Heater decoupling at the same spot on a print

[TMIB]

I've been trying to print this planter as a Christmas gift: http://www.thingiverse.com/thing:1236962

With my current settings, its showing up as about a 22 hour print. Every time I print it, I get to around the 10 hour mark and then the printer shuts down. The error shows that the printer thinks the heater has become decoupled.

Looking at the temp log in Octoprint, I see the hot end temp dropped to 0, then came back on, then dropped to 0 again. After sitting at 0, the "set" temperature turned off as a safety measure:

[img]http://i.imgur.com/38gi46V.jpg[/img]

I completely disassembled the hot end, verified continuity on the fuse, wiggled it a bunch to ensure it wasn't loose, checked resistance on the thermocouple, etc. It still dies about the same time. I tried re-slicing the model, in case something weird happened in the original slice, but it didn't make any difference.

What's weird to me is that if it was a loose connection, it shouldn't be dying at the same point on the print repeatedly. Other stuff I can print just fine, but you can see here, my 3 attempts at printing this all failed at about the same place:

[img]http://i.imgur.com/umwuolc.jpg[/img]

Any clue as to what me causing this failure?

[Jimustanguitar]

Are you using a Duet board, by chance? It's been a couple firmware versions ago, but I was seeing the exact same behavior with my thermocouple board on a Duet. I swapped out the thermocouple itself and later the amplifier for a different make and model that was similarly compatible, and the issue persisted. I'd like to think that it's been addressed by now, but I switched back to a thermistor and haven't had a problem since.

It may not be the permanent answer that you want, but it'll probably get you by before Christmas.

[TMIB]

Are you using a Duet board, by chance? It's been a couple firmware versions ago, but I was seeing the exact same behavior with my thermocouple board on a Duet. I swapped out the thermocouple itself and later the amplifier for a different make and model that was similarly compatible, and the issue persisted. I'd like to think that it's been addressed by now, but I switched back to a thermistor and haven't had a problem since.

It may not be the permanent answer that you want, but it'll probably get you by before Christmas.

Nope. I'm running the stock RAMBO board, and the stock HE280 hotend assembly.

[nebbian]

It has to be a loose connection somewhere between the Rambo and the thermocouple. I would go through the entire wiring between the Rambo and the thermocouple, examining and possibly redoing any joints in the way.

I'd imagine that it's to do with the cable umbilical flexing in a certain way at that height / position, which is opening the connection.

[Mac The Knife]

HE280? PartDaddy came up with this clip for the connector,,,, http://repables.com/r/808/

[geneb]

FYI, it's not a thermocouple, it's a thermistor.

g.

[TMIB]

Thanks Mac! That did this trick. I printed out the clip and tried again. This time at about the 10 hour mark, I noted that the bowden tube has a bit of slack in it at full extension, and due to the particular print angle, the tube and wire whip were getting caught against the arms for a moment on every pass. It would then "flop" the slack as it moved past the arm. This undoubtedly was working the plug just loose enough to lose contact momentarily.

With the clip, it worked fine, and my print completed!

Thanks!

[img]http://i.imgur.com/viCp5up.jpg[/img]

[geneb]

It even looks happy that it finished.

g.