Tuesday, April 15, 2008


Simple Hot Metal Valve

This is my prototype design for a field's metal extrude head. It uses the same brass tube that we use for the polymer extruder, and the same nozzle. The tube has a smaller silicone tube inside it and a notch filed in it. A solenoid clamps the silicone at the notch. There's a brass cup at the top full of field's metal (melting point 50oC). All the brass parts are heated by wrapping them in nichrome wire set in JB Weld in our usual way.

And it works! Here's the vid:

RepRap metal deposition head from Adrian Bowyer on Vimeo.

The heater (with no insulation) only needed a 50/50 PWM duty cycle at 12v to keep the metal molten, giving an average current about 600 mA.

Roll on electric circuits. Roll on electric circuits in full 3D...

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What are you planning to use as low temp flux?
When Ed built circuits using this by hand, he used ordinary soldering flux. It seemed to work OK. But I think the trick is to make friction holders for all the components using the alloy, rather than soldering parts in using it. That's what he did - making a chip holder and battery holders, both of which worked perfectly.
In my mind, I see the far end of this development being the development of an arduino-like controller board for RepRap created by dropping the appropriate components into indicated blanks in a printed design. If this extruder head proves acceptable, does anyone want to try using it to print interface leads to an Arduino Lillypad?
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