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Filament stuck in extruder

Posted: Sun Jun 24, 2018 11:19 am
by iguanaman
I started a print job (fairly large) with some white filament from MatterHackers. After about the 10th? z layer I noticed that the extruder wasn't putting down any plastic. I have restarted the print several times with the same result. The gear where the filament is pulled down (gear next to bearing) wears a notch in the filament. Photo attached. Does anyone know what might cause this? I am using PLA with the "Village plastics" setting and high quality. I am using the recommended settings and not custom. Is it a problem with the PLA I am using or something else?

Re: Filament stuck in extruder

Posted: Sun Jun 24, 2018 12:43 pm
by Ehoff
For starters what toolhead are you using when this happens? It looks like heat creep, which PLA is known for. Heat creep is when the heat travels up the heat break from the nozzle and starts to soften the filament at the hobbed bolt, and once it starts to soften there, the hobbed bolt just chews into the softened filament rather than catching on it and pushing it down and out the nozzle.

Generally when using white PLA, try reducing the hotend temperature to 195C and see if that helps any. Also, now that a bite mark has been cut into the filament, make sure to clear the residual filament out of the teeth of the hobbed bolt, otherwise you can see the problem happen sooner, do to the teeth being filled with plastic and not being able to bite down on the filament and feed it into the extruder.

Re: Filament stuck in extruder

Posted: Sun Jun 24, 2018 12:53 pm
by iguanaman
The tool head is the single extruder that ships with the Taz 6. I saw that there was residue on the gear so I've cleaned it out each time that happens. I'll try reducing the temp and seeing that that helps the issue. Thanks!

Re: Filament stuck in extruder

Posted: Sun Jun 24, 2018 1:42 pm
by iguanaman
I tried some different PLA and noticed that the temperature was already set to 195. Should I drop the white to 190 or 185?

Re: Filament stuck in extruder

Posted: Sun Jun 24, 2018 7:53 pm
by iguanaman
I also got the same problem with some translucent green PLA. The model has a lot of support structure (10 diameter moon) on the bottom which covers almost the entire print bed. I haven't run into this issue before so I am wondering if the large amount of retraction might cause the issue along with the heat creep. I am going to test with a much smaller version of the model and see what happens.

Re: Filament stuck in extruder

Posted: Mon Jun 25, 2018 9:18 pm
by PeterT
Couple other things to check:
1. Build plate/tip clearance. If you are consistently failing at the same point in the print, it could be back pressure from the filament being too close to the build plate.

How are your first layers? Clean?

2. Retraction: if your retraction is too long, you could be sucking hot plastic back into the heat break. With direct drive heads, you should rarily need more than 1-1.5mm retraction. Certain plastics, such as PETG may need 2.0.

Re: Filament stuck in extruder

Posted: Tue Jun 26, 2018 9:28 am
by Luis
iguanaman wrote:
Sun Jun 24, 2018 1:42 pm
I tried some different PLA and noticed that the temperature was already set to 195. Should I drop the white to 190 or 185?
You could try 190 i guess

Re: Filament stuck in extruder

Posted: Tue Jun 26, 2018 7:11 pm
by iguanaman
PeterT wrote:
Mon Jun 25, 2018 9:18 pm
Couple other things to check:
1. Build plate/tip clearance. If you are consistently failing at the same point in the print, it could be back pressure from the filament being too close to the build plate.

How are your first layers? Clean?

2. Retraction: if your retraction is too long, you could be sucking hot plastic back into the heat break. With direct drive heads, you should rarily need more than 1-1.5mm retraction. Certain plastics, such as PETG may need 2.0.
It doesn't fail at exactly the same point each time.
First layers are clean but 99.9% support to begin with since the object is a sphere.
Retraction is default at 1.0

Re: Filament stuck in extruder

Posted: Wed Jun 27, 2018 9:44 am
by PeterT
Two things:

1. Looking at the filament image, I suspect you have your idler too tight. Try backing it down. When filament grinds, usually it goes about half way through (or less), your seems awfully deep.

2. Can you post a pick of a failed print? I would like to see the top of the model.

Re: Filament stuck in extruder

Posted: Wed Jun 27, 2018 11:57 am
by iguanaman
Yes it is pretty tight. It is a struggle to get it on. It has been that way since i bought the machine so i thought that was the way it is supposed to be. I will have to get the print set up again and i will post a picture.