Filament jammed in J-Head

Hello,

during printing this evening, at some point the PLA filemant on the printed object startet to be interrupted (picture bottom.jpg) and I observed that the filament was not entering the entruder, altough the gear was moving.

I tried to reverse the extruding but even while pulling the filament by hand, it came out only a short distance. After opening the extruder, I saw, that the filament is jammed at the top end of the J-Head.

Tomorrow I will try to put the J-Head into a bench, heat it up under Melzi control and additionally heat-up the top end with a hot air blower (which I still have to buy...). Hopefully I can then remove the filament by pulling it with a pair of pliers ...

Any hint for an alternative way to remove the filament?

On the occasions that I have had a jam I found the best way to remove the filament is to snip it at the top of the hotend then heat up an alan key and melt it into the filament and unscrew the set screw. Once the set screw is out you can pull the filament and ptfe liner straight out.

I'm not sure if you know (I didnt at first) but at the very top of the hotend is a hollow set screw which the filament passes through, this holds the ptfe liner in place.

I have removed pla a bunch of times by just using a hot gun and then pulling out the filament with plyers it works the easiest, you don't need to heat up the hotend through the printer that way.

Good luck.

The method to remove the filament with an hot air blower worked fine. But it takes a while to heat-up the top end of the J-Head.

When assembling the extruder again, I discovered some cracks in the idler block, near to the bearings. After assembling the extruder works as before and I hope the cracks will not become bigger.

When I calibrated the extruder, I saw some smoke coming out of the extruder. I assume, that the temperature of 220 °C which I used for the faberdashy PLA, is to high for the new PLA filament I'm using now. I reduced the temperature to 200°C and a test piece was printed better as before.