[HH] 3D print in metal via robot arm mounted MIG torch

[Tom Metro]

This looks like a MIG welding torch mounted on the end of a robot arm:

https://www.youtube.com/watch?v=NFF0QQIQDXE&feature=youtube_gdata_player

I'm not sure why we haven't seen more devices like this.

It appears to form a rod shape from the weld bead. All the rods in the
video are perhaps 3/8" to 1/4" in diameter. It isn't obvious from the
video is how it produces that shape, but I'm assuming the robot arm is
either moving the torch in tiny circles, or it is pausing in each
position just long enough for the weld pool to expand out to that diameter.

It seems to put down materially really fast, but the video may be sped up.

Amazingly it seem to be able to "draw" these rods at 45 degree angles or
even horizontal without supports, follow graceful curves, and spanning
tens of inches without falling over.

I've only seen the video, and haven't tracked down any articles explain
how this works or why it was built. One unanswered question is whether
it is limited to this 1/4" resolution, or can it make finer details.

 -Tom