What exactly does PID tuning do?
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@phaedrux Sorry m8, missed you were talking about the B parameter. I've changed it and will keep a close eye on temps for a day or two.
Alan
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Ok, for good or for bad, I have ordered the thermocouple daughter board and K type probe for it. I think the reason I didn't want to do that was that I spent a lot of time designing and printing (on another priinter) the case....just the way I wanted it. So now, after installing this, I will be redesigning it again. Oh well.
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So this didn't give a good result?
M305 P1 T100000 B4725 C7.06e-8 -
@phaedrux said in What exactly does PID tuning do?:
M305 P1 T100000 B4725 C7.06e-8
@Phaedrux Pretty much the same results. Now I've tried B4138, B4388 and B4725 and the results have not varied any appreciable amount. All registered around 160 to 170
when DWC reported a temp of 235,
(I also added the R4700 on the end because I figured that was just an oversite that it wasn't added, correct?)@bearer I checked the resistance across the thermiter and it is about 91k which I would think was close enough.
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@crchisholm said in What exactly does PID tuning do?:
I figured that was just an oversite that it wasn't added,
It doesn't matter if it was included or not, but won't hurt to include it.
I would suggest contacting E3D support, perhaps they can replace your thermistor cartridge for you.
Another way to check where the fault lies is to swap the bed thermistor and hotend thermistor connection on the board. If the fault follows the thermistor, the board is fine at least.
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@bearer I checked the resistance across the thermiter and it is about 91k which I would think was close enough.
If your ambient temp is about 27C then that should be correct.
(if https://e3d-online.com/100k-ohm-ntc-thermistor-semitec is correct and it is a 104GT-2 (which is replaced by 104NT-4-R025H42G) both should have b=4267 from what I could tell )Try another input on the Duet?
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@crchisholm said in What exactly does PID tuning do?:
The problem is worse than I thought. I tested the thermocouple/multimeter with boiling water and it was within a couple degrees of 100c. I taped the thermocouple to the heat block and when DWC showed 235c , the thermocouple showed 160c My neighbor has another thermocouple device and we tried with that and got essentially the same reading (157-165)
It's hard to get a good reading that way, because the thermocouple leads carry heat away from the top and it's difficult to get good thermal contact with the heater block. Even so, that difference in reading is greater than I expect. So I think the thermistor may be faulty.
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I am going to put this on hold for the time being. Appreciate all the input and assistance. I have ordered the thermocouple and daughter board and will see what that brings to the game. As it stands now, I can get some pretty good prints (I've only used PLA thus far) just by jacking up the temp.
I actually think one or the more fun aspects of this pursuit is trying to be as smart as the machine. Not there yet, but who knows....
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@crchisholm said in What exactly does PID tuning do?:
I actually think one or the more fun aspects of this pursuit is trying to be as smart as the machine.
I couldn't agree more.
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I may be hijacking my on thread, but would like to ask an unrelated question. Is there a G or M code that would lock the motors (especially Z). I keep moving the bed down by accident when working on there parts of the printer, and then have to relevel. Aggravating!
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@crchisholm said in What exactly does PID tuning do?:
I may be hijacking my on thread, but would like to ask an unrelated question. Is there a G or M code that would lock the motors (especially Z). I keep moving the bed down by accident when working on there parts of the printer, and then have to relevel. Aggravating!
Are your motors using idle current at that point?
Combination of M84 and M906 to set current.
https://duet3d.dozuki.com/Wiki/Gcode#Section_M84_Stop_idle_hold
https://duet3d.dozuki.com/Wiki/Gcode#Section_M906_Set_motor_currents -
@phaedrux
Ok, does this look like the correct stratigy?Created a macro 010_Freeze_Z_Axis with the following lines....
M84 Z
M906 Z:300
...assuming the motors are 1a and I only want to freeze Z. -
Not exactly.
M84basically turns the motors to a lower power mode so they are quieter and can cool off. So where you haveM84 Z, that will basically turn the Z motor off, which is the opposite of what you want.M84 Snsets the timer for how long it will sit idle before going to lower power. The amount of current used for this is set byM906 Inwhich is a percentage of the normal current. So you'll want to set the amount of current to a level that will still keep the motor from turning when you press on the Z axis. Or alternatively, increase the idle time out so that the motors stay fully powered for longer, and therefore keep their holding power.So maybe for you the best setup would be
M84 S600 ; set idle timeout to 10 minutes M906 I50 ; set idle current to 50% of normal -
@phaedrux I will try that. Thank you very much.
This mornings challenge seems to be understanding the M557 code to set the probe grid. Getting closer. Still getting results other than intended, but I guess that's to be expected when you don't expect the right thing.
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@crchisholm For the M557 it's important to keep the probe offset specified in the G31 command in mind when determining the grid extents.
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@phaedrux ahhhh.... So when I enter the cordinates into the M557 command, am I entering the coordinates of the probe or the tip?
I'll bet that is where I am going wrong.
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@crchisholm said in What exactly does PID tuning do?:
@phaedrux ahhhh.... So when I enter the cordinates into the M557 command, am I entering the coordinates of the probe or the tip?
I'll bet that is where I am going wrong.
They are the coordinates of the probe.
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Ahhh....that explains why It would skip anything less than 30 in the X direction. My offset is X30 Y15. Should have figured that out. Thanks.
