Hotend 'Auto tune of heater 1 failed due to bad curve fit'

[Surgikill]

Hi all,

Trying to tune my hotend on my new machine. It's an e3d supervolcano with a cpap part cooling fan. Running M303 T0 S250 F0.5 and I'm getting

Warning: Auto tune of heater 1 failed due to bad curve fit (R=1.920 K=0.148:0.216 D=8.54)

Here's a graph of the hotend temperature throughout tuning

Here's a screenshot of the command I sent and the console.

It's clearly blowing cold air on the hotend, according to the graph. I'm not even running the cpap blower at full speed. Any ideas?

[Phaedrux]

Have you tried tuning it as a heater instead of tool?

Firmware version?

[dc42]

@Surgikill which firmware version? If I enter m307 h1 r1.893 k0.231:0.454 d8.84 then it is accepted.

[Surgikill]

@Phaedrux I have not tried tuning it as a heater, only as a tool

@dc42 It is:

Board: Duet 3 MB6HC (MB6HC)
Firmware: RepRapFirmware for Duet 3 MB6HC 3.4.4+1 (2022-11-15)

[Surgikill]

@Phaedrux I tuned it as a heater and it seemed to work correctly, so I guess maybe it's just an issue with trying to tune it like a tool?

[Phaedrux]

Super volcano is pretty hefty and well insulated so it doesn't behave as the model expects during the cooling phases with the fan. Tuning as a heater should work fine in this case since you don't have the temp drop issues that tuning as a tool+fan is meant to mitigate.