thermistor wire snapped of i3mk2 hotend
Has anybody had to deal with this and know a fix? Looks like it has snapped through wire fatigue or snagging on a printed part.
Replace the thermistor?
Solder a new wire onto the existing one (looks small)?
Disassemble the hot end somehow?
Get a new hotend?
Little bit stuck here how to go ahead.
Re: thermistor wire snapped of i3mk2 hotend
Depends on where the wire is broken. If it's close to the heater block, solder won't work, so you need to replace: http://e3d-online.com/Electrical/Components/Thermistor-Cartridge
If it's further away from the heat, then it can be resoldered, but keep as much of the glass fibre insulation as possible.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: thermistor wire snapped of i3mk2 hotend
The wires are broken right as they enter the hotend. Still, £4.50 isn't too bad - was worried this could be expensive to fix.
How do I get the old one out to replace it? The thermistor doesn't seem to be held in by any kind of screw. It doesn't help that my hot end is covered in stuck-on black filament!
Re: thermistor wire snapped of i3mk2 hotend
Hi Jim,
there is a tiny grub screw holding the cartridge in place.
may I suggest getting two thermistors. so you have spare for the future!
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: thermistor wire snapped of i3mk2 hotend
Thanks for the info Joan - I'll look for the grub screw when I'm back home.
And good idea on getting two - will do no harm to have a spare.
Re: thermistor wire snapped of i3mk2 hotend
I've found the grubscrew but it wouldn't turn with even quite a lot of force. Eventually the hex head gave in and the key turned without moving the screw.
Is this normal? It seems to have been provided from Prusa tightened much tighter than such a tiny head should sensibly be tightened down.
Any ideas how to remove this now?
Re: thermistor wire snapped of i3mk2 hotend
Heat it to about 200°C and try again. But be careful it will be hot! 
Re: thermistor wire snapped of i3mk2 hotend
Possibly glued in place by pla...
Hence the heat suggestion.
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: thermistor wire snapped of i3mk2 hotend
That was correct! I heated it with a hot air gun and the grubscrew came out with hardly any force at all!
Now does the thermistor just push out from the non-wire side? I tried but with quite a lot of force it isn't moving.
Re: thermistor wire snapped of i3mk2 hotend
Pla glue again?
Heat it up and push the cartridge out
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: thermistor wire snapped of i3mk2 hotend
I actually just had the same thing happen to me.
Since the thermistor was dead I couldn't heat the hot end that way.
I had to use a torch to carefully heat it up then the screw loosened.
Then to get it out I had to heat it a bit more and use an allen wrench on the wire entry side to push it out.
After it was out I could see a crushed area from the screw that made it difficult to take out.
So when you get the new one installed make sure to not tighten it up too much.
Re: thermistor wire snapped of i3mk2 hotend
I also am replacing my thermistor. I purchased a replacement and it came with couplers that will allow an easier replacement in the future. Can any one explain how to open the Rambo Case so that I can connect the new wire with the fast connector already added?
Re: thermistor wire snapped of i3mk2 hotend
Never mind. Finally saw the screw on the side staring at me. 😳
Re: thermistor wire snapped of i3mk2 hotend
Just on a sidenote: this coupler sometimes doesn't couple as well as desired, if you run into odd issues with sensor readings dropping out (Pronterface / OctoPrint) or odd printer Errors, consider soldering or crimping these wires together getting rid of the coupler..
Re: thermistor wire snapped of i3mk2 hotend
I am having the same problem, I don't see a grub screw in mine?!
Re: thermistor wire snapped of i3mk2 hotend
Ollie
Grub screw is underneath next to the nozzle.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: thermistor wire snapped of i3mk2 hotend
I've got a brand new i3MK2, 2/17 build.
So my thermistor wiring broke off - during a run a bunch of PLA piled up around the hot end and somehow this wire was broken off.
Do I need a whole new hot end? Or just a thermistor? I can't sort out what I'm looking at, and everything is coated with PLA.
For example, the grub screw (or hex or torx - hard to tell what it is) is immobile since I can't even get a tool to seat in it. What size of which fixture is it? Can I unscrew the nozzle to look at the assembly? I can't tell what else is holding it in place...
Re: thermistor wire snapped of i3mk2 hotend
Usefull thread! I have a slightly different problem... My thermistor is the old modular one with the connector. One of the two wires came loose from the connector. I cant get it back inside of the connector. Any sugestions?
Re: thermistor wire snapped of i3mk2 hotend
I had a bad print cover the thermistor wires in pla and I accidentally snapped off the wires trying to clean the hot end. You can just replace the thermistor without buying an entire assembly. The issue is that the grub screw seems to consistently tightened a bit too much and it strips when you try to remove it.
For those that used heat to get it out, since it won't turn on without the thermistor, did you remove the heater block from the abs parts to avoid melting them with a torch or heat gun?
I believe the heat advice I'm just not sure how to go about it. Any advice?
Re: thermistor wire snapped of i3mk2 hotend
Does this make a silicon jacket a good idea, if only to keep things clean?