Hot end: Auto tune of heater 1 failed

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.

gruen

I use the workaround and set with M143 the maximum permitted temperature to 1200°C. After another M143 H2 400 stays the Temperature Chart at 1200°C.
Can I reset the upper limit?

dc42

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

I use the workaround and set with M143 the maximum permitted temperature to 1200°C. After another M143 H2 400 stays the Temperature Chart at 1200°C.
Can I reset the upper limit?

If you refresh DWC, does the upper limit do back down? I have a feeling that DWC rescales its temperature chart when the limit increases, but not when it decreases.

gruen

Oh, my error. M143 H2 S400 works. Thanks.