Heater faults, but rarely

[Veti]

by how much are your temperatures fluctuating? any significant change in the heating curve in the dwc graph?

[dc42]

@brandonh said in Heater faults, but rarely:

When this happens, what can I do to get some debug on this?

When the fault occurs, the GCode Console window and PanelDue console should have a message telling you what type of heating fault it is, for example "Temperature excursion exceeded 15C". If you have logging enabled (see M929) then it will also be written to the log file.

[brandonh]

Typical temperature variation is well below 1C. With a silicone sock and recent PID tuning, the values tend to range within 0.1-0.2C of target.

Thanks @dc42 - I'll add the logging for this. Is the temperature at the time of fault printed out to the log? If it's way off of the target, then I know it's a wiring issue, but if it's right below the target, then a heater or over-cooling issue would be more likely.

[brandonh]

@dc42 - I've set M929 but this doesn't show any more detail - just that it's out of range, not that it's above or below the setpoint.

After ~10 hrs of printing I hadn't seen the issue, and then I saw it a few times in a row, within minutes. I'm used to a rock-solid temperature, and now I'm seeing something very noisy:

!

When the extruder is not moving, the value is nicely consistent:

!

I re-calibrated the extruder heater but the values were pretty similar, and now, watching the PanelDue, I see the temp drop ~20C from the setpoint nearly instantaneously, then jump back up to setpoint. When heating from cool (as in the inline pic above), I don't see this (it would take many seconds to change 15 degress!), so I really have no idea how such fast changes are even possible.

The part I'm printing now is just a cylinder and it's seeing huge noise:

I'm wondering if I have a failing thermistor or heater connection somewhere... it just doesn't seem like the temp measurement is trustworthy. The fairly weak extruder fan I have now seems unlikely to cause such a temp drop.

As always, any help would be appreciated.

[Veti]

that does look like there is something wrong with the thermistor.
what hotend do you have?

[brandonh]

Some other issues I'm having, both related:

(1) Can't resume heating after a heater fault, unless restarting the whole board
After a heater fault, shouldn’t this clear the error: M562 P1 ? Regardless of this command, after a temp fault, any attempts to set a new temp value don't yield any change. Same thing with M562 by itself.

(2) Blob after resuming
This one I've also seen for awhile; after restarting then resuming after the print failure (M916), I typically see a large blob on the print. The extruder moves into near the starting position, seems to dump filament, and then restarts. In some cases, the blob is so large that the extruder catches on the next level and causes the print to fail.

I'm running the 2.03 Duet WiFi firmware now and have seen both today after the upgrade and since at least 2.02. Has anyone also come across these?

[brandonh]

@veti It's a genuine E3Dv6 on a Smart Effector.

[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.