PID tuning failing for larger bed?

I'm working on a printer that previously had a 290x290x3mm Aluminum/PCB heatbed running at 24v. I've swapped out the bed for that's 290x305x6.35mm cast tooling plate with a 350w silicone heater attached. The printer is running Marlin 2.1.1. Not using Bang Bang, MAX_BED_POWER is 127 (half power). I'm trying to PID tune it and it reaches temperature fairly quick, seems to turn the heater off and is waiting for it to settle, but the temperature continues to slowly rise until eventually I get a timeout or temp too high message. Using the stock PID settings in configuration.h Was wondering if anyone had any ideas or maybe some more reasonable PID settings to start off with for this kind of bed.

Below are the ones from configuration.h

#define DEFAULT_bedKp 327.11
#define DEFAULT_bedKi 19.20
#define DEFAULT_bedKd 1393.45

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Fixed, upgraded to 2.1.2.1-bugfix
Now PID acts like I expect.

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Well, can't say this is completely fixed.

I get stutters while around corners printing from SD card on this machine.
Same SD card I and gcode that I used before

All I've done is swapped out the bed, updated the PID values and added a BL Touch.

It only probes 9 points and does a bilinear bed leveling
I know it's not that the board is underpowered, the official Creality firmware is able to do this


I found this happens with the 2.1.2.1-bugfix
I went and transplanted the PID values I got when I ran bed PID tune with bugfix into the 2.1.1.1 release
The bed acts as it should in that version now

But the stuttering, I need some help on.

Machine Details:
Creality Enter 6
Creality 4.3.1 board
Marlin 2.1.1.1

Anyone have any ideas? I'm attaching my configuration.h and configuration_adv.h

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Doh, turns out the SD card was bad.
Using another one and no stutter.

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Dangit, nm, it wasn't the SD card. Anyone have any ideas?

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Where did the PID coefficients come from? They look a bit...odd, shall we say. And why are you limiting the bed power to 50%?
My last thought is that a bad thermal sensor, or a thermal sensor with very poor thermal coupling to the bed, or a thermal sensor
with flaky or intermittent wiring could easily display those symptoms.

The PID settings in the configuration.h are the defaults, I was pretty sure they weren't sane for my setup and was trying to do a PID tune to get proper values.
I originally limited the power to 50% because I would try to have it tune at 60c. It would reach the setpoint and way overshoot. It actually kept going until it tripped the thermal fuse @ 125c

I originally thought it was just the thermal mass of the bed, but when the fuse tripped the temperature response was immediate, as in the temperature dropped quite quickly.
It led me to believe that it was actually still heating after it hit the setpoint.

Updating to bugfix marlin and setting bed power back to full power resolved that, and i was able to pid tune and now the bed heating acts as it should.
I've since taken the new pid values back to the non bugfix version and set bed back to full power and now it works as it should.

The only problem I'm having now is that the print stutters around corners when printing from SD card
I'm not sure why, the only thing really different is that I installed a BLTouch and am using Bilinear bed leveling
It's only 9 points, far less than the stock Creality version of Marlin uses, i know the board is capable to handle the processing

I'm attaching an updated configuration.h and configuration_adv.h

Also, this is using the same gcode I've printed over a hundred times. The only thing I did was add G29 after the G28 in the start gcode

M201 X5000 Y5000 Z100 E8000 ; sets maximum accelerations, mm/sec^2
M203 X500 Y500 Z10 E100 ; sets maximum feedrates, mm / sec
M204 P2000 R3000 T500 ; sets acceleration (P, T) and retract acceleration (R), mm/sec^2
M205 X10.00 Y10.00 Z0.40 E5.00 ; sets the jerk limits, mm/sec
M205 S0 T0 ; sets the minimum extruding and travel feed rate, mm/sec
;TYPE:Custom
G90 ; use absolute coordinates
G28 ; home all axis
G29 ; run bilinear bed leveling
G1 Z20 F240 ; move nozzle to Z20
G1 X189 Y0 F3000 ; move nozzle to X189 Y0
M190 S85 ; wait for bed temp to stabilize
M109 S235 ; wait for nozzle temp to stabilize
G92 E0 ; zero the extruder
G1 E20 F300 ; purge 20mm through nozzle
G92 E0 ; zero the extruder
G1 Z0.48 F240 ; go to first layer height
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0

Edited 1 time(s). Last edit at 02/16/2024 02:17PM by blt3dp.

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Actually think I figured this out. Seems like the Z Jerk was too low for it to be able to move the axis fast enough when bed leveling is active. Seems bumping it up a little worked.

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