UM2 Nozzle heater defectiv?

[Robertoho 0]

My son and me, we have an Ultimaker 2 running for several years. We printed a lot and had smaller problems to solve - so we have a little experience, but we're not experts. Just for fun and hobby.

In the last weeks I printed several parts in ABS which worked fine when following some rules against warpage.

Yesterday I tried to print another part and had a new problem: filament extrusion just stopped completly after an hour - in the middle of this object. Extrusion head moved "idle" in the air.

Assuming a stucked nozzle I used the "atomic method" (?) to clean the nozzle. That worked and I restarted the object. This time it print for about 30 minutes, then stopped but continued printing/extruding filament after a while, producing a mess. I aborted again (when I discovered that), this time let the printer completly cool down.

After 2 hours I contiued with doing another cleaning "atomic method" and restartet again the same object. It printed for about 3 hours this time, producing only one little failure in the print when filment was absend for just a second. Then again - stopped extruding filament completly.

This morning I tried another "atomic method" clean. But this time nozzle seems not to melt the ABS filament although saying it has 260 degrees. It's hot, but not hot enough, ABS will only get soft and I can press only  a little thourgh the nozzle (the filament "thread" has normal diameter but wrinkles) with much to much effort (completly different than the other times I did the "atomic method"). When cooling down to 110 degrees (following the display) I cannot remove filament from the head since it's hard already.

So my impression is that the nozzle is much cooler than the display says and while printing, filament stopped coming out of it because of that. And this is for sure a new problem - as I said it worked for years until yesterday.

What to do???

(Damn, I really would NEED this one part for another project...)

P.S. I think I should add that while doing an "atomic method" cleaning when retracting the filament wire with "cool" nozzle, I maybe pulled a bit hard and maybe I moved the nozzle-holder a little. I had to readjust the build table - before I did this last print I mentioned.

Edited November 15, 2017 by Guest

[Robertoho 0]

After some more investigation it seems to me that the heater can hardly be defective when the temperature sensor says, it is 260 degrees hot?

So I have a problem with the temperature sensor?

[tinkergnome 927]

P.S. I think I should add that while doing an "atomic method" cleaning when retracting the filament wire with "cool" nozzle, I maybe pulled a bit hard and maybe I moved the nozzle-holder a little. I had to readjust the build table - before I did this last print I mentioned.

Is it possible that not all parts are back in the right place now? Does the nozzle or the heater block touches the fan shroud somewhere? If in doubt: pictures of the printhead would be helpful (from the front and the back).

Have you measured the real temperature for comparison or is it just a "feeling"?

Is this the "old" UM2 with the spring above the PTFE coupler? Another possible cause is that the PTFE coupler is worn out. It's a consumable part and does not last very long at this high temperatures.

[Robertoho 0]

Thanks.

Yes I checkted all the parts to be in the right place - I took them apart and reassembled for testing.

No, I didn't measure the real temperature. Although I'm quite sure since when displaying 150° the material keeps hard and solid inside the nozzle, when displaying 260° it behaves like 150°: Some can be pressed through the nozzle with much effort, but makes not a propre "thread".

In the meantime I bought a "hot end bundle" and had some more unhappy experiences, but I'm gona open a new thread here....