This is from "Welding tips and tricks" on u tube. Good vid of the tig torch work.
Jody is not a frame builder but obviously an ace welder, he has vids of all types of welding.
You have to smile at his "quality control" at the vids end!
http://www.weldingtipsandtricks.com/...ding-bike.html
and here is the framebuilder's site that gave him the mitered tubeset:
According to Mike Zanconato of Zanconato Cutom cycles ( thanks for all the help Mike!!) "Compared to 4130, this alloy has about half the carbon and chromium content that 4130 does, but it has about 3 times more manganese and also vanadium added. This allows the wall thickness to be reduced to 0.016" in some cases. "
Brian