bad model parameters

ander

Hi there!
Every time i power on my delta printer puts "bad model parameters" on the screen.
And a warning that says heater 1 predicted maximun temperature at full power is 660C.
This is my output of m115 :
m115
FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi/Ethernet FIRMWARE_VERSION: 3.4.6 ELECTRONICS: Duet WiFi 1.02 or later FIRMWARE_DATE: 2023-07-21 14:08:28
And this is my config.g
config(1).g
Can someone please give me a hand?

droftarts

@ander A 'bad model parameters' is usually related to heater configuration. If I send the two M307 commands from your config.g, I get the following response:

M307 H0 R0.083 K1.473:0.000 D5 E1.35 S1.00 B0
Error: M307: bad model parameters: estimated temperature rise too small
M307 H1 R3.841 K0.319:0.000 D7.07 E1.35 S0.50 B0 V23.9
Warning: M307: Heater 1 predicted maximum temperature at full power is 656°C

I would guess that the H0 parameters have come from having updated the firmware, which has converted older M307 commands (which I can see on the same line as your current setting) to the parameters used by the new version of the command. Sometimes this doesn't seem to work well (I believe this has been fixed in newer firmware), and you seem to have a very low R parameter of R0.083, which is saying it will take 1 second to raise the temperature of the bed 0.083C, or take 12 seconds to heat up 1C, or take roughly 12 minutes to get to 60C. Is your bed that slow?

If I send your old parameters (I'm using RRF 3.5.2) I get:

M307 H0 A215.5 C661.6 D5.8 S1.00 V24.0 B1
Warning: M307: Heater 0 predicted maximum temperature at full power is 240°C
M307 H0
Heater 0: heating rate 0.326, cooling rate 0.151, dead time 5.80, max PWM 1.00, mode bang-bang
Predicted max temperature rise 215°C

So something like M307 H0 R0.326, K0.151:0.000 D5.80 E1.35 S1.00 B0 may be more accurate for your heater.

Probably the easiest thing to do is retune the bed (and probably the hot end too) with M303. See https://docs.duet3d.com/en/How_to_guides/Commissioning#h-7-tune-heaters

The warning message is just that, saying that the hot end heater can potentially get very hot, based on the model parameters. Not an error, but it shouldn't be ignored that you hot end heater is powerful!

Ian

ander

@droftarts
You are rigth, all the problems started when i upgraded the firmware.
It was giving me errors when heating up the bed. i runned m303 several times, try to do some changes and didn´t work and i changed the heating element for a more powerfull 220v silicon one. the bed itself is 460 in diameter, and yes, it takes a while to heat up.
i run m303 back again to show the results, and see if we can get someting out of it.
m303 h1 s220
Auto tuning heater 1 using target temperature 220.0°C and PWM 0.50 - do not leave printer unattended

Auto tuning heater 1 completed after 3 idle and 5 tuning cycles in 386 seconds. This heater needs the following M307 command:
M307 H1 R5.033 K0.424:0.000 D7.16 E1.35 S0.50 B0 V23.8

m303 h0 s90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended

M307 H0 R0.175 K0.111:0.000 D15.43 E1.35 S1.00 B0
Send M500 to save this command in config-override.g

ander

@droftarts
Can anyone help me? it is still giving me the same error.
i run m303 several times, then m500 and still same error when powering on the printer.
Thanks

dc42

@ander I think you still have the old heating parameters in the M307 commands in config.g. Try replacing them with the parameters from the M307 commands in config-override.g.