[3.4.0b7] Issue with Bed PID

Fred-Y

I'm having troubles to properly PID the bed on my Predator, below is the log of the one I just did.

12/24/2021, 2:30:58 PM	Warning: heater behaviour was not consistent during tuning
Auto tuning heater 0 completed after 5 idle and 25 tuning cycles in 2856 seconds. This heater needs the following M307 command:
 M307 H0 R0.292 K0.227:0.000 D1.04 E1.35 S1.00 B0
Send M500 to save this command in config-override.g
12/24/2021, 1:55:28 PM	Auto tune starting phase 3, measuring
12/24/2021, 1:48:39 PM	Auto tune starting phase 2, settling
12/24/2021, 1:43:26 PM	Auto tune starting phase 1, heating up
12/24/2021, 1:43:21 PM	M303 H0 S60
Auto tuning heater 0 using target temperature 60.0°C and PWM 1.00 - do not leave printer unattended

With the suggested values, the firmware triggers an error because it's not getting hot fast enough.

Heater 0 fault: temperature rising too slowly: expected 0.24°C/sec measured 0.12°C/sec

The diameter of the bed is 380cm and it has a magnetic sheet plus a 4mm glass on top of it (I often switch between PEI and glass), also the bottom of the bed is insulated - all of that is likely to create some thermal inertia.

I'm pretty sure I didn't had this issue with 3.3 but I don't remember if it happen with the previous 3.4 beta - I don't mind testing specifics beta version or rolling back to 3.3 if this is useful.

CabalSoul

I’m having the same issue with my predator and a magnetic PEI sheet. Also insulated and with an enclosure.

I’m re tuning my most common Temp ranges 58,70,85,110.

I had some partial success(with completing a tuning process) , if I start my Bed PID tune already warmed up from a previous tuning process.

Exerqtor

Have a look at this.

Fred-Y

@exerqtor Thanks for the tip!

I installed b7+1 and rerun the PID, I had the same warning and similar parameters.

Warning: heater behaviour was not consistent during tuning
Auto tuning heater 0 completed after 6 idle and 25 tuning cycles in 2947 seconds. This heater needs the following M307 command:
 M307 H0 R0.292 K0.273:0.000 D1.04 E1.35 S1.00 B0
Send M500 to save this command in config-override.g

But it seems that now I can heat the bed without any issue, I try in the next few days to heat it from room temperature.

Fred-Y

With the exception of the PID warning "heater behaviour was not consistent during tuning" which might be caused by my tick bed everything appears to know be fine with b7+1, from my perspective I think this issue can be marked as resolved.