HotBed Heating Too Slow?

A Former User

Yeah, so, I've been dealing with this since last evening. I've read everything I can find, with almost no luck. I've searched this forum without luck. So, DWC keeps telling me my HotBed is heating too slow. It was expecting about 2.36 degrees c per second, and it was getting .015 degrees c per second. Initially, the problem was the signal wires coming off the bed were DOA, so I resurrected an old connector, tested it to make sure the wires were good, then put that on. The bed is from an old Anet A8. My guess is: the thermistor is a NTC 3950. So, I went through the process. I've generated a new config.g file about five times now. We tried PID for the bed setting, then we went back to bang-bang, then we discovered you could select the thermistor (what a surprise that was), so we chose the cheapest one thinking that would solve our problems. We also tried switching the wires, but thermistors don't need that.

So, any thoughts of what's going on? I've put the code for the bed and the hot end below. The HotEnd is heating up fine.

M308 S0 P"temp0" Y"thermistor" T10000 B4100        ; configure sensor 0 as thermistor on pin temp0
M950 H0 C"out0" T0                                 ; create bed heater output on out0 and map it to sensor 0
M307 H0 B1 S1.00                                   ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0                                            ; map heated bed to heater 0
M143 H0 S120                                       ; set temperature limit for heater 0 to 120C
M308 S1 P"temp1" Y"thermistor" T10000 B4100        ; configure sensor 1 as thermistor on pin temp1
M950 H1 C"out1" T1                                 ; create nozzle heater output on out1 and map it to sensor 1
M307 H1 B0 S1.00                                   ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S240                                       ; set temperature limit for heater 1 to 240C

jay_s_uk

@mac PID tune the bed using M303 H0 S60

TechMav

I had the same issue. You need to run a PID tuning cycle on the heat bed and put the resultant code into your config.

https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

TL;DR
You need to run
M303 H0 S60

(H0 is the bed heater, change if needed, and S60 tells it to take the bed to 60C, change as needed)

It may take upwards of an hour plus to run. It'll output an M307 code line, that you need to put into your config.

Rushmere3D

@mac if you think it's a 3950 thermistor, I would set that as the thermistor and not how you currently have it.

And without trying to be rude, can you not post new thread after new thread, this is all for one printer yes? One thread will ALL your issues in would be a lot easier to help with.

A Former User

@rushmere3d no one’s been that clear. Thanks; I’ll make this the one and only thread of my issues and experiences from now on.

Phaedrux

@mac said in HotBed Heating Too Slow?:

@rushmere3d no one’s been that clear. Thanks; I’ll make this the one and only thread of my issues and experiences from now on.

Well... within reason. Eventually threads can get so long that it can become difficult to follow or get caught up. Having ten issues in a single thread with a title that's unrelated to all of them isn't great either, because then people may skip over the thread title and not see your actual issues.

Since you're just getting up and started with Duet it's understandable you have a lot of questions as things arise. Maybe try and keep it to one thread for each major issue and keep related questions there.

Rushmere3D

@phaedrux I certainly think a thread titled appropriately with one complete set of config files would be far better than random threads with little context.

Also makes it easier for people looking for answers to questions already asked.

Phaedrux

@rushmere3d said in HotBed Heating Too Slow?:

@phaedrux I certainly think a thread titled appropriately with one complete set of config files would be far better than random threads with little context.

Also makes it easier for people looking for answers to questions already asked.

Yes absolutely. But eventually the config changes and problems are solved and it's 200 posts long. So eventually a fresh start is helpful.

Rushmere3D

@phaedrux eventually yes, once most issues are addressed. Anyway back to getting another duet user going hey.

A Former User

@techmav thanks for the treatise on PID turning.

Ah, what does PID stand for?

I have zero experience with communicating via gcode. If fact, I don't like the idea of converting thoughts / language into code for the purposes of communicating. On the other hand, I recognize that using code to lump a bunch of ideas together works. But a long doc full of code-speak, none of which says "this is how you actually do this," well . . . that's rough. I get it that one needs to do this, but jeeze-louise, it's tough of noobies.

So here's what I know: at the top of DWC (I'm using code to shorten this up), there's this long line that starts with "Send code . . ., after which there's this blue box with an arrow pointing right, and the word: Send. Are you suggestion I type something into that box, and send it to my printer so it can do PID tuning? This is the stuff I'm missing in a lot of the advice and recommendations I'm getting. And because I don't get the fundamentals, the advice is lost on me. We're all wasting our time. What might be better? Someone saying, "Type the following into that line on the top of your DWC. Send what you typed to the board. Wait for the board to process the information. When it's done, look somewhere, and copy that information (somehow), and put it in your config.g file (somehow). That's what I'm getting from reading your wonderful, informative post, and skimming down the pages and pages you sent me (that you, by the way, that was very helpful long term).

Mac

A Former User

@jay_s_uk read a bunch of these posts, decided to give your striaght-forwards reply a shot. Thank you. Mac

TechMav

@mac

TL;DR

In the web interface, click on Console on the left.
Just below the grey boxes at the top, labeled Status, Tools, and Temperature Chart, there is a blank space with a blue box to the right that says "Send"
In that box, you will need to enter:
M303 H0 S60
and click Send. This will run the PID tuning cycle. It may take up to an hour.

Once it finishes, you will see an output below it with an M307 line in it, something like:
M307 H0 R0.579 K0.295:0.000 D2.99 E1.35 S1.00 B0
Copy from M307 to the B0 at the end.
On the left, click on System, then click on config.g. This will open the config file for the printer in an editor.
Find the line in the "Heaters" section that starts with M307. Replace that line with the line you copied.
Click Save at the upper right, and it will ask if you want to reload the motherboard or run the config. Either will work to apply the change.

Background info:
PID stands for proportional–integral–derivative. It's a control loop that takes into account (in this case) how fast the print bed heats up and cools down, so it can modulate the heating to keep it stable, rather than the 'bang-bang' approach which turns the heat full on or full off. PID tuning lets the system figure out what heating rates to expect instead of the default values that may not apply.
I was having the same issue, my print bed is a 12" x 12" x1/4" aluminum plate, and was heating at about 0.3C/second instead of the 1.7C/sec the system was expecting.

A Former User

@techmav thanks for coming back with that recipe for action. it's going to be the first time I edit my config.g file! Mac

A Former User

@mac process update: DWC cancelled the process because the temp wasn't reached (in an appropiate time?, DWC didn't say). So, can I S40? Because just before the cancel happened, the bed was as 43.9.

A Former User

@rushmere3d did that in a subsequent config.

Phaedrux

@mac said in HotBed Heating Too Slow?:

Ah, what does PID stand for?

proportional–integral–derivative

https://en.wikipedia.org/wiki/PID_controller

A Former User

@phaedrux there's got to be a joke in that acronym somewhere!

Phaedrux

I thought so too, and I could get close, but never quite reach it.

A Former User

@phaedrux I've never meant a proportional integral I didn't find derivative.

A Former User

@techmav

6/23/2022, 3:01:49 PM Warning: Auto tune of heater 0 failed due to bad curve fit (R=0.129 K=2.291:0.000 D=2.92)