Even "MOST RELIABLE" printer can fail, & AT THE WORST TIME:(

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Swami
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Even "MOST RELIABLE" printer can fail, & AT THE WORST TIME:(

Post by Swami » Sun Jan 28, 2018 9:45 pm

Well, it happened:(...

...In front of ~30 excited kids, parents, and others at a big event... "HEATER FAILED. HIT RESET". "Hm? Sorry folks, an error."... Toothpick to RESET button... again, "HEATER FAILED. HIT RESET". Resliced w/o heated bed... PRINTING!... then I hear, "It's moving."... Yup, came loose from bed. PLA, mind you, albeit I had yet to print such w/o heated bed. As most know, heat is not strictly required for PLA - and in fact, bed had hair spray prep on it. FYI, nozzle was NOT too high (I checked). "PLAN B": switched to another printer (DeltaMaker)... worked flawlessly:) - but I had already lost the original crowd, though luckily, others filtered into the exhibit room, so the show went on. Also, I was able to demonstrate some aspects of the generally awesome Makergear M2, including control via Ponterface, and the ViKi LCD controller, plus highlighted the Cartesian vs. delta designs.

So, with that out of my system, HERE ARE MY TECHNICAL QUESTIONS:
- What are common reasons for "HEATER FAILED"?
- And more importantly, what are the fixes?
- Might I have contributed to the problem? (Perhaps improper transport to the event? Or other?)

FYI, I checked the connections and they seemed fine. In fact, the connectors were so secure I couldn't even pull them apart! (At least not w/ what would have been great force.)

OK, TIA.

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ednisley
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Re: Even "MOST RELIABLE" printer can fail, & AT THE WORST TI

Post by ednisley » Sun Jan 28, 2018 10:54 pm

Swami wrote:What are common reasons for "HEATER FAILED"?
A failing thermistor (or cable), which causes the measured "temperature" to drop or remain constant with the heater turned on. The firmware notices this problem and shuts off the heater, because it cannot control the temperature.

This generally happens to the extruder thermistor, because it has fragile wires flopping around in free space and experiences a much larger temperature variation. It's not clear which thermistor prompted the message. I suspect re-slicing without the platform heater had nothing to do with the problem; thermistor failures often start as intermittent problems, so it may have been luck of the draw.

The connectors rarely fail. Most thermistor failures happen either inside the thermistor itself or at the point where the hair-fine wires leave the body, with occasional failures due to fatigue-worn wiring inside the braided loom at high-flex locations.
what are the fixes?
Based on past history, I'd order two extruder thermistors, install one, and keep the other on the shelf.

Stipulated: there may be something else wrong, but there's no way to tell from the evidence so far.
Might I have contributed to the problem?
Perhaps, if you bashed the extruder or platform wires while moving the printer.

From reading the forums, it seems to me folks who spend a lot of time disassembling / reassembling / cleaning / tweaking / changing filaments / nozzles / whatever have far more than the average number of thermistor failures, at least compared to everybody else. Might be confirmation bias on my part, but, for sure, the less you annoy the extruder thermistor, the longer it lasts.

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Swami
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Re: Even "MOST RELIABLE" printer can fail, & AT THE WORST TI

Post by Swami » Sun Jan 28, 2018 11:49 pm

Thx for the great reply, Ed. Yes, I suspected the thermistor. And yes, I have been deep into the firmware (got system to work in Marline 1.1.8/Arduino 1.8.5 - w/o issues, BTW), so have encountered the failsafe features related to thermistors. FYI, the error occurred on bed heating. Then resliced w/o bed heat; print started as usual (but failed to adhere, in the end - separate problem, though). So, this would indicated the bed thermistor, not the extruder (of course, the extruder thermistor could be intermittently failing - or less likely both). Also, performed bed heating from LCD controller; got same failure.

Will do some testing/troubleshooting when I get back to the machine. Sounds like a good idea to prolly good to have some spare thermistors lying around, so will get some regardless.

Thx, again. I really appreciate the supportive 3D printing community. And you are a part of it!:)

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Swami
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Re: Even "MOST RELIABLE" printer can fail, & AT THE WORST TI

Post by Swami » Sun Feb 04, 2018 10:53 pm

UPDATE:
- I fixed it!... by doing nothing:)
- Just reconnected everything back at the lab, and violá, works "as advertised".
(Not too reassuring, though. Gonna purchase some spare thermistors, "just in case".)

For now there's nothing (identified) to fix. So, gonna just keep printing!:)...

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