Wow, that is a really cool build. I particularly like the adjustability. I'm definitely going to have to refer back for inspiration when I replace my Frankenstein used-to-be-a-treadmill-and-a-plant-stand off-road cart...

Awesome project, Jody. Just one question. Does the lower temperature used in tig brazing galvanized with the silicon bronze wire prevent (or significantly reduce) the formation of zinc oxide? If you had more than those two casters to deal with, would you have used a fume extractor and/or respirator?...