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Printhead filled with ABS

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Hello everyone,

First post, first big problem.

I had an over night print of >12 hours. When I left the printer (Ultimaker 2) in my office it seems to be working fine. Moment at arrival the next morning I found a big pile of spaghetti (figuratively ofc) on the print bed. In the middle of the spaghetti I found this lava stream looking thing you can see in the first photo.

I cleaned everything up and started printing again. After a few days my printer was acting weird. The lines were to thin with dots in it. When I started doing the usual maintenance I found out that my print head was filled with ABS material still left from my failed >12 hours print. You can see in the photo's that even the sheet metal is slightly bend.

I started heating up the nozzle without the case on it and the ABS came off easily. After I reassembled the print head, the problem of the small dotty lines still exist. I have to tune almost every variable for an barely acceptable (PLA) print. Before the accident the printed printed perfect on the standard settings.

Feel free to respond, all tips are welcome!






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You are surely aware that the teflon coupler in the hot end needs to be replaced every 300-400 hours or so. Printing ABS further reduces his life. You could very well be in a situation in which the coupler is deformed so that you can still print ABS at high temperature, but PLA will fail.

Disassemble the hot end, take the teflon coupler out and have a good look at it. Also see if a filament freely slides in it, or if there is friction. Replacing it could solve your underextrusion problems.

Also, when going from ABS to PLA there is the risk that you carry along tiny bits of ABS that will clog the nozzle at the PLA temperature. So another thing to look at is that everything is entirely clean, the feeder, the tube, the hot end. Some recommend, when changing from ABS to PLA, to make a "dummy" 1 hour print in PLA at the ABS temperature, to make sure every possible debris of ABS is entirely cleaned out. Then you go back to the PLA temperature and print your real thing.


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Since you had the accident with ABS, I would disassemble the print head once more and soak all metal parts in Aceton for a while to remove last remains of the spill. If you have a brass brush for a Dremel, you could also use this to clean the outside of the nozzle from remains if the Aceton does not take care of it.


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Good advices!

Smart to clean it all out first, like reibuehl says.

I would test the teflon coupler WHILE it is in the HOT end.

Remove the bowden tube,

Choose maintenance advanced, heat up nozzle to 220.

Wait 10 minutes (things cannot become worse for you now)..

Insert straight filament from the top, PLA, ie perform the "Atomic Method".

See if it really slides down through the white coupler...


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Thank you for responding.

I think I will try the aceton bath for cleaning up the metal parts. Maybe that there's is burned up material still on the temperature sensor that causes this weird behavior.

Last night I printed PLA with !!!245C!!!, 0% fanspeed on fast speed settings with later on tuned speed reduction of 85%. But still the lines were to thin and barley attaching each other. The print was very flexible, light on weight and pervious sunlight.

I will keep updating


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After reading Swordriff his link about the maintenance guide and how to disassembly the nozzle I saw the note about the warranty issue's from the dealer. I decided to get in contact with my dealer first. She told me that there is no warranty on wear and tear parts. So if I disassembly the print head carefully it wont be a problem from the warranty if suddenly the headed bed will fail.

I followed this guide for removing the nozzle, thank you swordriff:


When I disassembled the print head, I found the nozzle and it looked like it survived the apocalypse. In the red circle is I most likely my problem. I disassembled to nozzle with care and no outraged force was used


I didn't feel cleaning up this mess, so maybe a new nozzle was more likely. But I changed my mind when I saw the price of a new nozzle. I found a ultrasonic cleaner in the office so I tried to clean up the metal parts in this machine. They are still bathing now.


The thermocouple still needs to be replaced. I contacted my dealer with my new issue and they send me a new thermocouple for free, thank you makerpoint.nl for this good service. I hope that I will receive my new sensor soon!

I'll keep you up to date!


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Monday I received my new sensor. The metal parts where bathing the whole weekend and came out really clean. I installed the new sensor and the first prints were perfect, like they used to be.

Thank you makerpoint.nl for quick service and free sensor. And the rest of you for responding!


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