MatterControl 1.6 extruder controls temp 5 degrees too high

[rootboy]

Hi guys,

I've got this issue with MatterControl 1.6. If I set my extruder setpoint to 200 degrees, MC will do a very nice job of maintaining the temperature at 205 (and report it as such). Setting it to 210, will cause MC to heat it to 215. 230 ends up running at 235, and so forth.

And it *knows* that it's 5 degrees off! It's cheerfully (spitefully) setting the output 5 degrees higher regardless of what my desired temperature is.

This causes MC to overshoot the setpoint by 5 degrees and not start the print.

Tuning the PID has no effect on the 5 degree offset. I'm a Controls Engineer, and I've got to hand it to the guys who came up with the PID algorithm, it is top notch. Other than the 5 degree offset, that is.

So what I've done is tune the PID (obviously), and I diddled with the gains when that didn't work (it may over or under shoot, but it always settles in at +5 degrees over).

I'm using a Rostock V2 with a Prometheus Hot End. 1.75mm ABS, and the stock EZtruder. I had the same problem with the stock V2 head before I switched to the Prometheus head.

And please, before we get into how accurate my thermistor may or may not be, let's not lose sight that however bad it may be, MC wants to run it 5 degrees hotter.

So is there a place in the firmware where I can put an offset?


Thanks!

John

[pouncingiguana]

Does this only happen in mattercontrol? What happens if you set the temperature manually on the LCD?

[geneb]

Rootboy, MatterControl doesn't really do what you think it does. MC can only tell the printer to heat to a specific temperature and will report the ongoing temperature values that the printer sends back to MC. If there is a temperature control issue, it's going to be living in the printer controller.

As suggested, try setting the temp from the front panel and see what you get.

g.

[rootboy]

Thanks guys! I'll try that. Just for grins I installed Repetier and it had no problem with controlling the temps.

I did get it to print straight away by setting my manual temp 5 degrees below what it was going to print at and then telling MC to start printing once it got within range. It worked like a charm.

Oh, and I'm using the Repetier-091-ROSTOCKMAX-master firmware with the only modifications to the Config.h being the define printer value (2), and inverting the extruder direction (I was too lazy to re-wire it).

And it's odd, but I checked the "Notify me when a reply is posted", but I didn't receive an email...


Thanks again!

John

[Mac The Knife]

I'd stick with Repetier. Myself, I use Simplify 3d. I tried Mattercontrol when SeeMeCNC dumped Repetier and started pushing mattercontrol. It seemed like every update broke another feature, and the update to fix that broke another. Last I looked, I see that they make it convenient to order products from them through mattercontrol.

[rootboy]

I've used Repetier, and it's okay. I like the simplicity of MC. And setting my pre-heat temp to 10 degrees below what the printing target will be starts things off just fine. We can label this one solved I guess.

[Mac The Knife]

I'd call that a band aid.

[geneb]

What I don't get is the differing behavior. Unless the MC guys are pulling some kind of stupid stunt with the temperature setting mechanics, the only thing it should be doing is issuing the M code for setting the temp. As long as it's connected to the printer, it'll be reading the temp values that the RAMBo continually sends back, and that won't affect the heater temp.

g.

[rootboy]

Sorry about not responding before, I didn't see an email notification for your replies.

@Mac The Knife: Yup. That's what I would call it too. And PID loops are pretty integral to what I do for a living, so it's got me perplexed too. It's like it has a built-in offset...

But I set the pre-heat temp about 10-15 degrees below what I'm going to have MC print at, and once the bed heats up, it's a short jump to where the head needs to be and it almost always takes right off.

Currently my thermistor has gone south so I'm waiting on a new one to arrive.

[hcdbey]

I am experiencing the same problem. The hot end temperature overshoots the target and does not return to the target.

Printer is Rostock Max V2 with original hot end. Software MatterControl 1.5.3

Autotune run three times now with similar values each time.

The overshoot behavior is the same regardless of whether I set the target temperature via MatterControl or on the printer's LCD display panel.

If I set the target to 200, the temperature rises to 212 and then slowly settles back to 208. It stays at 208 indefinitely.

In order to start a print, after it reaches 208, I set the target to 0 degrees. Then I wait for the temperature to fall back to 201 degrees or there about and press "Print". During the printing of the skirt, the temperature falls to 190 degrees and before the actual models starts to print, the temperature again goes to 212 degrees and then falls back to 208 degrees, where it stays through the duration of the print.

Any suggestions as to what might be causing this?

[Xenocrates]

Try adjusting your I-gain, and see if that affects your offset. Autotuned PID loops are not perfect, and some amount of hand adjustment is often helpful. Try some drastic changes with it, halving and doubling, to see what direction you need to go in, then fine tune. This should also reduce your overshoot. Your other PID terms may need to shift as you adjust I, however. Try using something like Octoprint to graph your temperatures, so you can see how they behave better.