Taz 5 Temperature Drops

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otakuex
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Taz 5 Temperature Drops

Post by otakuex » Mon Jan 29, 2018 11:18 am

I've repeatedly tried and failed to run a 54 hour 400G print. Everything starts fine, but a few hours in the actual temperature drops below the melting point of my eSun PLA and it starts printing in air. I've run the print both from the SD card and from my Octopi. The last time I ran it without filament loaded and took some screen caps to verify the timing, but I think it's a little different each time - I've seen it go for over 8 hours before failing a couple times. At just short of the 2 hour mark it drops from the set 210 to 194. Then at about the 3 hour mark it drops again to 180. By the 4th hour it settles at 184 and stays there for the remaining 50 or so hours. The whole time the target temp still shows as 210 regardless if printing from SD card or Octopi.

I've replaced the heater cartridge to no effect. I've also run it with the bed heater disconnected. I'm running off an APC battery backup with a fresh battery and the Octopi (battery side) and lamp (surge only side) plugged into it don't show any issues, so don't think it's the power source, must be internal.
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Taz 5 w. stock Tool Head V2 0.5mm Nozzle

Galadriel
Aleph Objects | LulzBot
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Re: Taz 5 Temperature Drops

Post by Galadriel » Tue Jan 30, 2018 7:50 am

Have you taken resistance measurements for your thermistor? With the printer turned off and unplugged, disconnect the hot end from the wiring harness and test hot end for the proper resistance. The smaller black and red wires coming from the hot end are for the thermistor and should read ~100k ohms at room temperature. The larger red wires are connected to the heater cartridge and should read ~20 ohms.

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otakuex
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Re: Taz 5 Temperature Drops

Post by otakuex » Thu Feb 01, 2018 2:28 pm

Took some time to get my hands on a reliable multimeter, but the resistances check out. At room temperature I got about 19.9 ohms for the heater cartridge, as well as the old one I had previously replaced, and about 108k ohms for the thermistor.

But I don't think there was reason to suspect it since the displayed temperature drops have coincided with the filament no longer extruding, as it drops below the melting point. I'd say that's a sign that the reported temp is accurate, or at least close enough to not be a problem. I think the issue is with the control board, but IDK what to check there.
Taz 5 w. stock Tool Head V2 0.5mm Nozzle

ScottW
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Re: Taz 5 Temperature Drops

Post by ScottW » Thu Feb 01, 2018 4:00 pm

Do you have any way to capture the console messages? Octoprint has a pretty small buffer, but maybe turning on Serial Logging would capture it all?

It would be interesting to see the temp reports coming from the firmware when the drop occurs (to see what the firmware thinks current target temp is), and whether it correlates with any specific gcode sequence. It really looks like the firmware *thinks* it's temp target was changed, because it drops and then holds pretty steady at a lower level. But Octoprint still shows the higher target, which means it never saw any outgoing temp command in the gcode.

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otakuex
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Re: Taz 5 Temperature Drops

Post by otakuex » Fri Feb 02, 2018 10:33 am

I'll try recording my screen with the console up on one computer while watching the temp graph on another. I'll post some results tomorrow.
Taz 5 w. stock Tool Head V2 0.5mm Nozzle

ScottW
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Re: Taz 5 Temperature Drops

Post by ScottW » Fri Feb 02, 2018 12:13 pm

otakuex wrote:
Fri Feb 02, 2018 10:33 am
I'll try recording my screen with the console up on one computer while watching the temp graph on another. I'll post some results tomorrow.
If that doesn't work out, I just confirmed that Octoprint's serial logging ("Settings, Serial Connection, Log communication to serial.log") captures everything sent/received, and timestamps each entry. There is a warning about the performance hit, but I ran a print with it enabled and didn't see any problems (at least on an Rpi3). File could get pretty big with the hours-long print you're capturing, though.

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otakuex
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Re: Taz 5 Temperature Drops

Post by otakuex » Fri Feb 02, 2018 3:31 pm

ScottW wrote:
Fri Feb 02, 2018 12:13 pm
If that doesn't work out, I just confirmed that Octoprint's serial logging ("Settings, Serial Connection, Log communication to serial.log") captures everything sent/received, and timestamps each entry. There is a warning about the performance hit, but I ran a print with it enabled and didn't see any problems (at least on an Rpi3). File could get pretty big with the hours-long print you're capturing, though.
Perfect! I was looking for this. I'm on a pi3 too, and I'll stop it after 1 or 2 temp drops, so it should be less than 8 hours of logging.
Taz 5 w. stock Tool Head V2 0.5mm Nozzle

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otakuex
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Re: Taz 5 Temperature Drops

Post by otakuex » Mon Feb 05, 2018 10:01 am

See attached Serial.log. It looks like line 7186 (2018-02-04 17:45:10,640) is the last good temp "209.6 /210.0". Then it clearly starts going down at line 7432 (2018-02-04 17:45:16,100). This is when (+/- a few seconds) I saw the OctoPrint temp graph start to drop.

I searched and couldn't find an "S189" commands that might have set the temp to the 189 it settles at. Also no "S186" - "S190". The only hit I got for "S191" was way down on line 11251 (2018-02-04 18:45:27,425) which looks like it was to set the fan speed if I understand correctly. "N5392 M106 S191*83"
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ScottW
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Re: Taz 5 Temperature Drops

Post by ScottW » Mon Feb 05, 2018 12:28 pm

I don't see any reason for the drop, either -- No change in fan operation or extrusion rate, and the firmware still shows the correct target (210) and is applying power as the temp continues to drop. It's like it just suddenly "can't keep up", even though demand didn't change.

Other thing I did notice... is how long it takes to reach temperature. Your initial heatup took over 5 minutes to get to 200c (where printing started) and another 4 minutes after that to finally reach the 210c target. I think my hexagon can go from room temp to 200 in about 2 minutes. That makes me wonder if the heater is getting all the power that's being sent to it. You've already checked the thermistor and replaced the heater, so those are assumed good.

All I can think of to try:
(1) Check your wiring harness and plugs/connectors and crimps, including the plugs at the power supply. Perhaps there's a high-impedance connection intermittently preventing the heater from getting full power.
(2) Compare your PID values (visible in M503, as current M301 values) to those from an AutoTune ("M303 S210"). If they are off by a lot, try setting the autotune values with M301. (I doubt this will help, as it appears the firmware is setting sufficient power level when temp is dropping -- but worth a try if all connections look good).

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otakuex
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Re: Taz 5 Temperature Drops

Post by otakuex » Mon Feb 05, 2018 2:05 pm

Thanks ScottW.
Just to make sure I didn't make a mistake, I recently replaced the thermistor and heater cartridge with the following parts.

https://www.lulzbot.com/store/parts/100 ... thermistor
https://itworks3d.com/product/ceramic-h ... %2F+19+ohm
- 24v/19ohms option
Previously had the heater cartridge direct from Lulzbot and replaced because I suspected it was causing these issues, I still have it as a spare: https://www.lulzbot.com/store/parts/24v ... -cartridge
ScottW wrote:
Mon Feb 05, 2018 12:28 pm
All I can think of to try:
(1) Check your wiring harness and plugs/connectors and crimps, including the plugs at the power supply. Perhaps there's a high-impedance connection intermittently preventing the heater from getting full power.
(2) Compare your PID values (visible in M503, as current M301 values) to those from an AutoTune ("M303 S210"). If they are off by a lot, try setting the autotune values with M301. (I doubt this will help, as it appears the firmware is setting sufficient power level when temp is dropping -- but worth a try if all connections look good).
I'll check the resistances/connections. But, you lost me on 2). Are you talking about writing a custom gcode file? Can you give me a little more instruction or example on that? I haven't done that before.
Taz 5 w. stock Tool Head V2 0.5mm Nozzle

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