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Entombing that mess with a squirt of hot melt glue
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I suspect the various power levels and current capacities have pretty much the same degree of integrity…
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That regulator runs surprisingly hot when fed from +12 V.
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you can even get 12 V 30 W heaters (the same dissipation as the existing resistors) with a 1000 °F (call it 500 °C) temperature rating.
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When a resistor fails, the heat goes off, the plastic stiffens up, the DC extruder motor stalls, and the essentially unlimited motor current kills the A3977 driver on the extruder board.
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Remember that the time constant doesn’t depend on the heater power.
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I’d say the MK5 thermocouple is spot on.
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What I’m trying to find here is the minimum power required to heat the head to 225 °C
The Smell of Molten Projects in the Morning 