Duet Wifi - Thermistor issues

[Jarery]

Is it possible my Duet wifi is failing and causing my thermistor issues ?

I have a voron 2.4, running on a duet wifi + duex5, with a hartk toolhead board and a revo PZ hotend.
I was printing asa at 260 and HF obsidian nozzle clogged. Put in a new non hf nozzle, and was using sun cleaning filament to make sure it was clean before printing and it clogged.

I think the nozzle is not actually getting to the temp it's stating. So it's clogging because its only at say 210 instead of 260.

I changed the revo 60w heater to my old 40w heater thinking the thermistor was at fault, same thing. Heat to 260, can't get any flow, just a small amount coming out like it's barely hot enough. Now when I heat to 260 I get heater faults. I did rerun pid.

I can't believe I had 2 thermistors fail right after one another with minutes, so suspect it may be the Duet Wifi board. Is that possible ? Would moving the sensor from E0 to E1 help ?

Edit : using an infrared thermometer I measure 76c on the nozzle when I have the hotted set to 160c, so im only getting about half the temp.

Edit 2: moved HE thermistor to E3 on duex board, no change. I read a 75C nozzle when set to 160C. At room temp it reads correctly. The bed temp, he temp and chamber temp thermistors all read the same at room temp. the bed and chamber read correctly at printing temps. It's just the HE only gets to half what I have it set for, even though it shows its at full temp. Im stumped.....

Edit3: measured resistance of the 40w heater/thermistor is 119 K ohms at 21C.

Config :
;; Hotend
;RRF 3.x
M308 S1 P"e0temp" Y"thermistor" T100000 B4725 C7.06e-8 ; sensor 1
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M143 H1 S280 ; set temperature limit for heater 1 to 280C
M307 H1 R3.691 K0.426:0.000 D1.81 E1.35 S1.00 B0 V24.1 ; Revo 40W-

m122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 3.5.3 (2024-09-18 11:25:32) running on Duet WiFi 1.02 or later + DueX5
Board ID: 08DDM-9FAM2-LW4SD-6JTF0-3SJ6J-TLZHY
Used output buffers: 3 of 26 (18 max)
=== RTOS ===
Static ram: 23376
Dynamic ram: 75984 of which 112 recycled
Never used RAM 11080, free system stack 116 words
Tasks: NETWORK(2,nWait 6,13.8%,217) HEAT(3,nWait 5,0.1%,168) Move(4,nWait 5,0.0%,300) DUEX(5,nWait 5,0.0%,23) MAIN(1,running,86.1%,742) IDLE(0,ready,0.1%,29), total 100.0%
Owned mutexes:
=== Platform ===
Last reset 00:21:10 ago, cause: software
Last software reset at 2024-12-15 12:19, reason: User, Gcodes spinning, available RAM 11728, slot 1
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0041f000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
Error status: 0x00
Aux0 errors 0,0,0
MCU temperature: min 25.9, current 33.3, max 34.6
Supply voltage: min 23.9, current 24.2, max 24.5, under voltage events: 0, over voltage events: 0, power good: yes
Heap OK, handles allocated/used 99/25, heap memory allocated/used/recyclable 2048/1120/800, gc cycles 0
Events: 1 queued, 1 completed
Driver 0: standstill, SG min 0
Driver 1: standstill, SG min 0
Driver 2: standstill, SG min n/a
Driver 3: standstill, SG min n/a
Driver 4: standstill, SG min n/a
Driver 5: standstill, SG min 0
Driver 6: standstill, SG min 0
Driver 7: standstill, SG min 0
Driver 8: standstill, SG min 0
Driver 9: standstill, SG min n/a
Driver 10:
Driver 11:
Date/time: 2024-12-15 12:48:02
Cache data hit count 4294967295
Slowest loop: 31.37ms; fastest: 0.18ms
I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0, resets 0
=== Storage ===
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest read time 1.4ms, write time 32.5ms, max retries 0
=== Move ===
DMs created 83, segments created 3, maxWait 533242ms, bed compensation in use: none, height map offset 0.000, max steps late 0, min interval 0, bad calcs 0, ebfmin 0.00, ebfmax 0.00
no step interrupt scheduled
Moves shaped first try 0, on retry 0, too short 0, wrong shape 0, maybepossible 0
=== DDARing 0 ===
Scheduled moves 29, completed 29, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 5], CDDA state -1
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters -1 -1 -1 -1, ordering errs 0
=== GCodes ===
Movement locks held by null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
Daemon is idle in state(s) 0
Autopause is idle in state(s) 0
Q0 segments left 0
Code queue 0 is empty
=== Filament sensors ===
check 0 clear 5118572
Extruder 0 sensor: ok
=== DueX ===
Read count 1, 0.05 reads/min
=== Network ===
Slowest loop: 77.57ms; fastest: 0.00ms
Responder states: HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0)
HTTP sessions: 1 of 8
=== WiFi ===
Interface state: active
Module is connected to access point
Failed messages: pending 0, notrdy 0, noresp 0
Firmware version 2.1.0
MAC address 5c:cf:7f:a4:a1:64
Module reset reason: Turned on by main processor, Vcc 3.41, flash size 4194304, free heap 37948
WiFi IP address 192.168.2.232
Signal strength -54dBm, channel 6, mode 802.11n, reconnections 0
Clock register 00002002
Socket states: 0 0 0 0 0 0 0 0

[dc42]

@Jarery IR thermometers need a large surface area to look at. They are useless for measuring nozzle temperature.

Hot end clogs are usually caused by the cold side getting too hot due to insufficient cooling, not by insufficient heat.

If you suspect that you are getting incorrect temperature readings and changing the thermistor didn't help, check the reading at room temperature, and try a different thermistor input on the Duet.

[oliof]

also try a resistor of appropriate resistance in lieu of a thermistor to check whether the duet reports the right temperature.

[Jarery]

@dc42

In my post I mentioned most of what you suggest.

I have swapped out the thermistor/heater for a backup, no change.

at room temp it matches the temp of the 2 other thermistors in the system, all 3 read 19.2 C.

Yes I agree a handheld laser thermometer is not great, but it happens to read the nozzle temp accurately at room temp, and when I set it to 160 it only reads 75. its such a deviation that I think any inaccuracy is accounted for.

I also already switched thermistor inputs to E3 on the duex board, no change.

I agree that clogs happen by lack of heat, but I added a brand new, unused nozzle, and cannot get hand fed filament to come out. The nozzle is not heating to melt temp even though the UI on both panel due and dwc says its at temp.

It was working, it stopped working, my config didn't change. Asking if the board itself which is now old could possibly be the cause,

[jens55]

@Jarery, I have had a similar situation happen once - it turned out to be a defective extruder. The extruder worked fine with no load but fed intermittently when the filament needed to pass through the nozzle. The root cause was a busted bearing.
While it may not be that, it's worth investigating (it took me a long time to find that issue)

[dc42]

@Jarery said in Duet Wifi - Thermistor issues:

Yes I agree a handheld laser thermometer is not great, but it happens to read the nozzle temp accurately at room temp

That's because everything it can see around the nozzle is at room temperature. I repeat, an IR thermometer is useless for reading nozzle temperature. It's reading the average temperature of an area of which the nozzle is a small part.

An FLIR camera may give you a more accurate reading, but bear in mind that the nozzle won't be quite as hot as the melt zone or the heater core.

[Jarery]

@dc42

I understand about the temp reading, trying to find a solution.

I have nozzle jams on every print, after running fine for years.
I'm asking if it could be the board itself as the cause ?

Revo system for last year, 60W heater, duet3d wifi board, latest rrf.

What ive done :
-dried the filament
-changed thermistor
-changed heater
-changed hotend fan
-changed hotend fan S value to max
-run a hotend PID
-changed extruder pins on the controller
-taken apart extruder and cleaned everything
-reprinted any extruder parts that looked sketchy
-slowed down to 9 mm^3/s max flow

im running out of what I can change, so im asking if it could be the board, somehow. But that's an expensive swap if the board cannot be at fault.

[dc42]

@Jarery see the response earlier from @oliof about how to test the temperature reading accuracy of the Duet.