Broken Hotend Thermistor Wire
I recently attempted a print with Hatchbox PLA filament and about 2 hours in I come back and find the entire nozzle and hotend covered with a massive glob of PLA and my printed parts are all over the place. I stopped the print and pulled off as much gunk as I could and I ended up breaking one of the hotend thermistor wires. Is this something that I could replace without ordering a whole new hotend?
Also can I turn on the heat to clean up the excess gunk still all over the hotend without the thermistor? I'm worried about the hotend overheating since there is no temperature sensor.
Re: Broken Hotend Thermistor Wire
First do not heat the hotend without a thermistor. The heater cartridge is powerful enough to melt the aluminium heater block without temperature control. Instead use a hot air gun to clean the heater block and nozzle until a new thermistor cartridge is obtained.
A new thermistor cartridge can be purchased separately.
From Prusa
Or for faster replacement from the following but you will need to do some soldering to join the thermistor to the existing leads at the end of the high temperature part and will need some heat shrink as well.
E3D Online if you are in Europe
MatterHackers if you are in the US
A Soldered Shrink-wrapped Replacement (Sourced From E3D)
Regards,
Martin
Martin Wolfe
RE: Broken Hotend Thermistor Wire
I just had the exact same experience, also with PLA. Bummer. I had just started a 14 hour run, and I stuck around for the first hour or so to make sure that all of the 20 pieces adhered to the bed properly, which they did. When I came up here this morning, there was NOTHING on the bed - whatever happened, it pulled all the pieces off the bed and kept extruding, then registered a jam. As I pulled the plastic glob off the hotend, the Thermistor pulled out of its housing (the 3mm dia plug), which remained in the Extruder head, but was initially not broken. Then, as I removed the plastic bits, the wire broke (I actually think I broke the wire as I was trying to insert it into its housing, which was still in the Head). There's about 3mm of wire extending from the tip, so I'm going to try to solder it together, and use a heat gun to remove the remaining plastic that is preventing me from getting the 1.5mm allen wrench into the set screw to remove the thermistor body. Initially, I didn't realize the thermistor had pulled out of the head, but noticed the head smoking after I hit preheat - hopefully I didn't do any damage. I have ordered a new thermistor from PrintedSolid.com - we'll see how fast it gets here.
RE: Broken Hotend Thermistor Wire
Hello edwin-b5! So we recently experienced the same exact thing - almost verbatim including the thermistor wire hanging down after removing the PLA gunk. I just ordered a new hotend and reviewed the instructions for replacement. It looks complex - how did you resolve your problem? I'm curious about how long it took and any tips that folks have.
Thanks and I hope you're happily printing again!
RE: Broken Hotend Thermistor Wire
@martin-w15
Have you had any issue with the wire that you soldered on melting? I had the exact same issue and currently I cannot get a replacement. I am able to solder a new length in but I'm worried about the insulation melting and leaving the lead exposed.
RE: Broken Hotend Thermistor Wire
Did anyone come up with a solution for this??? I'm having the same problem, and without being able to heat up the head, I've been using a heatgun, but I may have stripped the screw holding in the hotend. Now I can't unscrew the screw to replace the hotend parts I've got replacements for. Really quite frustrating. Mines a Prusa i3 MKS+, and I've only been using it a month or so. My Prusa mini has been FAR more reliable because of this seemingly "simple" problem.
Log into your Eshop account, navigate to Company, click Contact Us and 24/7 live Chat is one of the options. This is the quickest route to Prusa support.
Cheerio,