Changed thermistor - auto tune failing

interwebsdesigner

I just changed out my hot end from one of those chinese hotends to the E3D which has a different thermistor. I tried to auto tune and it is failing, not sure if I have my settings correct.

Failure Message:
Warning: Auto tune of heater 1 failed due to bad curve fit (G=1869.8, tc=199.7, td=4.7)

Config.g

[[language]]
;*** You can use S and B parameters to define the parameters of the thermistors you are using. Standard 100k thermistor from E3d is 4388 or 4725.
M305 P0 T100000 B4388 R4700 H0 L0   		; Put your own H and/or L values here to set the bed thermistor ADC correction
M305 P1 T100000 B4725 R4700 H0 L0   		; Put your own H and/or L values here to set the first nozzle thermistor ADC correction
;M305 P2 T100000 B4388 R4700 H0 L0  		; Put your own H and/or L values here to set the second nozzle thermistor ADC correction

;***Choose if you want to use the M301 or the autotune results and M307 command. Don't use both.
;M301 H1 P10 I0.10 D100 T0.50 S1.0  		    ;PID settings for extruder 0 (no need for M301 if using M307)
;M301 H2 P10 I0.10 D100 T0.50 S1.0   		;PID settings for extruder 1

M570 S120                					;Increase to allow extra heating time if needed

;*** Bed Heating Controls & Max Tem
M143 H0 S140

;***Use for autotune. Comment out M301 if you do.
M307 H0 A142 C293.5 D5.4 B0 				;Autotune result for bed
;M307 H1 A588.5 C242.9 D6.7 B0				;Autotuen result for first nozzle

any help would be appreciated. Thanks!

interwebsdesigner

I added the C param and it still did not function properly. Still failed.

M305 P1 T100000 B4725 C7.06e-8 R4700 H0 L0 ; Put your own H and/or L values here to set the first nozzle thermistor ADC correction

Warning: Auto tune of heater 1 failed due to bad curve fit (G=2056.0, tc=151.2, td=4.4)

dc42

The gain is much too high. Are you using a 12V heater cartridge with a 24V supply?

interwebsdesigner

24V supply yes, not sure about the heater. Unfortunately when I was building my printer I went through a few and honestly didn't look. I have an unopened labled 24v heater here from E3D.

The heater was working before with the old thermistor.

So I used the P0.25 when auto-tuning and it passed but gave me the overheating warning.

First question I have I guess would be should I switch out the heater or is there way to check and see what type of cartridge it is?

Second, is setting the P0.25 param when auto tuning acceptable?

interwebsdesigner

I changed out the heater cartridge for the 24v version. Ran auto tune again with P1 and it worked perfectly. The curve looks nice and the heat is steady while printing.

Sorry for the newbie questions, I am sure this was a beginner mistake… will pay closer attention to these details in the future.

Thanks

dc42

To check the heater cartridge voltage, see step 9 at https://e3d-online.dozuki.com/Guide/V6+Assembly/6?lang=en.