PLA jams in the hotend

Hi,

I'm new here, so please excuse if I ask silly questions. I recently bought a 3D printer and assembled it. It works fine without filament. The problems start when I try to actually print something. The filament jams somewhere in the hotend's heat insulation. I tried decreasing the temperature and using the fan but it didn't help. I'm only able to extrude around 3 - 4 cm of PLA. After that it jams. I suspect the problem is within the hotend itself. The heat insulation has threaded end which is much thiner than the rest of the insulation

It gets hot and the PLA stucks inside. The hotter the hotend the higher the filament jams. Is there anything I can change to stop this behavior? Replacing the hotend is also an option.

Cheers,
milosz

Hi Milosz,

maybe it won't get hot enough?

When you start printing, you have a small volume of the filament molten - when pushing new (cold) filament in the hot zone, it will push down the melting zone, so you'll need more heat to melt the new entering filamnet fast enough, so it won't jam ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Is there a teflon tube inside the PEEK?
If NOT, then that is your problem.

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

Viktor,
I tried everything from 140*C to 200*C. The hotter it gets the faster it jams

Bob,
I don't think there is any teflon inside. The inner diameter is just around 3mm and I don't see signs of any other material inside. According to the seller it was meant for 3mm filament. So it looks like new hotend is the only option?

Cheers,
milosz

... i have PLA-beads, normally used for injection moulding, that are rated from 180 degC to 230 degC, so some PLA blends can need or work with higher temps than 200 degC.

Can you measure the temperature of your hotend with a reliable thermometer? - the value shown in the softare can be off ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

i would ask the supplier about it. There is no reason to get a machine and have hot end problems. There are many good designs out there and if the supplier decided to make there own as it looks like they should stand behind it. Do you know if they recomend pla? Abs is more forgiving to poor hot end designs.

If there is no teflon then even if it works once it cools down and then heats up again it will be jammed.
The coeficient of friction is just too high with PEEK.

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

Viktor,
I just checked with DS18B20 (I don't have anything better). The readings are within 3*C for thermistor and Dallas thermometer. I only checked for 100*C as the thermometer has maximum temperature of 125*C. But it looks like temp reading is pretty accurate in this case.

Gulf,
I'd rather go and buy a new hotend than talk to the seller. I already heard a lot from this guy and had enough. The PLA came with the machine so I guess it was recomended.

Cheers,
milosz

rhmorrison Wrote:
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> If there is no teflon then even if it works once
> it cools down and then heats up again it will be
> jammed.
> The coeficient of friction is just too high with
> PEEK.

That is exactly what happens. It jams, I clean it, try again and it jams again

Cheers,
milosz

I changed hotend to J-Head and the problem disappeared. Thank you for your help!

Cheers,
milosz