Posted: 12/2/2022 9:27:38 PM EDT
I should probably just create a chronicle thread that covers my adventures.  So, I had my third failure on my beloved MK3S+ (well, my first one, now that I have two). Yes, I still love Prusa. First failure (at 4,500 hours mind you) was really quite glorious. It is still not 100% certain on what happened, but ultimately where I ended up is the thermistor wire sagged a bit too far, got yanked out by the bed sheet indexing pin on the back left of the bed, and in doing so, caused thermal runaway. And by thermal runaway I mean 40W heater running full tilt. It caused enough heat buildup that it melted the 3D printed E axis, which let the nozzle droop, which dug into the bed, which ripped the threads clean out of the heat block (which was probably EXTREMELY hot and soft at that point). When that happened, it ripped out the thermistor wire completely, finally causing a mintemp error and shutting the printer down. That thread is pretty concise but can be found here in the archives. Second failure was at 4,850 hours - 350 hours post rebuild, in which I took the opportunity to upgrade to a total ASA printed extruder/hotend housing and a Mosquito hotend (which are amazing, btw). Failure was simple in nature, with the front bearing seizing up on the X axis motor. I was able to quickly disassemble the motor and replace the bearing. That thread with a quick pic can be found here. Enter today. Third failure, just past 6,605 hours. Thermistor wire broke, in a very odd spot...just behind the heat block. Upon inspection, the "leg" on the E axis that holds the extruder assembly's wiring as it exits the extruder body is quite loose, so I'm guessing that induced left/right wobble that over time let the wire break. The thermistor wires are VERY frail. This is quite possibly the second time one has caused failure, and I feel like thicker wire should be used for such a critical piece. At any rate, I have an extra one on hand, so I should be back up and running tomorrow. For now, printer 2 is happily buzzing along, with 225 hours on the clock, so she is still new. Attached File Happy printing, friends! |
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Quoted: The latest firmware from a few days ago? The new fw monitors the energy used by the hotend. If it exceeds what it should, it trips a fault and kills the juice. Whatever firmware was out like, 4 or 5 days ago when I flashed them. I'd have to go look. It was mintemp, this time at least. Break in the wire. MK3 reads that as 0C, and triggers a mintemp error. |