Heater faults, but rarely

[Veti]

the one with the screw or the one with the cartridge?

[brandonh]

@Veti (edited because I totally misread this) i'm using the screw-held thermistor. Got about two years on this one with no changes.

Also - I think I've got a good next step - re-run the same gcode file with no fan and no filament to rule out any effects there (like changing cooling as the print builds)

[Veti]

try loosening the screw a tiny bit.

[brandonh]

@veti What would loosening the thermistor screw do?

[brandonh]

Update:

I tried jiggling the board-to-effector cable and the effector crimp cable for the thermistor, and I could not see any evidence of the problem seen last night. That makes me think that nothing from the effector up is relevant. I unplugged and replugged the thermistor plug (connecting the effector to the thermistor) too. Now the problem seems to have gone.

I'm back to +/- 1C variation now. This doesn't prove out that the crimp connections are the source of the issue, but the fact that I never saw the issue for ~2 yrs and ~300-500 hrs of printing, then it became intermittent (once every ~50 hrs), then last night it was every few minutes, makes me think that this crimp experienced some kind of quality degradation over time that progressively worsened. I'll only know if after another 50 hrs I don't see the problem, but I'll consider it fixed for now, and have ordered another thermistor just in case.

In the graph below, the +/- 1C variation here seems due to not having any filament present; the increased thermal mass and increased thermal drain from filament present, plus increased cooling from having a part below, probably accounts for the sub - +/- 0.2C variation I'm used to.

@dc42 - Definitely interested in your thoughts on this.

[Veti]

i would consider ordering a backup just in case.
have a look at the v6 upgrade
https://e3d-online.com/block-sock-v6-upgrade-kit

[brandonh]

@veti I have the new-style E3D with the sock, which uses a cartridge. There's a screw to hold the cartridge in, hence my confusion.

3 hrs of printing in, and no hint of the issue. That's a good sign.

[Veti]

for reference this is the old style that used a normal screw to hold in the thermistor.
https://e3d-online.com/thermistor-replacement-kit

a bad crimp job can deteriorate with movement over time.

[dc42]

@brandonh said in Heater faults, but rarely:

Update:

I tried jiggling the board-to-effector cable and the effector crimp cable for the thermistor, and I could not see any evidence of the problem seen last night. That makes me think that nothing from the effector up is relevant. I unplugged and replugged the thermistor plug (connecting the effector to the thermistor) too. Now the problem seems to have gone.

I'm back to +/- 1C variation now. This doesn't prove out that the crimp connections are the source of the issue, but the fact that I never saw the issue for ~2 yrs and ~300-500 hrs of printing, then it became intermittent (once every ~50 hrs), then last night it was every few minutes, makes me think that this crimp experienced some kind of quality degradation over time that progressively worsened. I'll only know if after another 50 hrs I don't see the problem, but I'll consider it fixed for now, and have ordered another thermistor just in case.

In the graph below, the +/- 1C variation here seems due to not having any filament present; the increased thermal mass and increased thermal drain from filament present, plus increased cooling from having a part below, probably accounts for the sub - +/- 0.2C variation I'm used to.

@dc42 - Definitely interested in your thoughts on this.

The regular oscillation of the hot end temperature can probably be eliminated by increasing the D parameter in the M307 command for that heater. Try increasing it by 30%.

[brandonh]

@dc42

Yep - did a re-calibration from actual room temp and the values are back to fully stable.

Also, I removed the housing from the effector thermistor, looking for any issues, and the crimp was clean. The wire is pretty small so maybe a good crimp wasn't after 2 years of shaking. I went ahead and soldered it just in case, and I haven't had any temperature errors in about 5 hrs now. It's not proof that I've fixed the issue, but it's a good sign! About the only thing left as a possible source would be the thermistor wiring atop the effector that connects to the Duet.