I need some help.


I am making a gigantic " weather vane type thing" (technical term?).

(some very thick material and I am slightly intimidated)

its made up of 4 arms coming out radially from a central bearing unit.

the arms are a mix of rectangular tubing (6" x 2" x 1/8" thick.) and
3/8" plate.

the central unit is machined from a round of 12" 6061. it rotates on a
hardened point with a delrin collar.

I need to stick the arms to the bearing. The two pieces mate on a
flat groove vertically along the bearing.

____the question______

is the extra penetration gained from using Ar/He worth the extra
dollars?, (we've been using straight Ar)

also, aside from oxy acetylene, what pre-heat methods have any of you
had luck with?

any help would be much appreciated.