Hotend jamming kapton transparent

Hi,

I.m having constant jams with my hotend and really need some advice how to solve this issue.

The hotend jams as early as 15-20min during the print. I can still continue if I push the filament with my hand but later on it jams completely.
I have cleaned the heatbarrier and nozzle numerous times and the last time I could get ca 8 hours of printing out of it alltough not without problems.

A strange thing I have noticed is that the kapton tape has become completely transparent after a few hours of printing. If I want to remove the tape from the alu heaterblock I have to scrape it all off. Anyone an idea why this is happening? Is this because of aluminium?
With my brazz heater block I have never seen.this happening.

I'm ready to put in a new thermistor and heater cartridge alltough there are no signs they should be replaced but I see no other solution.

I have added a picture of the filament and how it looks like after a jam accured.
Isn'it strange that the bottom is thicker or is this because the filament has more space in the nozzle?

Hi,
You didn't say what was your hotend exactly.

Do you have any cooling on the cold-end? jamming can generaly be avoided if proper cooling is made to this portion. It avoids the filament to melt in the upper part of the chamber, and stick everywhere making it impossible to push through.

And the shape of the filament in your picture in simply due to the fact that you pulled your filament out of your hotend while it was hot so it stretched. To get a propper removal, it I let it cool down to 60°C, then I can remove all of it in one go, just need to pull a bit harder.

Sorry, I forgot to mention I'm using E3D metal hotend with cooling.

I always let the fan cool the heatsink when I switch off the hotend to prevent jamming in the heatsink(been there)

The jam is in the nozzle during printing. I can't even push the filament trough with 230C.

I have now installed a new thermistor and heater cartridge and will try this tomorrow.

Usually when I pull out the filament it has a long thin end to it from melting and stretching.
The round shape at the bottom in the picture I usually do not have.

Thnx for the advice in removing the filament!

You can just drill through the bore of the nozzle which is what I done with my Prusa Nozzle

Hi,

After I replaced everything my printer jammed again after roughly 20 min.
I noticed the fan on the heatsink wasn't spinning when it happened.

I know the fan always stops spinning when the hotend heats. Is this normal or should always be spinning.

I have the fan connected to 1 wire of the heater and the other on the thermistor.
Should I make a bridge somewhere so the current isn't interrupted?

WHAT?!
Your fan should be wired directly to the PSU 12v and gnd!
Your thermistor should ONLY be brought back to the RAMPS board.

Change this ASAP and hope you didnt kill the thermistor.

I got the same problem, alway jam after 5-10 minutes running. And after full day check, I done.
It jam because the filament too hot in the tube (above the heater), and made the filament melting, become bigger.
I bought a new cooling fan. 12V, 0.12A, same with the original fan, but I saw it faster, stronger.
After that, my printer work ok

Thnx for your reply.

I connected the fan following this image attached wich is in Nophead's manual...

Hi Ngocquynh85,

Good that you found the solution.
It indeed looks like whe are having the same problem.

Can you tell me if your fan stops spinning when the hotend is heating?
And do you have the fan blowing onto the heatsink or are you pulling air away from the heatsink. I have mine pulling air away at the moment.

What electronics do you have? Thats not the RAMPS board im used to.