Thermal runaway when trying to remove nozzle
 
Notifications
Clear all

Thermal runaway when trying to remove nozzle  

  RSS
matthew.s14
(@matthew-s14)
New Member
Thermal runaway when trying to remove nozzle

Hey all, I am trying to remove the nozzle from the stock hot end but when I heat it to abs temperature (255 degrees) and attach my crescent wrenches to the heater block and nozzle the temperature plummets immediately by about 30 degrees and the nozzle won't budge when reasonable force is applied. Within about 8 seconds the temperature drops far enough to trigger a thermal runaway and the heater shuts off. I know that you have to bring it to temperature to remove the nozzle so I am wondering if this sharp temperature drop is actually a problem in this case or if it is just a quirk of the positioning of the Thermistor and its ok to try and crank the nozzle off while the temperature reading is plummeting.

thanks in advance,
Matt

Posted : 08/08/2017 9:41 pm
PJR
 PJR
(@pjr)
Antient Member Moderator
Re: Thermal runaway when trying to remove nozzle

Yeah, the temp will drop rapidly; try to use an adjustable wrench and a piece of fire blanket (or woven glass fibre) in the jaws and push the temp to 275.

It will still drop, but maybe not as fast...

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…

Posted : 08/08/2017 10:36 pm
Neal
 Neal
(@neal)
Reputable Member
Re: Thermal runaway when trying to remove nozzle

If I understand correctly in this case the wrench became a heat sink when it touched the nozzle?

Neal

Posted : 08/08/2017 10:41 pm
matthew.s14
(@matthew-s14)
New Member
Topic starter answered:
Re: Thermal runaway when trying to remove nozzle

Awesome! thank you so much for the rapid response! ill look around for a suitable insulator, I don't think I have anything on hand but it should be easy to acquire it

Posted : 09/08/2017 1:06 am
AJS
 AJS
(@ajs)
Noble Member
Re: Thermal runaway when trying to remove nozzle

Are you sure you are not crimping the thermistor wires and getting a bad connection? That will also cause a sudden drop in temperature (reading).

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 or loss. If you solve your problem, please post the solution…

Posted : 09/08/2017 4:02 am
Share: