Hey look, another PID Autotune problem...

[barry99705]

Got the printer built, made it all the way to the extruder calibration and hit a wall. Keeps failing for temperature too high. Changed the eprom settings to 128, still shoots right past 200c. Any clues?

[geneb]

Set it lower.

g.

[barry99705]

What's the lowest I can set it? 100 just failed.

[barry99705]

Aaand 80 just failed.

[barry99705]

Set it to 60, doesn't even slow down when it gets close to 200, just bops right on by. As far as I can tell the thermistor is working, it's says the same temp as the bed plate when everything cools back to room temp, and they're a couple degrees off from the furnace thermostat on the wall 6 feet away.

[Polygonhell]

Which value are you setting?
And what are your current PID settings for extruder 0 in the EEPROM?

[barry99705]

Which value are you setting?
And what are your current PID settings for extruder 0 in the EEPROM?

Changing Extr.1 pid drive max. I don't have an extruder 0 in the eeprom settings.


Also just found if I turn the dial on the front, one way does nothing, the other resets the board. Pretty sure that's not right!

[Windshadow]

Barry are you using the current version of the manual? if your LCD has a red circuit board it can get into a reversed mode the date on the cover of the manual for a December shipped kit should be like this

Welcome to the Assembly Guide for the Rostock MAX v2.0 3D printer. Version 4.14, December 29th, 2015
Fourth Edition

m JJ sent me this via email

Is the LCD screen still working backwards? There is a variable in the firmware to change for that. We have had a recent hardware change so the rotary dials now work opposite as they used to... . Here is a blog post about this change: http://www.seemecnc.com/blogs/news/8169 ... re-changes" onclick="window.open(this.href);return false;

note to read the blog post mentioned in the screen shot below click the link above
[img]https://p4.zdusercontent.com/attachment ... xSFLCd9WCg[/img]

[barry99705]

Barry are you using the current version of the manual? if your LCD has a red circuit board it can get into a reversed mode the date on the cover of the manual for a December shipped kit should be like this

Welcome to the Assembly Guide for the Rostock MAX v2.0 3D printer. Version 4.14, December 29th, 2015
Fourth Edition

m JJ sent me this via email

Is the LCD screen still working backwards? There is a variable in the firmware to change for that. We have had a recent hardware change so the rotary dials now work opposite as they used to... . Here is a blog post about this change: http://www.seemecnc.com/blogs/news/8169 ... re-changes" onclick="window.open(this.href);return false;

note to read the blog post mentioned in the screen shot below click the link above
[img]https://p4.zdusercontent.com/attachment ... xSFLCd9WCg[/img]

Yep, using the latest version. Also did those changes.

[barry99705]

Okay, so I set the target to 100C, it will bounce to around 104, then drop to 100, then back up to 104. That looks about right to me. If I manually set it to 100C it will jump to 216, then start hovering around 200, also looks right. The pid autotune routine will hit 220 when it fails out.

[Xenocrates]

sounds like a combination of too high an initial P (reduce your P value a bit) and a conservative hotend max temp. Bump it up to 230, 235 maybe. Do be careful though, as 235 is cutting it a bit close.

[barry99705]

Think I got it. I used the pid values in the manual as a start, set the drive max to 100, if I use the default setting it fails, even with the new pid values. If I use the new pid values from the finished autotune, then run a second autotune it fails... Going back to the numbers from the manual works though, so I'm going to keep that for now.

Oh, and the knob not working right was a backwards B cable...

[jdgraham]

I seem to be at the same stage and have the same problem. After some experimenting I changed the PID max value [0-255] to 205. This is keeping the extruder from overheating and I am getting PID values close to those in the manual. Can someone point me to a glossery of the EEPROM Settings so I can know what I am adjusting? Thanks.

[blackrabt]

I had this problem and changed my extruder heat manager to dead-time. http://www.repetier.com/dead-time-control/" onclick="window.open(this.href);return false;
It might work for you, mine is doing fine like this.

[knabo]

I have the same problem. Nothing seems to make any difference with the PID control. The heater drives to 200 and then turns off. Once the overshoot hits 220 the PID tuning shuts down. Yes I am saving the EEPROM data, etc. I can reload the EEPROM and my numbers are there. Switching the Extruder Heat manager to 3 and using the dead-time control works well.

The BED control works well enough.

[knabo]

OK, so I played some more with the PID system. I can get the autotune to work if I set the PID max value [0-255] to 205. This number seems to be the PWM setting, so 255 runs 100% 205 is about 80% power. With this setting the overshoot does not hit a limit and the PID can be calculated. This is what I got: P=14.18 I=.73 D=68.45

Ultimately I set the PID max value back to 255 and gave the heater a setpoint. I had about 10 degrees of overshoot and after a few minutes of ringing it leveled out to 200 +/- 1 degree.

Not great, but at least the system seems to be working.

I will try to fine tune some more when I get the PEEK fan installed. Then I will be able to perform a better comparison with the Dead time control solution.

[CDRELXIV]

Hey look, exactly synchronised builds I finished assembling my printer last night, struggled with calibration settings for the hotend this morning (same issues as you, the calibration manual's suggestion to drop the Ext Driver Max setting to 128 wasn't enough on its own, had to drop the Ext Max setting as well), the fan shroud is printing as I type this so I can try again

[Qdeathstar]

I had this same issue, and resolved it by changing an additional setting in eeprom but can't remember what it was... The pid works now, but still seems to overshoot more than my Prussa.

[knabo]

After installing the PEEK fan the PID routine would complete without faulting. There is still about five degrees of overshoot or so but once that settles out the temperature holds pretty stable.

I am sure there is a reason for omitting the Bed heater PID autotune from the instructions, but just in case you want to dial that in:

M303 P1 S60

Takes a while to complete of course.