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  1. #1
    Regular 3D Printer
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    Smelly smoke leaked out

    Guess you all know what happened, termistor popped out of its hole. Luckily i was sitting next to the printer so only some smoke, no fire.

    But i think maybe the lining is burnt and will have to be replaced. May i pleas get the link here so i don't have to read all the post

    Also thought of a quick and dirty way, is is perhaps so that our filament guide tubes are the same as the lining ?

  2. #2
    3D Printer Legend
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    Bad news! Have you been adjusting the hot/end extruder lately?

  3. #3
    Administrator bolsoncerrado's Avatar
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    Seems the thermistor missplacement is our cancer lately

  4. #4
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    What is the best paste to fix termistor in it's place, can't we find out yet?

  5. #5
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    I used my PC's thermal grease "Artic Silver" on the thermistor and heater and after a couple of days, it had harden into a whitish cement-like substance... I think I can't remove the thermistor and heater without damaging them... Probably need a solvent to do the reverse... but it works very well, and holds the thermistor nicely.

  6. #6
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    Exhaust putty would probably be best

  7. #7
    Regular 3D Printer
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    Not sure if Exhaust Putty has good thermal coefficient, it's designed to shield heat so it might not be too good for the thermistor readings. Some users I googled also used some CPU thermal compound on the thermistor bead and then sealing it in with the putty.
    Once it cures and harden, it's almost as good as expoxy.

    It's made of Sodium Silicate
    http://en.wikipedia.org/wiki/Sodium_silicate

    Problem I find is that if you use the putty and it hardens after heat curing, there might not be a way to ever remove the thermistor safely without destroying it. And if you can't remove the thermistor, you can't change or maintain the heater block easily.

    I just wish that the thermistor was a screwed in version instead of a delicate glass bead !

  8. #8
    Regular 3D Printer
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    I'm with lawong, we need a paste that secures thermistor and transfers heat. But It can also permits the thermistor to get out safely with a decent force.

  9. #9
    Regular 3D Printer
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    Yes i was working on the heater block
    Thought i had been really careful and also checked the cables but still missed it was out
    I have now disassembled the extruder again and found that at least the lining seems to be ok

    So back to the tedius job of cleaning everything. And this time i will try to find a way to hold the termistor safely in place before starting it up again.

    I have an idea about running a thin wire of some sort through the small hole at the top and lock it between the legs of the termistor. The hole on the top connects to the hole the termistor rests in (at least on my machine). Problem just to find a wire that is not electrically conductive and still can handle the heat, any ideas?

    Basic problem i have that it all falls back on is that my extruder is leaking melted filament on top of the nozzle and even on top of the heater block. Really need got get a tight seal between the nozzle and the tube (pipe?), any ideas on that?

  10. #10
    3D Printer Legend
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    Quote Originally Posted by sm0orb View Post
    ..........Basic problem i have that it all falls back on is that my extruder is leaking melted filament on top of the nozzle and even on top of the heater block. Really need got get a tight seal between the nozzle and the tube (pipe?), any ideas on that?
    From memory! The top of the threaded tube when fitted should sit just below the entrance hole in the top of the extruder block so adjust it inside of the heatsink until this happens. Then screw on the heater block (the difficult part is to finish with this facing forward). You need enough of the threaded tube sticking out of the bottom of heater block in order to screw the nozzle on tightly as this will prevent leaks. Then you have to tighten the heater block onto the nozzle holding the nozzle still with a spanner. If it doesn't line up then you may have to adjust the threaded rod again to change the finishing position.

    There is an easier way of doing this but it involves removing the heater & thermistor wires which is probably not easier so therefore not worth explaining.

    Below is a photo (courtesy of DAF) of what it should look like when done, the arrow is to point out that there must be a gap between the heatsink and the heater block or the heater will not get to temperature as the heat will run up inside of the extruder block and cause a mess of melted plastic.

    Needless to say this must all be done with the utmost care or you will break/dislodge your heater wiring/thermistor and be in a whole heap of different trouble.

    10828016_942163799129163_8782073800743256297_o.jpg

 

 

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