Hey, you're just the chap I want to talk too.
Welding thin bike frame tubing? How easy was it with a Mig?
I'm going to build a recumbent from old bikes and do not have the
facilities to store oxy/act. I figured I might just be able to get
away with mapp/air, but It's going to be tricky. Fine for smaller
stuff, but doing a fillet braze might prove difficult. I'd been
steered away from a stick or mig welder, but you obivously had no
trouble blowing holes in the tube......but you're probably an
experienced welder anyway :-)
Enjoyed looking at that.
I was using 4130 tubing that came in a box of practice tubing from a
homebuilt airplane company. I had no problem welding that with my
110v mig. I also used 1" EMT, which I would occasionally blow
through, but it was easy enough to fill it in. My welds were strong
enough, but they were not pretty. At least they were shiny and
non-porous, with good penetration.
I like oxy/acetylene brazing to join EMT, but it takes a little longer
to light the torch, adjust it, and get the rod in place, then it does
to just pull the trigger on a mig. The brazing looks a lot better,
though. I have a little plumber-style oxy/acetylene pair of bottles,
and I think that would be plenty to do a bike. When I took my welding
class, one of the things I would do to prepare was fishmouth a whole
bunch of EMT, then take it in and braze and weld it together. If it's
fitted and jigged, it's really not that hard.
That was when I was thinking about building an airplane, before I
decided I had better things to do for the next three years. I don't
know what an FAA inspector would say about a mig-welded fuselage. I
don't think it would really cut your build time by much, though.