I may have chosen the wrong place to ask this question, but this seemed the closest match.
I am interested in adapting the 3D printer technology to building things out of low melting point metals. Before I put any money into this, I would like to understand just how a 3D print head functions. From my internet meanderings, I realize that a normal 3D printer melts a plastic fiber in the hot end part of the print head, and the feed process is due to the extruder. So when plastic is needed, i assume the extruder just steps the fiber slightly forward. I can't find any description of a "valve" or any similar device controlling flow at the end of the nozzle.
I'd appreciate very much if someone would either verify this, or set me straight.
Thanks in advance for any help.