Fast desktop-scale extrusion 3D printing
Pushing filament with a gear was never a good design; it was just something that hobbyists could build easily. Injection molding machines use a screw drive to push molten plastic. This new machine uses a scaled-down version of the injector screw of an injection molding machine.Design and manufacture of injection molding screws is complicated but well understood.[1] They're not easy to machine, but that's what CNC mills and four-slide machines are for. It's like making a drill bit, something that's done industrially millions of times a day but is very tough for hobbyists.I'd wanted to use a laser for heating in a 3D printer, but not to heat the plastic being deposited. The fundamental problem with filament-type 3D printers is that you're welding a hot thing to a cold thing. That never works very well. That's what causes cold solder joints and weak welds in metal. In 3D printing, it's why the bonds between layers are much weaker than the plastic's inherent tensile strength. I wanted to have a small laser (about 10W) aimed ahead of where the filament is being deposited, to heat up the material already placed. That way, both sides are hot as the weld occurs, which should yield a much better weld.  This is what the heated build plate and heated build chamber designs are trying to accomplish, but they're not putting the heat the one place it's really needed.As lasers in the 10W range become more affordable, this looks like a better idea. A few years ago, it was an insanely expensive idea, but now, you can get 10W for about $300.[1] https://www.plasticsportalasia.net/wa/plasticsAP~zh_CN/funct...