E0 Temp readings are high

[jdefant]

I recently installed a Titan Aero extruder on my FT-5. I have been having some difficulty with the filament extruding properly so I tested the temperature of the hot end with a calibrated thermistor connected to a Fluke DVM. Things looked pretty good at room temp but then got out of wack pretty quickly as the temperature went up:

Does anyone know how I would go about calibrating the Duet WiFi so that I get accurate temp readings?

Thanks

[jdefant]

Well I answered my own question but I thought I would post for other newbies like myself.

While I was not able to find a data sheet for this particular thermistor (E3D Thermistor Cartridge) I was able to find the correct setting on the RepRapFirmware Configuration site.

In the Config.g file...

; Heaters
M305 P0 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 0
M143 H0 S120 ; Set temperature limit for heater 0 to 120C
;M305 P1 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 1 ;Original
M305 P1 T100000 B4725 C7.06e-8 R4700 ; Set thermistor + ADC parameters for heater 1 ; modified JCD
M143 H1 S280 ; Set temperature limit for heater 1 to 280C

I made these changes and now the hot end temperatures measure within a few degrees of the calibrated Thermistor.

Hope this helps the next guy!

[Phaedrux]

Good work. Have you also run a PID tuning cycle on your hotend?

[T3P3Tony]

@jdefant Glad you worked it out.

It is on the e3d documentation but possibly not quick to find:

https://e3d-online.dozuki.com/Guide/V6+RepRap+Firmware+Configuration/26?lang=en

Interestingly e3d suggest different settings to the B4138 C0 (either B4388 C0 or B4725 C7.060000e-8) potentially try the second one to see if it is even more accurate over your desired temperature range.

Leaving this here in case e3d change the thermistor cartridge in the future.