Hot end temp issue???

[TKCC71]

Cant seem to figure out why my hotend hovers 2-3 degrees below the target temp. If I set it at 230 it will go to 228, If I set it a 245 it will go to 243. The problem I'm having is it wont reach the target temp for the print to start. Ive taken the hotend whip on an off and inspected the wires and no issue. I also built the secure clamp to keep the whip attached and still the same problem. Any thoughts on what could be causing this before I go and tear the hotend apart and re-wire the whole thing and put in a new thermister?

[IMBoring25]

If you did re-wire the whole thing you would be disappointed. You just have bad PID settings and rewiring won't solve that. You can try another autotune or you can start by trying to manually tweak the tune you have. The brute-force method for this problem would be to increase the P parameter, maybe starting with 20%, and see what that does.

[TKCC71]

Thanks I will go ahead and give it a shot. Heres my values the came up in the calibration. KP 33.10, Ki 4.73 and KD 57.88

So when I go back into the communication panel do I run M301 and then the values followed by a M500?

I tried doing that but kept getting a invalid command. You wouldnt happen to know correct way to type that in would you?

[TKCC71]

Ok, definitely has not solved the issue. Raised it 20%, temperatures are still fluctuating below the target. My prints will start out fine on the first couple of layers and then I get the dreaded DEF on the LCD for the extruder and bed and its printing in dry mode? Im really wondering if this is a bad thermistor. I dread tearing this apart. Any last suggestions??

[moo77777]

After your first couple layers does the part fan turn on? I find the default part fan to give too much cooling and actually cools my base down enough to cause the dreaded DEF you are seeing.

[TKCC71]

It actually does turn on on the 3rd layer. I will try it again with no fans and see what happens.

[TKCC71]

Seems to be printing ok now, thanks that may have been the culprit. I completely turned the fans off. it's a 10 hour print job so will have to see if makes it through the night. If that is the problem how can you adjust the firmware config so it doesn't shut down running those fans?

[bludin]

I have a similar problem here with my stock MAX v3:
The HE280 temp is always a few degrees too low, so print jobs never start unless I preheat manually a few degs above print temp. Also, when working at 255°C (with PCmax, great material), the temperature drops like 15°C at higher extrusion rates (often resulting in the a false thermistor misread error and communcation shutdown.

I've tried a M303 S255 and I see some improvement, but not satisfactory, so I'll probably have do tune manually.

How do I (via the terminal, since I run Octoprint) set and save the PID parameters?

Where can I find documentation for these things. I find bits and pieces here and there but nothing that is really conclusive.

Also, my hotbed doesn't get past 83°C. Does anybody know what the problem could be? (I've verified that the thermistors are reading the correct temps).

Thanks for anybody willing to help a newb

beat

[iKeyborg]

I have a similar problem here with my stock MAX v3:
The HE280 temp is always a few degrees too low, so print jobs never start unless I preheat manually a few degs above print temp. Also, when working at 255°C (with PCmax, great material), the temperature drops like 15°C at higher extrusion rates (often resulting in the a false thermistor misread error and communcation shutdown.

I've tried a M303 S255 and I see some improvement, but not satisfactory, so I'll probably have do tune manually.

How do I (via the terminal, since I run Octoprint) set and save the PID parameters?

Where can I find documentation for these things. I find bits and pieces here and there but nothing that is really conclusive.

Also, my hotbed doesn't get past 83°C. Does anybody know what the problem could be? (I've verified that the thermistors are reading the correct temps).

Thanks for anybody willing to help a newb

beat

I think you need to install http://plugins.octoprint.org/plugins/eeprom_repetier/

I did not try it but it should work

I set Kp = 55.7, Ki = 11.8, Kd = 65.5, it always passes 240 and stable. I did not try 255.

For the hotbed I covered bottom side of it with layer of Kapton which creates still air thermal insulation.
The fan from power supply cools down the hotbed.

Warm up your house or add enclosure to you printer.

[bludin]

Thanks for the good advice, iKeyborg. Very good point about the bed being cooled by the fan.
The plugin works, but it seems that it is only changing one parameter at a time or unreliably, so I always check by loading from trhe EEPROM after writing to it.

Your PID parameter values do not really change much, i.e. the temperature still remains too low and goes further down upon extruding.

Do you (or anybody else) happen to know what the following parameters do?
Extr.1 PID drive max
Extr.1 PID drive min.
Extr.1 PID max value

[iKeyborg]

Thanks for the good advice, iKeyborg. Very good point about the bed being cooled by the fan.
The plugin works, but it seems that it is only changing one parameter at a time or unreliably, so I always check by loading from trhe EEPROM after writing to it.

Your PID parameter values do not really change much, i.e. the temperature still remains too low and goes further down upon extruding.

Do you (or anybody else) happen to know what the following parameters do?
Extr.1 PID drive max
Extr.1 PID drive min.
Extr.1 PID max value

I don't know about Extr PID parameters, this is extruder motor control I guess.
Regarding Hotend, I suspect the heater cartridge power is not sufficient.
If you see not blinking hotend red indicator your cartridge is at max power.
I see some temperature drop even at 240C (about 1 - 1.5C) during fast printing. To get to 260C the heater cartridge should produce 10% more heat. If you can manage to increase 12V PS output to 12.6V it will give you 10% temperature rise. I will try it on my machine tonight. I don't know if it is safe for the cartridge.

[Polygonhell]

Thanks for the good advice, iKeyborg. Very good point about the bed being cooled by the fan.
The plugin works, but it seems that it is only changing one parameter at a time or unreliably, so I always check by loading from trhe EEPROM after writing to it.

Your PID parameter values do not really change much, i.e. the temperature still remains too low and goes further down upon extruding.

Do you (or anybody else) happen to know what the following parameters do?
Extr.1 PID drive max
Extr.1 PID drive min.
Extr.1 PID max value

PID Drive max is the maximum value for the PID drive to the hotend, 0-255, 255 is always on, if it's set to say 127 then they heater will never run more than 1/2 the time.
PID Drive min, is he minimum PID setting while heating I'd leave it at 0 unless you have a good reason not to, it can be used to stop wild oscillations around a temperature.
PID max value is I believe the maximum PID value the PID calculation can return, this is separate from the P Gain.

Short version is if you can't reach temperature, ensure Pid drive max and Pid Max are 255, increase the P gain a bit and reduce I and D.

[bludin]

Thanks polygonhell and iKeyborg. That's what I needed.

So now I have
- cranked up my power supply to 12.8V (was 12.2V)
- increased PID drive max to 255 (was 180)
- decrease PID drive min to 0 (was 80)
- set my PID to 35/7/15

... and now my extruder temp. is stable at 259.7°C, even when extruding fast.

[iKeyborg]

Thanks for the good advice, iKeyborg. Very good point about the bed being cooled by the fan.
The plugin works, but it seems that it is only changing one parameter at a time or unreliably, so I always check by loading from trhe EEPROM after writing to it.

Your PID parameter values do not really change much, i.e. the temperature still remains too low and goes further down upon extruding.

Do you (or anybody else) happen to know what the following parameters do?
Extr.1 PID drive max
Extr.1 PID drive min.
Extr.1 PID max value

PID Drive max is the maximum value for the PID drive to the hotend, 0-255, 255 is always on, if it's set to say 127 then they heater will never run more than 1/2 the time.
PID Drive min, is he minimum PID setting while heating I'd leave it at 0 unless you have a good reason not to, it can be used to stop wild oscillations around a temperature.
PID max value is I believe the maximum PID value the PID calculation can return, this is separate from the P Gain.

Short version is if you can't reach temperature, ensure Pid drive max and Pid Max are 255, increase the P gain a bit and reduce I and D.

Thank you Polygonhall,
Very useful information,
I will open up my PID max and drive max to 255 as well to give more room to the heater.
There is a good PID parameters explanation on https://www.repetier.com/documentation/ ... tallation/ in chapter "Extruder configuration"
I think for 260C an optimal value for drive max is 220 but 255 will work as well with slight overshooting. Looks like 12.8v is not needed for the hotend but usefull for the bed.
Correction: I set PS in my printer 12.8v to keep hotend at 240 with 100% object fan. 12v is not enough.

[sfuelberth]

Just because I recently conquered a problem like this, I recommend this thread for a good summary on the PID controller: http://forum.seemecnc.com/viewtopic.php ... 27#p101827