Tuning a hugely overpowered heater

droftarts

@tryptamine I've tried your M307 command on my Duet 3 Mini 5+ on RRF 3.4.2rc1, and PWM responds correctly. You can, of course, send the command directly to set M307.

M307 H1 R10.976 K0.652:0.000 D2.65 E1.35 S0.10 B0 V24.0
M307 H1
Heater 1: heating rate 10.976, cooling rate 0.652, dead time 2.65, max PWM 0.10, mode PID, calibrated at 24.0V
Predicted max temperature rise 809°C
PID parameters: heating P6.1 I0.289 D11.4, steady P6.1 I0.718 D11.4

Also, the command in your config.g M307 H1 R10.976 K0.652:0.000 D2.65 E1.35 S0.10 B0 V24.0 doesn't match the output from M307 H1:

Heater 1: heating rate 2.430, cooling rate 0.560, dead time 5.50, max PWM 1.00, mode PID, calibrated at 0.0V

R=heating rate, K= cooling rate, D=deadtime, S= max PWM. The numbers set by M307 don't match the numbers reported by M307 H1. I think this is happening because of the order of the Gcode commands that define the nozzle heater. The M307 H1 command is after you have set up the bed heater, but before you create the nozzle heater. The order should be M308 (define temperature sensor), M950 (define heater output), then M307 (or M301) to set the heater parameters. So change the order of your heater section to:

; Heaters
M308 S0 P"e1temp" Y"thermistor" T105526 B4138      ; configure sensor 0 as thermistor on pin e1temp (bedtemp BROKEN)
M950 H0 C"bedheat" T0                              ; create bed heater output on bedheat and map it to sensor 0
M140 H0                                            ; map heated bed to heater 0
M143 H0 S120                                       ; set temperature limit for heater 0 to 120C

M308 S1 P"e0temp" Y"thermistor" T103901 B4138      ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1                               ; create nozzle heater output on e0heat and map it to sensor 1
M143 H1 S280                                       ; set temperature limit for heater 1 to 280C
M307 H1 R10.976 K0.652:0.000 D2.65 E1.35 S0.10 B0 V24.0

It also looks like you haven't tuned your bed.

Once again, I urge you to replace the 12V heater cartridge as soon as possible; you are relying on the firmware to protect against thermal runaway, and the 12V heater cartridge has the capacity to do some very serious damage!

Ian

jens55

I am puzzled as to what wiring has to do with all of this. You have an end device that is wrong - replace the damn end device!
As was pointed out, the heater will draw more current than the Duet can supply. In addition, it would be interesting to find out what gauge of wire was used because it likely is insufficient for the current draw. It is also nicely insulated to retain the heat in a fat cable bundle!
Not only is your Duet going to die from drawing too much current, not only are you going to burn down your house with the heater cartridge, you will also burn down your house because of melting wires.
I can't believe that this whole idea is still being talked about .....

Tryptamine

@jens55 That is why I want to limit PWM.
If I send a PWM of 0.25, neither the board nor the wires will be overpowered.

Stop trying to explain electronics to me, I did not ask for it.

Tryptamine

@droftarts Thank you so much for this qualified answer.
You were the only person here really helping me out.

I tried to fix a GCode issue and not to get moral advice from everyone.
And I find it condescending from all the others to put themselves in a position where they feel like they have the right to judge about me and give me commands i just have to follow.

We are all on eye level here. If you want to recommend something, do it like droftarts.
Give your recommendations, but do not impose them, and do not treat me as I am an idiot.

A smoker asks you for a lighter.
You can give a lighter or not.
You can give the lighter and tell them smoking is bad for them (which they probably know already)

But nobody in his right mind would not give a lighter and instead call them an idiot for smoking and start an argument about how stupid his decisions are.
"Oh you TRY to quit? Fucking quit now already! It is dangerous! You are stupid!"

You do the exact same thing only in another domain, and feel totally fine with it. Why so?

deckingman

@tryptamine said in Tuning a hugely overpowered heater:

@jens55 That is why I want to limit PWM.
If I send a PWM of 0.25, neither the board nor the wires will be overpowered.

Stop trying to explain electronics to me, I did not ask for it.

At the risk of encountering your wrath, we do need to explain PWM to you because I can assure you that the board and and wires will be overpowered regardless of what PWM value you use. PWM does not limit the current, it only varies the amount of time that current flows. i.e. the width of the pulse (which is the "P" in "PWM"). But it does not limit the amplitude of the pulse so you'll still be drawing nearly 7 Amps from a board that is only deigned to take 6 Amps.

dc42

@tryptamine also please bear in mind that a 12V heater run from 24V is running at four times (not twice) its intended power. So if it gets stuck on at full power, it will almost certainly melt the heater block. Then it will be free tom the hot end and may contact wiring, plastic or other flammable materials.

I can't see any reason why the S parameter in your M307 command would not be honoured. Please run M307 H1 from the console and check whether it reports the correct PWM limit.

PS - I just tried sending M308 H1 S0.1 and then heating the hot end on one of my printers. As expected, it heated slowly and could no longer reach the required temperature. So the M308 S parameter works for me.

jens55

@tryptamine said in Tuning a hugely overpowered heater:

do not treat me as I am an idiot.

Calling it as I see it .....

I am done with this subject.

droftarts

@tryptamine Has re-ordering the config.g, by putting the M307 H1 ... after the M950 H1 ... , fixed the PWM issue?

Ian

rexx

@droftarts could you explain why the M950 before the M307 changes and what it does or is not just the ordering and would this apply to a chamber>

droftarts

@rexx all heaters need a temperature sensor, so M308 is defined first. The M950 effectively defines the heater, and relates it to the temperature sensor that allows control of it. Before M950, the heater doesn’t exist, so an M307 earlier than M950 that references the same heater applies settings to a non-existent heater. I believe when heaters are defined without M307, they are configured with the defaults for a hot end heater. If you then define the heater as a bed with M140 or chamber M141, these should come next, and I think alter the heater settings to defaults for each. Then set temperature limits with M143. Lastly, set the actual heater parameters you want with M307. This is the order the configuration tool sets, too.

Ian

rexx

@droftarts thank you kindly

Cheers

zapta

@tryptamine said in Tuning a hugely overpowered heater:

I am trying to get to work a 12V heating cartridge on a 24V system.

With 24V do get x4 the power so may need some creating solution. Since splicing the wires for a 24V heater or having a small 12VDC power supply are out of question, have you considered using water cooling to take away x3 of the power?