Heatbed heating to slow

peterartechno

Hello,

I have a huge aluminum plate as a print bed (around 60-70kg of solid). I have two big heating elements strapped to it, with a thermistor in between. The Duet software is telling me that the heating bed is heating slower than the 1.8C/s.

A way to solve this was by using "M303 H0 S60" to manually tune it. This works for one minute but then I get the error "Auto tune cancelled because temperature is not increasing". This is partly true, since the heating elements take some time to heat up 70kg of aluminum.

Is there a way to bypass this feature and let the heater stay on for like 20 minutes?

Kind regards

Veti

you might have to try it manually and set a very large D value

https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control#Section_Setting_the_model_parameters_manually

peterartechno

@Veti Where do I put that, in the config.g file?
instead of this?
M307 H0 B0 S1.00 ; enable bang-bang mode for the bed heater and set PWM limit

I accidentally put it in bang-bang mode, but B0 disabled it I think

Veti

@peterartechno

try something like

M307 H0 A199.0 C962.6 D60 B0

Phaedrux

@Veti said in Heatbed heating to slow:

try something like
M307 H0 A199.0 C962.6 D60 B0

I don't think you even have to specify the A and C values, just specify a large D value.

M307 H0 D300 B0

D is the deadtime between sending a heating command and getting a temperature increase. Based on what you know of the heater setup, how long do you think it should take to increase temp by 1.8c?

And then try to auto tune it with M303 H0 S60

If that still isn't enough, increase the D value more.