First time autotuning… Questions

deckingman

Make sure that your config.g file has this line:

M501                				; Run config-override.g
```(it shluld be near the end of the config.g file)

and yes, you run M303 and after it finishes with the auto-tune you run M500 to store those values.
You can check if they are stored by opening the config-override.g file.

You can also enter the values straight into config.g and not use the config-overide file, in which case you don't need the M501 command.

deckingman

@vbtalent:

OK cool thanks…

[c]M501[/c] ;sets up the writing to the config-override.g

[c]M303 H0 S285[/c] ;I have an E3D hot end, so I assume you would use the max temp?

Then when auto tuning the hotbed simply a change to the max temp something like..
[c]M303 H1 S120[/c]

No. See the doc I linked to,

vbtalent

So I think I'm ready to autotune and start the process and the power supply shuts down just as soon as it appears to start turning the bed heater on…

The M307 looks good and I didn't think I sent the wrong 303 code so I'm not sure what's wrong. Is there a log somewhere tha tI can see what's causing the PS to sutdown?

https://drive.google.com/open?id=1plW7uU-DcA0oNkPuWwnbLMAWKbM4oQmf

VB,

deckingman

Does the power supply shut down if you simply try turn on the bed heater?

Martin_S

@vbtalent:

OK cool thanks…

[c]M501[/c] ;sets up the writing to the config-override.g

[c]M303 H0 S285[/c] ;I have an E3D hot end, so I assume you would use the max temp?

Then when auto tuning the hotbed simply a change to the max temp something like..
[c]M303 H1 S120[/c]

VB I think that H0 is heated bed by default and H1 hotend.

If you want to PID the hotend you should use a temperature that you normally print, 230ºc for example.
In my case, I also set the amount of power feeded to the cartdrige, which is with the P parameter.

Like this:

M303 H1 P1 S230

if you get an overpowered message from the duet web control you can lower this value a bit.

There is a guide on how to use the autotune, I've already shared it before, but can't find it.

BTW, my bed is currently with bang-bang and it's working ok.
Dunno if it should be calibrated with PID instead

Martin_S

Arghhh….found it:
https://betrue3d.dk/duet-wifieth-pid-tuning-hotend/

and here are all his other guides, builds, tests etc:
https://betrue3d.dk/blog-posts/
Worth spending some time reading them, also check out Ian's (deckingman) blog.
They both have some good tips in there.

vbtalent

Yes, the power supply freaks..

I shot a quick video and noticed there is a a problem that didn't show up when trying to autotune. "Error Short-to_ground on drivers 1 2 3"..
https://youtu.be/a62A1pk6OS0

Below is the config file settings also.

[c]; Thermistors and heaters –------------------------------
M305 P0 T100000 B3974 R4700 ; Bed thermistor
M143 H0 S120 ; Set the maximum bed temperature in c - default is 110c

M305 P1 T100000 B4725 C7.060000e-8 R4700 ; E3D thermistor
M143 H1 S280 ; Set the maximum temperature of the hot-end in c - default is 280c
[/c]

I also tested the resistance on the heater.. not sure what that should read…? I'm a little concerned that it might be shorted out?? The connector for the bed heater can only connect one way so there's no way that is wired up wrong and I connected the +/- correctly to the Duet so...

https://drive.google.com/open?id=1bajDN4pyysa99qAx-zttAH4ZbWLxASFC

VB,

vbtalent

Thanks Martin, I just reread this post and realized I posted the devices backwards.. H0 is the bed and H1 the E3D.

@Martin_S:

@vbtalent:

OK cool thanks…

[c]M501[/c] ;sets up the writing to the config-override.g

[c]M303 H0 S285[/c] ;I have an E3D hot end, so I assume you would use the max temp?

Then when auto tuning the hotbed simply a change to the max temp something like..
[c]M303 H1 S120[/c]

VB I think that H0 is heated bed by default and H1 hotend.

…

Martin_S

VB, regardless of that, you have something else going on there.
Try contacting support.

vbtalent

Martin,

Who’s support Should I be contacting?

Is this a lulzobt issue or a duet related issue?

VB,

vbtalent

Thinking about to how to isolate this problem and I’m assigning that I could use my E3D hotend and connect it to the BED connectors to see if its a BED problem or a Duet problem, would that make sense or would you advise against that idea?

VB,

deckingman

As I understand it, when you try and tune the bed heater, or when you simply try and heat the bed, the power supply voltage drops. Is that correct? If so, it would indicate that either there is a problem with the power supply not being up to the job, or there is a possible short on the bed heater. Using Ohms law, you ought be able to calculate what the resistance of the bed heater should be . If you know the wattage and voltage then you can calculate the current. Wattage is Voltage x Current so to keep the maths simple, if the bed is 240Watt and the voltage is 24v then the current is 240/24 = 10 Amps. Ohms Law is V=IR so R is V/I = 24/10 = 2.4 Ohms. Do the maths for your bed heater then measure the resistance across the heater terminals and see if it's correct. Also check that there isn't continuity between V+ and ground as that would indicate a short. If the heater checks out OK, then the problem is with the power supply (or wiring).

You could try connecting the hot end to the bed terminals but typically a hot end will only have 30 or 40 Watt heater but the bed will be much more so it might not help much.

BTW Heater 0 is the bed and heater 1 is the hot end but it looks like you've already realised that.

vbtalent

@deckingman:

As I understand it, when you try and tune the bed heater, or when you simply try and heat the bed, the power supply voltage drops. Is that correct? …

Correct, simply turning on the bed heater with it wired up causes the power supply to somewhat shut down, not sure how to describe it?

You could try connecting the hot end to the bed terminals but typically a hot end will only have 30 or 40 Watt heater but the bed will be much more so it might not help much.

Will this cause any damage to either the hot end or bed to simply wire it up and turn the heater on its lowest setting to test if its a load issue?

I unwired the heater from the board and simply turned the heater on via the interface. It looks like the voltage output was appx. 24volts on the Duet and the red light came on, so I'm leaning towards the duet being in a good state but without a load on it is that a reasonable assumption?

As for the heater, its a 340 watt 24v heater which I think would calculate into 1.42 ohms based on your example and it actually measures in at 1.2 from the earlier picture I posted.

3 questions come to mind, does it matter the positive and negative terminals of the bed heater since it is essentially a big resister or is there more to it than that, could they be reversed? Also, does the thermistor only play the role of temperature sensor in the puzzle? and does the config.g file have any impact on the type of issue I'm experiencing with the setting I posted earlier?

Thanks.

VB,

dc42

The only part of the bed heater that might be sensitive to polarity is the indicator LED, if it has one; and many bed heaters have two antiparallel LEDs to make them work on either polarity.

What is the specification of the power supply?

Check that the screws on the Duet VIN terminal block are tight..

vbtalent

Finally figured it out with all your help and as usual it was user error.. I failed to check that the power supply was set for 110v it was set for 220v, ugh!!

So I was able to successfully run an autotune on the bed but there are some things I don't understand on the results that were generated.. https://drive.google.com/open?id=1C3dOzSSwoPW5EW1-TuV4BozbI-GM_eyY

Why couldn't I run an autotune with S120 as the heater is rated for 120C?

https://www.lulzbot.com/store/parts/24v-silicone-heater

Why the warning message, is that generic in nature or something to be concerned with?

VB,

dc42

The default bed temperature limit is 110C. You can increase it using the M143 command.

The warning message is telling you that if there was a fault and the heater got left on at full power, it would get very hot. You might want to consider adding a thermal cutout, and/or turn the power supply voltage down a little (and then ~~return~~ retune both heaters).

vbtalent

@dc42:

…You might want to consider adding a thermal cutout, and/or turn the power supply voltage down a little (and then return both heaters).

Thanks Dave, are you saying that you think the bed heater is defective?

Could you elaborate a little more…

VB,

dc42

Sorry, I made a typo and it got auto corrected to 'return' instead of 'retune'.

vbtalent

No worries… thanks for clarifying.