pellets are too big for the extruder) if they can be blended, perhaps made into a powder they will never have to be sheared at the inlet. I don't know if maybe this can be accomplished just by halving their size or if they need to really be powdered. I don't really know how I would go about doing this.

Other than those two, I have not had success with my stock filastruder. Despite cranking the amps up to 3A the shear strength of the PETG is far too strong for the motor to overcome comfortably, and I advise against buying it even though it may sound like the ultimate material. TLDR, it is not a dream in the land of extrusion, and you would be better off perhaps trying to conquer PLA if the durability aspects of PETG are not something you require. Unfortunately for me it is a must! So I need to come up with some way I can get my machine to work with this stuff, and I would really rather not process the PETG pellets as there are so many. I will try to create some sort of inlet design to reduce shearing, but I really cant think of any shape or slope that would handle the forces or not just bind up eventually. It seems like a lost cause in that regard but I thought once I saw someone make one.

Update: You cannot blend PETG pellets, they are too strong. I am now out of ideas.