Changed extruder - filament get stuck

olemandt

Changed extruder - filament get stuck
November 03, 2014 09:23AM

Registered: 9 years ago
Posts: 5

Hi,

I changed from the stock j-head extruder on my Prusa i3, to a metal j-head version. When I feed the extruder with filament manualy by hand it extrudes a couple of cm of filament, then it suddenly get stuck. When i pull out the filament it looks like shown in the pic.

Does anyone have clue what the problem might be??

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ggherbaz

Re: Changed extruder - filament get stuck
November 03, 2014 10:24AM

Registered: 10 years ago
Posts: 1,401

Several reasons for that, but resumes to 2 main things: a clone j head most likely, and lack of active cooling.
If you used it only for ABS, then you can use it as it is, but for PLA you will have to modify it substantially to prevent jams.
Post a photo of your hot end assembly please.

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Floyd

Re: Changed extruder - filament get stuck
November 03, 2014 11:41AM

Registered: 10 years ago
Posts: 770

I bet you dont have a fan cooling your hot end all the time.

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Srek

Re: Changed extruder - filament get stuck
November 03, 2014 01:44PM

Registered: 12 years ago
Posts: 2,470

Are you trying to use 1.75 mm filament with a 3mm hotend? The diameter of the blob is much to large for other causes imho.

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

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Floyd

Re: Changed extruder - filament get stuck
November 03, 2014 01:52PM

Registered: 10 years ago
Posts: 770

The thought did cross my mind but id hope that no one would try to place 1.75mm filament into a 3mm hot end!

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ggherbaz

Re: Changed extruder - filament get stuck
November 03, 2014 02:59PM

Registered: 10 years ago
Posts: 1,401

I thought the same, but couldn't believe it.

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olemandt

Re: Changed extruder - filament get stuck
November 04, 2014 02:40AM

Registered: 9 years ago
Posts: 5

Hi again.
It should be a 1.75 extruder (at least thats what I ordered - see pic for the extruder) and i'm using 1.75mm PLA. When I come home today I can measure the blob at the end. I dont have fan cooling when this is happening, because it happens right away when i feed the filament in to the extruder before I even starts to print.

Thanks so far for the help

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Srek

Re: Changed extruder - filament get stuck
November 04, 2014 04:39AM

Registered: 12 years ago
Posts: 2,470

The blob is so precisely cylindrical that my guess is that they sent you a 3mm hotend. It is much easier for the filament to flow back upwards inside of the hotend than being pushed through the nozzle. This blob will then cool down and prevent further material from entering the hotend.

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

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rhmorrison

Re: Changed extruder - filament get stuck
November 04, 2014 05:08AM

Registered: 14 years ago
Posts: 3,742

YES, that would be my guess as well based on the picture supplied.

Quote
Srek
The blob is so precisely cylindrical that my guess is that they sent you a 3mm hotend. It is much easier for the filament to flow back upwards inside of the hotend than being pushed through the nozzle. This blob will then cool down and prevent further material from entering the hotend.

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

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tmorris9

Re: Changed extruder - filament get stuck
November 05, 2014 01:51AM

Registered: 11 years ago
Posts: 1,171

I agree, you got a 3mm version.

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olemandt

Re: Changed extruder - filament get stuck
November 05, 2014 02:52AM

Registered: 9 years ago
Posts: 5

Hi guys, I measured the tip (blob) yesterday and like some of you said it was bigger than the 1.75 filament. So the hotend is now sent back to the shop, with a request of a 1.75 version in return .

Thanks for the help, much appreciated thumbs up

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botfeeder

Re: Changed extruder - filament get stuck
November 06, 2014 01:26PM

Registered: 10 years ago
Posts: 59

When you are manually feeding the extruder, make sure the temperature reaches around 180C for PLA.
For quality plastic filament, the only cause for this blob tip is the temperature is not hot enough to melt the plastic completely.

BotFeeder - Professional Manufactured 3D Filament

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