Hack,
My new favorite method for thin wall CR is TIG with silcon bronze rod. If I was doing any amount of daily welding of CR I'd use MIG...depending on fit up and accessibility. I had a tough time getting my torch into the crevices...should have been using a pencil type torch with the low amps I was using. Did you know Ducati frames are MIG'd CR tubing? But, these days, yeah I'd go with TIG brazing with Silicon Bronze, great for not so good fit up, minimal heating of the CR etc.
For the most part I don't even recommend CR for bike triangulated race bike frames. Unless a person is an engineer and can save those last few ounces by designing a frame using the rigidity of thin wall CR...then just use proper design and good DOM tubing.
Although I also have never seen the cracking susposedly a problem with welded CR frames. I tended to anneal the welds a bit with a gas torch afterwards anyway....not sure if it helped or hurt.
That first frame I built on the web site was kinda a piece of crap...but, it weighed like 7 pounds and held up nice for years.
I'm still not great at welding in tight spots around tubes that enter at steep angles....just not the right equipment in most cases.
90% of the welding I do is on mild steel, so as you might expect that's all I'm really good at. I'm one of those guys that like to TIG most of my mild steel work. I use the MIG for big stuff, stairs, railings etc. TIG for all the thin stuff, exhaust, swingarms, SS, tools, repairs etc.
I'm no expert welder, just the skill required to do what my jobs require. I'll never have the skills of a full time welder. But I do have some experience welding a bunch of different stuff. Problem is I don't do it enough to remember what I got to work the last time. Hence the masking tape notes stuck to some of my machines with the settings that worked on odd materials.
JohnnyB