[SOLVED] Heated bed PID auto tune failed.

dc42

Your tuning run reported:

G=118.2, tc=794.1, td=-0.6

So the M307 command you need based on these values would be:

M308 H0 A118.2 C794.1 D-0.6

However, the dead time can't be negative. So measure the time it takes from turning the bed heater on to the indicated temperature starting to rise. For example, if it is 4 seconds, use:

M308 H0 A118.2 C794.1 D4.0

I have it on my work list to improve the measurement of dead time during auto tuning.

HTH David

deckingman

@dc42 said in Heated bed PID auto tune failed.:

I have it on my work list to improve the measurement of dead time during auto tuning.

I've always struggled in that respect with my big thick lump of aluminium tooling plate and have to manually change the auto tune value. No big deal as it's not something that needs to be done often, but it would be nice to see that improved if it's possible.

dc42

@deckingman said in Heated bed PID auto tune failed.:

@dc42 said in Heated bed PID auto tune failed.:

I have it on my work list to improve the measurement of dead time during auto tuning.

I've always struggled in that respect with my big thick lump of aluminium tooling plate and have to manually change the auto tune value. No big deal as it's not something that needs to be done often, but it would be nice to see that improved if it's possible.

Can you tell me what value auto tuning reports, what happens if you use that value, and what value you actually use to get good results?

deckingman

@dc42 said in Heated bed PID auto tune failed.:

@deckingman said in Heated bed PID auto tune failed.:

@dc42 said in Heated bed PID auto tune failed.:

I have it on my work list to improve the measurement of dead time during auto tuning.

I've always struggled in that respect with my big thick lump of aluminium tooling plate and have to manually change the auto tune value. No big deal as it's not something that needs to be done often, but it would be nice to see that improved if it's possible.

Can you tell me what value auto tuning reports, what happens if you use that value, and what value you actually use to get good results?

Now you've got me. I made a note in my config of the date I last ran auto tune and it was 17-08-2017, so over a year ago. Thinking about it, (and my memory is a bit hazy) I seem to remember that prior to that time, I really struggled to get a successful tune, but you made some changes which fixed the problem that I had - it was something to do with the check it makes after the heater turns off (can't remember what that check is). So now that I think about, you may have fixed the dead time issue too.

I'll run another auto tune when I get chance - bed is hot at the moment and it'll take about 3 to 4 hrs to get down to ambient. I can say that I'm using D16.4 so that would indicate that it came from auto tune and not a post tune manual entry (I'd have rounded it to a whole second).

vapvap

@dc42
I'm sorry, but I think I'm doing something wrong...

7:43:07 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=133.8, C=839.5, D=-0.5)
7:30:11 PM
Auto tune phase 3, peak temperature was 90.0
7:30:04 PM
Auto tune phase 2, heater off
7:22:08 PM
Auto tune phase 1, heater on
7:22:02 PM
M303 H0 S90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
7:21:45 PM
M307 H0 A83.9 C552.1 D20.0
6:46:16 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=83.9, C=522.1, D=-0.3)
6:38:16 PM
Auto tune phase 3, peak temperature was 90.1
6:38:09 PM
Auto tune phase 2, heater off
6:31:45 PM
Auto tune phase 1, heater on
6:31:39 PM
M303 H0 S90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
6:31:15 PM
M307 H0 A102.6 C642.0 D17.0
6:22:21 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=102.6, C=642.0, D=-0.1)
6:12:29 PM
Auto tune phase 3, peak temperature was 90.2
6:12:22 PM
Auto tune phase 2, heater off
6:05:14 PM
Auto tune phase 1, heater on
6:05:08 PM
M303 H0 S90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
6:04:45 PM
M307 H0 A102.0 C633.4 D15.0
5:48:31 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=102.0, C=633.4, D=-0.9)
5:38:47 PM
Auto tune phase 3, peak temperature was 90.0
5:38:40 PM
Auto tune phase 2, heater off
5:31:40 PM
Auto tune phase 1, heater on
5:31:34 PM
M303 H0 S90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
5:31:22 PM
M307 H0 A163.0 C1031.9 D12.0
5:21:56 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=163.0, C=1031.9, D=-0.3)
5:06:05 PM
Auto tune phase 3, peak temperature was 90.1
5:05:58 PM
Auto tune phase 2, heater off
4:57:09 PM
Auto tune phase 1, heater on
4:57:04 PM
M303 H0 S90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
4:56:48 PM
M307 H0 A78.8 C487.0 D10.0
2:26:11 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=78.8, C=487.0, D=-0.9)
2:18:43 PM
Auto tune phase 3, peak temperature was 90.2
2:18:36 PM
Auto tune phase 2, heater off
2:12:24 PM
Auto tune phase 1, heater on
2:12:19 PM
M303 H0 S90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
2:12:01 PM
M307 H0 A141.7 C892.4 D7.0
2:08:46 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=141.7, C=892.4, D=-0.7)
1:55:02 PM
Auto tune phase 3, peak temperature was 90.0
1:54:55 PM
Auto tune phase 2, heater off
1:46:39 PM
Auto tune phase 1, heater on
1:46:33 PM
M303 H0 S90
Auto tuning heater 0 using target temperature 90.0°C and PWM 1.00 - do not leave printer unattended
1:45:29 PM
Connection established!
1:45:29 PM
Page Load complete!

deckingman

@vapvap It's the negative dead time that's screwing it up but I don't know why you are getting that. Are you starting from a low ambient or are things really hot in your part of the world?

vapvap

@deckingman Normal room temperature (~20C).

dc42

What happens if you use a lower target temperature such as 70C?

The bed needs to be allowed to cool down completely to room temperature between tuning attempts.

vapvap

@dc42
11:20:51 PM
M307 H0 A181.2 C1041.0 D4.0 P0.5
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
11:20:43 PM
M307 H0 A181.2 C1041.0 D4.0 P0.6
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
10:39:52 PM
M307 H0 A181.2 C1041.0 D4.0 P0.7
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
10:39:27 PM
M307 H0 A181.2 C1041.0 D4.0 P0.8
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
10:38:52 PM
M307 H0 A181.2 C1041.0 D4.0
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 206C.
10:21:55 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=181.2, C=1041.0, D=-0.8)
10:05:55 PM
Auto tune phase 3, peak temperature was 70.3
10:05:48 PM
Auto tune phase 2, heater off
10:00:36 PM
Auto tune phase 1, heater on
10:00:30 PM
M303 H0 S70
Auto tuning heater 0 using target temperature 70.0°C and PWM 1.00 - do not leave printer unattended
10:00:00 PM
M307 H0
Heater 0 model: gain 90.0, time constant 700.0, dead time 30.0, max PWM 1.00, calibration voltage 0.0, mode PID, inverted no, frequency default
Computed PID parameters for setpoint change: P46.3, I0.319, D971.8
Computed PID parameters for load change: P46.
9:59:31 PM
Connection established!
9:59:31 PM
Page Load complete!

dc42

Try with those M307 settings. The warning message is usual when using a high-power bed heater.

vapvap

This post is deleted!

Phaedrux

What type of heated bed is it?

vapvap

@phaedrux Aluminum disc 220mm (Delta Printer).

vapvap

@dc42

In the end, I achieved a positive value.
But what to do next?
After all, the "auto tune" still does not work.

7:20:11 PM
Warning: Auto tune of heater 0 failed due to bad curve fit (A=183.8, C=1042.4, D=0.1)
7:04:11 PM
Auto tune phase 3, peak temperature was 70.3
7:04:04 PM
Auto tune phase 2, heater off
6:58:52 PM
Auto tune phase 1, heater on
6:58:46 PM
M303 H0 S70
Auto tuning heater 0 using target temperature 70.0°C and PWM 1.00 - do not leave printer unattended
6:58:30 PM
M307 H0
Heater 0 model: gain 188.4, time constant 1070.6, dead time 5.0, max PWM 1.00, calibration voltage 0.0, mode PID, inverted no, frequency default
Computed PID parameters for setpoint change: P202.9, I2.773, D710.0
Computed PID parameters for load change: P2
6:58:23 PM
M307 H0 A188.4 C1070.6 D5.0
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 213C.

Phaedrux

@vapvap said in Heated bed PID auto tune failed.:

@phaedrux Aluminum disc 220mm (Delta Printer).

And what is the heating element?

vapvap

@phaedrux said in Heated bed PID auto tune failed.:

And what is the heating element?

https://www.amazon.co.uk/anycubic-MK3-Round-Aluminium-Diameter-Printers/dp/B01LZ36INV

Phaedrux

Ok, now is it wired as 12v or 24v? What is your power supply voltage and wattage?

vapvap

@phaedrux 12V, 30A, 360W.
https://www.amazon.co.uk/gp/product/B072J97N8T/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

Phaedrux

@vapvap said in Heated bed PID auto tune failed.:

https://www.amazon.co.uk/anycubic-MK3-Round-Aluminium-Diameter-Printers/dp/B01LZ36INV

Please note: There is no Thermister not installed on the card or including in the list. Please, install the precisely Thermister

The listing says the bed doesn't come with a thermistor. What thermistor are you using and do you have the right configuration values for it?

vapvap

@phaedrux 100K Wired NTC Thermistor 3950
https://www.ebay.co.uk/itm/100K-Wired-NTC-Thermistor-for-3D-Printers-3950-RepRap-Marlin-EPCOS-Flux-Workshop-/113189674857?hash=item1a5aa15f69