Tips for autotuning a very large heated chamber?

droftarts

@p8blr How long does the tuning wait before giving the error? Is the temperature still increasing? Is the chamber able to reach 250C?

I think because you have commented out the existing M307 commands for the two heaters, it is now using the default values. If you send M307 H0 it will report the values being used. I think you will need to increase the D parameter (dead time) to a much longer period. The M307 settings for bed and chamber used before had D182.23 and D43.89 respectively, so perhaps D200.

I can see the point of tuning the bed and chamber together as one heater, as you are mostly likely going to turn them both on at the same time, but then won't it require a macro to separate them into two heaters again, once the chamber is to temperature and before printing starts?

Ian

droftarts

@p8blr After speaking to @dc42, there is a time limit in the auto-tuning for a heater to get up to temperature of 30 minutes for bed/chamber heaters, and 7 minutes for hot end heaters, after which tuning will cancel; I assume you are hitting this time limit. This can only be changed by modifying the firmware.

There are a number of workarounds:

Set a lower target temperature, that can be achieved within 30 minutes. This should still be enough to characterise the heater.
Start auto-tuning at a higher temperature, such that the target temperature can be reached within 30 minutes, and use M303 with an A parameter.
~~Currently, the time limit is only applied to heaters being tuned on the mainboard.~~ Incorrect, the timer is implemented on expansion boards.
How long do you need for the heater to get to temperature? Would 45 minutes be long enough? @dc42 has suggested he can increase the timeout for the next release.

Ian

p8blr

@droftarts Looking at the console, it takes exactly 30 minutes before giving this error. At that point the temperature has risen to 121C. The temperature is still increasing, just not fast enough for the firmware.

I can try starting with the PID values from the chamber alone, increase the dead time, and try PID tuning again.

Yes I think if this process works, I'll have to make a macro or something that will heat the chamber and then separate the bed so it's temp can drop to the chamber temp.

p8blr

@droftarts the 30 minute time limit makes sense, I expect I will need a lot longer than that just due to the amount of air, and thermal mass of the bed + the inner walls of the chamber.

I'll give your suggestions a shot and post an update. It's tough to say how long I'll need, I'm trying to do the calculations to find the heat capacity of the entire system and my heat losses. Perhaps the time to heat limit could be a user parameter? We've actually been trying to compile the firmware ourselves, but we're not very familiar with compiling for arm32 and it's been a challenge to get it to compile without errors.

droftarts

@p8blr I've raised a feature request to add a parameter to override the default timeout: https://github.com/Duet3D/RepRapFirmware/issues/948
That doesn't help you immediately, though!

We've actually been trying to compile the firmware ourselves, but we're not very familiar with compiling for arm32 and it's been a challenge to get it to compile without errors.

I've asked @dc42 for information on what needs changing in the firmware to change the timeout. If you are having trouble compiling, post a new thread with the errors you are getting. I assume you have seen this page? https://github.com/Duet3D/RepRapFirmware/wiki/Building-RepRapFirmware

Ian

droftarts created this issue in Duet3D/RepRapFirmware

open [FeatureRequest]: Configurable timeout for M303 tuning #948

p8blr

@droftarts I'll have to get back to you on the compiling errors, but yes we're using that page as a guide.

On a different note, I attempted to autotune to 60C today, it hit that temperature very quickly, but got stuck in phase 3 and DWC stopped working. Refreshing the page gets to the "connecting" page but that's it. I've tried different phones/PCs but all get stuck at connecting. This has happened a lot before, but I figured it was a normal bug, but now I've noticed that it's correlating with me combining the heaters. It messes it up to the point that when I reboot the printer, that it won't connect again until I pull out the sd card, modify config.g and then start it up again.

Both versions of my config.g are over 2000 characters so I'm just attaching them
workingconfig.g
brokenconfig.g
DriveSetup.g
startup.g
daemon.g

I should also note that I'm running a raspberry pi 4 in sbc mode with a fast 32gb samsung evo card, and I'm on release candidate 2 (same issue with 1)

chrishamm

@p8blr Can you press F12 or open the dev tools in your browser session and check for potential errors in the console? If nothing shows up there, can you please check the duetcontrolserver log? See the section about journalctl in https://github.com/Duet3D/DuetSoftwareFramework/wiki/SBC-Setup-Guide#increasing-log-level.

It doesn't look like DSF loses connection to the Duet so I suspect something else is going on.

p8blr

@chrishamm I'll have to put that code back and run a PID autotune again, I'll get back to you with an update.

p8blr

@chrishamm I changed the settings and restarted and got the error, I didn't even have to autotune.

journalctl -u duetcontrolserver -f

Also I should mention that putty freezes up very frequently when this error happens.

chrishamm

@p8blr If PuTTY freezes as well that probably means the Pi stops working at some point. In that case I'd rather check the electronics again. Are you operating the Pi from the Duet's 5V rail? If yes, consider removing the 5V -> SBC jumper and hook up the Pi to an external 5V PSU.

p8blr

@chrishamm I'm powering the pi via a usb C supply. My suspicion is that because the freezing happens at a regular pace, perhaps it has to do with the daemon.g. Is that possible?

chrishamm

@p8blr I need the full DuetControlServer log to answer that. Your excerpt didn't show anything significant.

p8blr

@chrishamm How do I generate that?

chrishamm

@p8blr journalctl -u duetcontrolserver --no-pager -b

chrishamm

@p8blr I believe this is a duplicate of this report. Can you try out one of those DWC builds and check if it is fixed then? See here.

p8blr

@chrishamm
report.txt

p8blr

@chrishamm I can, I'll get back to you on it...

p8blr

@chrishamm So far I'm not getting any more issues connecting to the web interface with the heaters combined now, just errors that the DWC versions don't match.

T3P3Tony

@p8blr have you refreshed page? this bites me on occasion on upgrades!

p8blr

@T3P3Tony refreshing the page seems to work fine. I know what you mean though, sometimes before when I refreshed the page it wouldn't reconnect.