Help: I messed up nozzle change
I'm so embarrassed but I forgot to remove the PETG filament before I removed the nozzle for a nozzle change. I unloaded the filament immediately when I realized my mistake. However, I can now screw in the new nozzle only very little before it does not go further. I suspect that PETG is now stuck in the thread of the nozzle. Does anyone have any ideas? Do I need to replace parts ? Which ones? How?
RE: Help: I messed up nozzle change
Is the hot end hot when you try to screw the nozzle in?
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Help: I messed up nozzle change
Is the hot end hot when you try to screw the nozzle in?
Yes I heated the nozzle to 285°C. I already ordered a new heatblock an a 6mm tap. If i'm not able to fix the threads, then I will replace the heatblock.
RE: Help: I messed up nozzle change
a tap is a good idea,
I use Coppa Slip, high temperature paste on my heatblock/heatbreak, nozzle 6mm threads to reduce future sticking.
BUT I always catch the first extrusion in tissue paper, after using coppaslip, so that I don't get grease on the build plate.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Help: I messed up nozzle change
Thanks! I'll give that a try, too.
What do you think should I remove the heatblock from the heatbreaker before trying to clean the threads with the tap? Or could it work without disassembling the hotend?
RE: Help: I messed up nozzle change
i would break the hot end down into components, then the tap can clear internal threads and a wire brush can clear external threads, do you have a spare heater and thermistor? you might need them...
please be aware that shorting the thermistor wires, to the heater wires when power is on, is likely to result in a failed controller.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Help: I messed up nozzle change
I am aware of the fragility of the thermistor cables. However I wasn't aware that shortening these cables might lead to the destruction of the controller. A friend also recommended to replace the ptfe liner, but I suppose he didn't quite understand my problem I don't have a problem with clogging of the nozzle.
RE: Help: I messed up nozzle change
Having spares is like insurance, if you have spares available, you don't seen to need them, where as if you don't have spares, you are almost guaranteed to break something! Lol...
the heater wires are at 24 volts when switched on and not printing, when maintaining temperature one leg is switched low, to heat the heater.
the thermistor is ground referenced, if you short 24 volts to the thermistor circuit, the microcontroller will get a bit upset... to say the least!
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Help: I messed up nozzle change
The last time I had the hotend disassembled, I did not use a tap, but an old nozzle to 'chase out' the threads on the heat block to be sure they were free of crud. I used a pliers to hold the heat block and a socket on a 1/4" breaker bar to work the old nozzle in and out, both sides, until the threading was smooth.
Now, I have not done this with the Prusa, but with my other printer I've heated the print heads up to working temperature by using a bench supply.
If you have access to a bench supply, you could heat the block up to operating temperature to soften any impacted filament residue and then chase out the threads with a tap or old nozzle.
RE: Help: I messed up nozzle change
Thanks for that idea! I have a hot gun. Might work as well?
RE: Help: I messed up nozzle change
If all else fails lay the heater block on the ring of an domestic electric cooker (while herself isn't looking).
RE: Help: I messed up nozzle change
I got mine sorted with solvent. Depending on what you've been printing with either acetone or ethyl acetate (see your other thread).
Soak the block and then clean the thread with an appropriate screw or old nozzle.
And when you reassemble the hotend, do youself a favour and ignore the convoluted assembly instructions by Prusa.
First insert the nozzle into the block. Leave the recommended gap with a bit of generosity (thickness of a thumbnail and a wee bit more, sorry didn't measure).
Then insert the heatbreak from the other side until it makes good contact with the nozzle and hand tighten cold. This will make sure that the hot tightening will not move the nozzle inwards enough to make contact with the block
Now do the rest and proceed to install in back into the printer.
When you now do the hot tightening there will definitely be enough of a gap between the nozzle and the block.
Do not forget to redo all you z-calibrations. Really, I mean it! If you forget you might end up in the situation where you'd wished you'd ordered new built plates with you extruder spares 😉
Good luck!
RE:
Thanks for the advices. After removing the heatbreaker i was able to clean the heatblock threads with a 6x1 tap (see image). Afterwards I could reassamble the hotend and the first layer calibration worked 🙂
I'm so happy. I will do more calibration now