I got myself roped into a project making up frames for panels to protect stained glass windows when a church sanctuary is used for a gym during the school week. We went and got $800 worth of 6063 rectangular extrusion from the metal yard, and I'm having an incredibly tough time TIG welding this stuff. The main problem is the weld PUDDLES (TWO!) don't want to fuse, and I end up with the two pieces melting away from each other. (I did do a very respectable (for a newbie) weld on 2 pieces of 5052 1/16" without filler. I used a 1/16" Zr electrode, otherwise very similar setup, prep and technique.) I don't have a lot of material to spare while fooling around, either, we bought them out of an odd size, 1 x 1 7/8 x 1/8" wall. (That's 1 x 1.875" outside dimension.)
I just got in some 3/32 Zirconiated tungstens, a gas lens set for that size, and some 3/64" 5356 MIG wire for filler. I got a pretty good fit-up of the edges after a whole bunch of fooling around with my 4x6 hor-vert bandsaw. I tried to weld this with without grinding a vee to fill, maybe that is part of the problem, although my TIG book suggests that is possible up to 1/8". I have a Lincoln Square-Wave TIG 300 that as far as I know is working perfectly. I have a Weld-Craft water-cooled torch with a Miller cooler. I know that MIG wire is not the perfect thing for TIG, but I'm not even sure I need filler wire. (I also have some 4043 filler, and will try that next.) What Argon flowrate should I use with a #6 or #7 cup and gas lens? Welder settings are 150 A max, AC, continuous HF. What wave balance would be good for a Zirconiated tungsten?
Does anyone have any advice on what to do, common newbie pitfalls, etc? Obviously I can't support the back of the weld inside the tube. Is preheat needed? I have a Bernzomatic propane torch and an Oxy-Propylene set (essentially generic Oxy-MAPP) but have no idea how much pre-heat to use. I did try welding a couple pieces of tiny scrap, and that went a LITTLE better, I did actually get fusion along part of the seam. That sort of supports the idea it needs preheat. I KNOW I'm in way over my head, here.
Thanks in advance for any help you can offer!