Hot end: Auto tune of heater 1 failed

geekness

Hi, I've just finished my 3d printer build and am trying to complete a successful hot end auto tune, but I keep getting the same error.
Im a bit of a newb at this, so im sure im doing something wrong. Hopefully somebody can help.

Here is my gcode and settings from tonight.

10:02:52 PMWarning: Auto tune of heater 1 failed due to bad curve fit (A=3655.1, C=227.0, D=4.6)
9:59:24 PMAuto tune phase 3, peak temperature was 296.2
9:59:12 PMAuto tune phase 2, heater off
9:58:47 PMAuto tune phase 1, heater on
9:58:41 PMM303 H1 S240
Auto tuning heater 1 using target temperature 240.0°C and PWM 1.00 - do not leave printer unattended
9:42:06 PMWarning: Auto tune of heater 1 failed due to bad curve fit (A=3822.9, C=222.0, D=4.3)
9:38:43 PMAuto tune phase 3, peak temperature was 299.0
9:38:30 PMAuto tune phase 2, heater off
9:38:06 PMAuto tune phase 1, heater on
9:38:00 PMM303 H1 S240
Auto tuning heater 1 using target temperature 240.0°C and PWM 1.00 - do not leave printer unattended
9:35:27 PMG28 X
9:24:46 PMM106 S0.3
9:22:27 PMM120
G91
G1 Z25 F6000
M121
9:22:18 PMM120
G91
G1 Z25 F6000
M121
9:18:01 PMM307 H1
Heater 1 model: gain 340.0, time constant 140.0, dead time 5.5, max PWM 1.00, calibration voltage 0.0, mode PID, inverted no, frequency default
Computed PID parameters for setpoint change: P13.4, I0.482, D51.4
Computed PID parameters for load change: P13.4
9:17:01 PMM303
Heater 1 tuning failed
9:16:20 PMWarning: Auto tune of heater 1 failed due to bad curve fit (A=3411.4, C=198.1, D=4.2)
9:16:01 PMM303
Heater 1 is being tuned, phase 4 of 4
9:14:03 PMM303
Heater 1 is being tuned, phase 4 of 4
9:13:17 PMAuto tune phase 3, peak temperature was 294.9
9:13:05 PMAuto tune phase 2, heater off
9:12:42 PMAuto tune phase 1, heater on
9:12:36 PMM303 H1 S240
Auto tuning heater 1 using target temperature 240.0°C and PWM 1.00 - do not leave printer unattended

Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
Firmware Electronics: Duet WiFi 1.02 or later
Firmware Version: 2.02(RTOS) (2018-12-24b1)
WiFi Server Version: 1.22
Web Interface Version: 1.22.6

Im using 24V, and an E3D PT100 sensor.

DocTrucker

What does your temp plot look like? Sharp spikes can indicate dodgy connection, failed sensor, or electrical noise.

Sharp drops made mine fail.had tp replace a sensor, but it was a standard thermistor.

Phaedrux

Is the heater cartridge and PT100 cartridge firmly secured in the heat block?
Do you have a fan blowing on the heat block?

dc42

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

geekness

The temperature plot looks smooth. The only problem is that it doesn't stop heating until it reaches the maximum temp which is set to 280°

Everything in my hot end feels secure, although come to think of it I haven't tightened it in its heated state.

My cartridge is definitely 24V.

Phaedrux

@geekness said in Hot end: Auto tune of heater 1 failed:

My cartridge is definitely 24V.

Confirmed by measuring resistance?

Assuming it's an E3D: https://wiki.e3d-online.com/E3D-v6_Assembly#Heater_Cartridge

geekness

@phaedrux
Hmm, no-not tested.
I'll test it tonight when I get home. What kind of resistance should I be looking for each voltage cartridge?
What is the resistance value I should be getting for 12V vs 24V?
Im pretty sure its a 40W cartridge either way, but It should be easy enough to figure out

Phaedrux

@geekness From the link:

Heater inserted into block.
If you have one, grab a multimeter and check the resistance of your heater cartridge against the table below. Expect your value to deviate a little from these, a difference of around plus or minus 5W is fine, however if yours is significantly off or you are concerned you have the wrong cartridge please get in touch.

P\V 12v 24v
40w (Red Leads) 3.6Ω 14.4Ω
25w (Blue Leads) 5.76Ω 23.04Ω
30w (Blue Leads) 4.8Ω 19.2Ω

geekness

@phaedrux I came home tonight and checked my heater cartridge, and yes it is a 12V cartridge.
I swapped it out for a 12V cartridge then ran auto tune again, and voila, I now have a functioning hot end. Thanks.

dc42

@geekness, I assume you mean that you swapped it for a 24V cartridge. I'm glad you got it working.

geekness

@dc42 haha, yes woops. Swapped it out for 24V. Thanks again

gruen

I have the same error.

Warning: Auto tune of heater 2 failed due to bad curve fit (A=1665.2, C=423.3, D=5.9)

I use the 65W High Temperature Heater Cartridges from E3D with PT1000.

What can I do?

deckingman

@gruen The A parameter is the gain and I believe that it is also a fair indication of the temperature that the heater could reach if running at full power. Aluminium melts at about 660 Deg C so your heater is dangerously over powered. Is it a 12V one running on 24V?

gruen

I use the 24V from here:
https://e3d-online.com/high-temperature-heater-cartridges
with https://e3d-online.com/v6-plated-copper-heater-block a titan heat break and
https://e3d-online.com/plated-copper-nozzles-v6.

deckingman

@gruen That combination of a copper heat block which is much better at conducting heat than aluminium, plus a high temperature 65 Watt heater probably explains why you could potentially reach around 1,665 deg C and melt mild steel, let alone copper or aluminium. You need about a quarter of that heating power. 20 Watt would probably work but AFAIK the smallest E3D do is 30 watt. Try one of those.

gruen

I need 400°C for print with PEI. I don't think this work with 20 Watt.

dc42

The reason for the error is that the predicted maximum temperature is above 1500C. The solution is to use a less powerful heater, because the one you are using is way too powerful. 40W would be sufficient, probably even 30W.

As a temporary workaround, you could use M143 to set the maximum permitted temperature to 1200C, which will cause the firmware to allow up to 1700C predicted maximum temperature. Then you can use M307 to set those A, C and D values. Then use another M143 command to set a more reasonable temperature limit.

But I repeat, you should use a less powerful cartridge so that in the event of heater control failing, the risk of fire is reduced.

deckingman

@gruen said in Hot end: Auto tune of heater 1 failed:

I need 400°C for print with PEI. I don't think this work with 20 Watt.

65 watts is giving you the potential to reach 1665 deg C. So on that basis and assuming a linear relationship between heater power and hot end temperature, then 20Watts would you the potential to reach (1665/65*20 ) = 512 deg C. But as I said, you'll probably find that a 20 watt cartridge is hard to find so try a 30 Watt which would give you a maximum temperature in the order of 768 deg C using the above assumptions.

gruen

With M143 workaround works the auto tune.

After successfull auto tune does M500 only write:

; config-override.g file generated in response to M500

; Heater model parameters
M307 H0 A C D S V B0
M307 H1 A C D S V B0
M307 H2 A C D S V B0
M307 H3 A C D S V B0
; Workplace coordinates

dc42

M500 doesn't yet work when using Duet 3 with attached RPi. Put the M307 command with the values from tuning directly in config.g instead.