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Material & Print Head Jammed and melting/burning

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We have had the ultimaker2 working for a week and now have come across a serious problem. (temps = 210 degrees)

Now the material doesn't come out of the print head and infact the print head is now jammed full of material. The Bottom layer of the print head blocks has been melted on 1 of the screw corners and also the wiring to the print head has burned.

Surely this shouldn't happen! The below images show the problem.





So far I've removed the material from the pipe and isolator but I cannot dislodge all the material in the print head even making a hole using a needle when heated to 210+.

What is the fix to this and how can I prevent this from ever happening again?



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how can I prevent this from ever happening again?


Usually this happens when a part gets loose on the print bed and is dragged around and filament just squirts out everywhere including gradually up into the print head.

I'm not sure what you mean by wires are burnt. The Heater cable going into the nozzle has a black area but I think that is burnt PLA and it should be fine.

I'm not sure where there is any plastic left. You didn't show any photos of PLA where it shouldn't be as far as I can tell.

Do you know if the nozzle is clogged at this point? You might want to use the atomic method to clean out the end of the nozzle:


Or you can continue dissassembly (remove the long skinny screw before removing the heater and temp sensor cables as that holds them in) and burn the rest out over a gas flame but don't heat it so much that you melt the metal used for the head (bronze?).


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I'm in the same spot as s.partridge was.


First: illuminarti and gr5 thanks for the huge amount of time you spend helping people. Ultimaker's support has been non-existent.

Anyway I want to take the nozzle off the printer. I've already unscrewed the long allen screw and pulled out the heating cartridge or the sensor (can't tell which is which). From what you said gr5 I assume I just have to pull a little harder on the unit still in the nozzle ? It seems my relatively gentle pulling already pushed insulation back. Not sure I want to rip that thing off !

When I'll put things back together should I - or can I - put some high temp grease on the sensor and heating element ? I have some copper grease (specs say up to 1200°C). Or should parts be assembled "dry" ?

I'm also surprised (well disappointed) that the sensor and heating element come with long cables and hence cannot easily be disconnected near the print head. If I were to damage either cable I assume I'd have to take whole cable out of the back of the printer ...

Maybe, just maybe support will answer my ticket and tell me how to get a replacement nozzle and other spare parts (with all the clogging lately, my bowden tube has some not-so-nice scratches). Or maybe not.

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The heater is the bigger one, so you've removed that. Leaving you with the temp sensor stuck in there. It can be hard to remove. You might try re-inserting the heater, and set the head to heat up to 100º or so - monitoring progress carefully in case the temp sensor is damaged already - and then turn off the power, and see if the temp sensor is now any easier to remove when the block is hot. If not, try hotter still. Be careful of course, as it will be, well, hot. :-)


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Well ... I put the heater back in, heated things up to 100°. Turned the power off and then tried to wiggle the sensor out.

And ... now my sensor is stuck in the nozzle and wires just broke off. Didn't take too much pull.


Hooray !

I just added that little new development to the support ticket I opened a week ago (I wanted a spare nozzle, looks like it's now more of a replacement nozzle !).

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This sucks. The worst thing about it is it may take a while to get a replacement - if it was me I would PM sander and send him to this thread and give him your ticket number - this is urgent because your printer is useless until you get a new nozzle - the sensor you might be able to order or build but the nozzle is cusom.



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Hi guys,

This is the problem I ran into every 3-4 days of printing now. It started with once every 2 weeks then it clogs more often from time to time. My printer (UM2) is at about 1500-1700 hours right now and I understand that any great machine would eventually need to replace parts due to heavy wear. So my question is why didn't the UM team chose to built the nozzle and heatblock as 1 piece? Why don't they build the machine so that the nozzle could just crew off like other cheaper machines? What is the age of a UM2 when users should start thinking about buying replaement parts? Where is the "nozzle/heatblock" combo on UM website so I can order it? I've been thinking just gonna go ahead to buy a heatblock and removable nozzles (for a different machine) off of ebay and try to fit it in my UM2. Due to the intensity of deadlines I have, I cant afford to reprint, wake up at 4 AM to check, realized it clogs, take it apart, clean it, run it again and hope it still work in the morning when I wake up. Thank you....


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