After putting in my 2nd thermistor I got some great test prints for various filaments, ABS, PLA, WOOD, Bridge... The first thermistor died after a couple of hours of printing. The second one gave me 20+ hours of printing before it slowly started to give false values.
It started when a nozzle jammed from too much heat raising up in the hotend, and the filament got wedged in the PETF tube. I cleared that and let the printer cool down. Or so I thought. I step away for just a few minutes, came back, and the temp read 27C. It previously read in the 200C-220C range. It didn't click that it cooled off way to fast. But I don't have a great sense of time to begin with. So needless to say I have 2 small burns on 2 fingers. As the printer continued to cool off it dropped down to -19C. Which was pretty impressive, and a clear sign of a problem.
I noticed extra blackness around the nozzle, so I took the hotend (now cold) out of the printer and realized the power resistors are now very loose. I went further and took them out, and cleaned up the RTV. Both resistors have melted spots, and crackes in the cases. And the hotend feed tube insulator bent a a little!
I think the thermistor went bad which caused the board to keep applying power to the resistors, which over heated the hotend, which melted the feed tube insulator a little...
I might be down a bit, but the bird feeder was coming out great!
-Max
Thermistor died, over heated hotend
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foshon
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Re: Thermistor died, over heated hotend
Those resistors cracking is normal. The rest is an issue.
Purple = sarcasm
Please do a board search before posting your question, many have been answered with very time consuming detail already.
Please do a board search before posting your question, many have been answered with very time consuming detail already.
Re: Thermistor died, over heated hotend
...and the resistors should be replaced!
g.
g.
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Defeat the Cartesian Agenda!
http://www.f15sim.com - 80-0007, The only one of its kind.
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Defeat the Cartesian Agenda!
http://www.f15sim.com - 80-0007, The only one of its kind.
http://geneb.simpits.org - Technical and Simulator Projects
Re: Thermistor died, over heated hotend
Got the new hotend, resistors, thermistors, etc, assembled and printing. After a Z calibration, it's off and running just as smooth as before.
I found the original problem. I had the fan wires switched, so the hotend/filament cooling fan was not coming on, except when the model needed cooling. <Smack forehead>
I took time to glue the spool holder arms to each other, and touch them up on a sander to give them a nice curve. Then added clear smooth packing tape around where the spool rides. It just glides off, no clunking.
-Max
I found the original problem. I had the fan wires switched, so the hotend/filament cooling fan was not coming on, except when the model needed cooling. <Smack forehead>
I took time to glue the spool holder arms to each other, and touch them up on a sander to give them a nice curve. Then added clear smooth packing tape around where the spool rides. It just glides off, no clunking.
-Max