Spurious heater faults and how to avoid them
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I've been having faults during prints. Its all sporadic, but the time I saw the error it was an excursion error that said the temp changed by more than 10C. I just changed my config.g file to allow up to 20c change and I wrapped my heater block in kapton (I have no other forms of insulation).
I was using an E3D hotend in my Kraken for a while and I recently switched to one of my volcanoes. I'm still not sure why, but I had 0 issues with the E3D. Some differences I noticed are the silicone sock I made for the E3D block, and theres a recent issue with my water cooling setup leaking, but I changed the tubes this morning and it still had the problem. I'm hoping its just an issue with when the AC in my apartment kicks on and that this kapton will fix it (I also added 1/3 of a chamber on the side of my printer to try to eliminate some drafts). I'll post whether this appears to fix my issues or not.
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Turns out it was just a wiring issue, one of the crimps wasn't properly done.
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For multiple extrusion with a duel Chimera type hot end, the biggest overhead is that,
on every layer, hot end 1 has to cool down to standby temp, while hot end 2 heats up from standby temp to working temp.
So the objective is
a) Have minimum difference between standby and working temp.
b) Take minimum time for cool down and heat up process.
Can this be achieved when PID tuning is enabled or would i be better off going back to the 'old' way of working?
I'm using 24V, 37W heaters
Thanks -
For multiple extrusion with a duel Chimera type hot end, the biggest overhead is that,
on every layer, hot end 1 has to cool down to standby temp, while hot end 2 heats up from standby temp to working temp.You should not be waiting for the active hot end to cool down to standby temperature, just for the new active nozzle to heat up (which takes less time on most systems). The M116 command has optional parameters specifically so that you can achieve this.
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The PID tuning aims to prevent significant overshoot at the expense of approaching the target temperature more slowly than is possible with more aggressive parameters, that said you can modify the parameters to meet your needs. If you are ok starting printing without the temperature stable then you can be more aggressive.
When I was experimenting with chimera I found it was the cool down time that limited the tool change speed rather than the warm up but that was ages ago before PID tuning in the Duet. I ended up making holes in the M90 fan duct to blow on both heater blocks so that they cooled down quicker, even though that meant they heated up slower.
Cheers
Tony
Edit, David got there first
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When I issue a M562 H1 I am able to clear the fault, but it doesn't seem like the web interface turns on the heater once I set the temp back up.
It will show it being set to 230, but the temps act like the heater is off
Using v1.16
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You need to re-select the tool, e.g. send T0.
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Hi. This is should be a simple question and i think i already know the answer. I am printing a very small part and need my fans running at max and when they first come on they knock about 20c off the hot end temp, so i think just for this small part i want to increase the fault delay so i can get the part printed….
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Best bet is to ramp up the fan speed, do it before the print starts if you absolutely need 100% even on the first layer.
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Tuning the heater with the fan fully on may also help.
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I am seeing theese spurious temperature faults. First I started getting them after installing a fan for printing PLA but limiting the fan speed resolved that.
Now I am getting them again when printing nylon at 260C (no fan). I have autotuned the PID regulator to 270C.
The resulting PID paramters I am using is M307 H1 A383.6 C190.7 D7 B0. Do theese look sane?The termistor is configured as M305 P1 T100000 B4388 R4700 H0 L0 and is supposed to be a Semitec 104GT2 thermistor from e3d (I am pretty sure it is since I got it from a reutable vendor).
I have tried to change the fault time to 20s , M570 H1 P20 T15, but I still get faults and I dont really want to go further.
One interesting thing is that it pretty much always happens at the same time. All the failed objects look the same. It is after switching from infill to a printing a top layer. On the other hand I have tried extruding as much as possible and watching the temperature and it does not drop more than 5C ever.
Any idea what to try? Do I need a thermocoupler? A better thermistor?
All help is greatly appreciated!
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That D parameter looks rather high. Try reducing it to 4 or 5. If that results in temperature oscillations, increase it again. Make sure that the fan is directed at the print, not at the heater block. Also, putting a silicone sock over the heater block will help shield it from the fan.
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Thanks for replying. I tried setting D to 4, still get a fault at about the same time. Curve looks stable.
Just to clearify, this is without any fan at the nozzle/heat block. Any other suggestions? -
Have you used M143 to increase the maximum allowed temperature? The default may be too low for Nylon.
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M143 returns:
Temperature limit for heater 1 is 330.0CThats a pretty wide margin.
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When the fault occurs, what is the error message sent to the console?
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I get the "temperature excursion exceeded 15.0C" message.
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I've been noticing an interesting temp spike, so far only during the initial heating ( though I suspect it also happens during a print ). For no clear reason I'll get a spike to 2000 ( or whatever, its hitting the max chart area ) for a reading or two and then settling back to a normal reading.
I was reading up on https://duet3d.com/wiki/Spurious_heater_faults_and_how_to_avoid_them#Faults_when_maintaining_temperature
and I think I have either a bad connection or noise in the line. What can I do to diagnose which is occurring?I'm using the pt100 board and an e3d pt100. I made a modified pigtail adapter to go from the e3d connector to another I use. I also break out from 2 to 4 wires at that pigtail, switching over to stranded hookup wire for the duration of the run ( ~600mm of cable ). The pigtail itself is only a few inches long, just enough to make the 2-4 jump and connect to my wiring harness.
As best I can tell I have solid connections everywhere. Is the pigtail to 4 wire a good or bad idea? The docs I had read suggested switching to the 4-wire as close to the sensor as possible which is why I went this route. I'm debating doing a 2-wire run from the pt100 to the controller and then just have a little jumper between the pair and the extra connector for each side.
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Similar to what I was reporting here.
My spec was:
Standard Thermistors (rather than PT100)
Duet 0.6 (Ethernet connection)
E3D Titan Extruder
E3D V6 hot end heater unconnected at test)
Two z-axis steppers
Axis Stepper Motors: JK42HS34-1334AIt appears to be a spike with no duration when I saw it.
In short until we have shielded stepper cables and earth bonding for the frame and motors the most likely cause appears to be noise or static build up.
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I've been noticing an interesting temp spike, so far only during the initial heating ( though I suspect it also happens during a print ). For no clear reason I'll get a spike to 2000 ( or whatever, its hitting the max chart area ) for a reading or two and then settling back to a normal reading.
I was reading up on https://duet3d.com/wiki/Spurious_heater_faults_and_how_to_avoid_them#Faults_when_maintaining_temperature
and I think I have either a bad connection or noise in the line. What can I do to diagnose which is occurring?I'm using the pt100 board and an e3d pt100. I made a modified pigtail adapter to go from the e3d connector to another I use. I also break out from 2 to 4 wires at that pigtail, switching over to stranded hookup wire for the duration of the run ( ~600mm of cable ). The pigtail itself is only a few inches long, just enough to make the 2-4 jump and connect to my wiring harness.
As best I can tell I have solid connections everywhere. Is the pigtail to 4 wire a good or bad idea? The docs I had read suggested switching to the 4-wire as close to the sensor as possible which is why I went this route. I'm debating doing a 2-wire run from the pt100 to the controller and then just have a little jumper between the pair and the extra connector for each side.
Yes the pigtail to 4 wires is a good idea. Most likely the wires are picking up interference from stepper motor or (just possibly)) heater in the same cable run.
