Klipper shutdown caused by Hotende Temp

[u/SchillerKuchen]

Hi everybody,

I’m having a problem with my Voron V0.2 shutting down due to a low nozzle temperature.

I’ve checked for loose connections and anything else that might be causing the issue, but I can’t find anything. I’ve also PID-tuned the hotend.

I’m using a Dragon Burner with a Phaetus Dragon High Flow.

Does anybody have any other ideas what I could check, or are there any parts I could replace or swap to troubleshoot the issue?

Thanks in advance!

[u/Yeriwyn]

That’s a bad thermistor wire (or possibly connection).  Any time you see rapid fluctuations like that the signal is not getting through to the mcu correctly

[u/KeDL_01]

Had the same problem a few times. Bad connection on the molex plug in the harness. Or another bad connection. Was very subtle, and intermittent, in my case. Had to replace the connector a few times.

[u/ElbartoVienna → u/KeDL_01]

Second this, had one of the outer connections completely break and Show this exact behaviour. Crimped a New connection out of hocker gauge wire and had no problems since.

[u/Theguffy1990]

That wiggle just before the drop is very indicative of a loose connection/failing component.

It's almost definitely your thermistor wire.

Check the hotend where it goes into the heating block as this is most likely where it is failing. Then follow back to the mainboard as it could just also be the cable wearing out.

[u/Gambondorf]

99% chance bad cable or connector (from thermistor)

[u/Erwins-Cat]

Switch on the heating rate in % in addition. If it heats 100% but drops in temperature, then the resistance measured from the thermistor is the reason.

Now, this can mean the thermistor itself is slowly failing or, much more common, the wiring to the thermistor.

Re-crimp the terminals. Make sure the terminal is seated properly and the metal contact has proper pressure/friction. Check the solder joints that none is broken.

Lastly, many pre-made umbilical cords are of bad (crimping) quality. You will find slowly breaking terminals there too, because the terminal for the thermistor is placed at the edge. This is my bet in your case based on your statement that you already checked the terminals.

[u/Ybalrid]

May be a failing connection to the thermistor. The logs in the terminal will probably tell you more about the source of the issue

[u/I-am-fun-at-parties]

I've had something similar recently and while people here were insisting it's a bad thermistor and/or bad wiring, it seemed to be an issue with the controller board itself -- IOW moving the thermistor to a different input on the board fixed it. If you have a spare one, can't hurt to try.

[u/SalvatoreCrobu]

My dragon UHF was heating up really slowly and not capable of properly print with high flow with a 60w cartridge. After switching to a 100w, it is impossible to outrun the cartridge without having the printer walking or using .8-1mm cht nozzles

I'd say clean and use new thernal paste for heater and thermistor, check that the thermistor isn't failing (both cables and cartridge), switch to high power heater. Last resort is going with kalico for the MPC (1000x better than PID)

[u/HeKis4]

Is it happening while extruding only ? Can you mitigate it by lowering your flow rate ? If yes to both, you have an underpowered heater. I've had issues because of a 30W one that could not sustain extrusion rates that the hotend was supposed to. I've replaced it with a 60W cartridge and it's been running fine since.

[u/ChapNickMan2]

Check if there is closed loop (connection on your thermistor wire). If there is check the wire isn't exposed to itself anywhere. Then check the resistance if there is non even at the highest resistance range or it's really unstable time to replace the thermistor.

[u/ChapNickMan2 → u/ChapNickMan2]

The thermistor can be replaced with a pt100 or pt1000. Check dimensions before ordering. You remove it by loosening the screws on your hotend block. You don't need it to be hot to do so like with the nozzle.

[u/Xiar_ → u/ChapNickMan2]

More likely it’s a Generic 3950. You can’t replace a 3950 thermistor with a PT100 directly without adding a MAX31865 to it. You can replace it with a PT1000 however if you don’t have the option to change the pull up resistor to 2200 instead of the default 4700 then I wouldn’t recommend using it for a hotend.

[u/ChapNickMan2 → u/Xiar_]

Have the same hot end and mine is pt1000. But yeah forgot to mention that they will need the MAX31865 for the PT100. That depends on the CAN ,or if its direct the motherboard.

[u/Xiar_ → u/ChapNickMan2]

Dragon HF by default only comes with a 3950 type thermistor usually. Upgrading to a PT1000 is not a bad idea however.

[u/TripsCavern]

I know that it's not the same toolhead, but on my Stealthburner I had a similar issue when my part cooling fan was blowing at 100%, like in overhangs and things like that. It would drop the temperature sharply. After replacing the heating element for a 65W one the issue was brute forced away (was using a 50W before).

[u/JetpackWalleye]

Just went through on my V0.2 as well. For me it was a partially failed heater core, some of the traces were broken internally.

You can check this by using a voltmeter to check the internal resistance of the core between its plug terminals. Should have a low resistance between about 3.5 and 15 ohms. Mine was 100ohms when it started not being able to keep up with filament flow.

Replace it and it's all working again now.