Butt Welding ?

Thanks Bob, On a different note, does anyone have an opinion on what they feel the best gap is for butt welding 20 guage sheet metal using .023 wire? Im thinking .023. If using ..030 wire, .030 gap. The butt weld clamps I have are .040-050 so I am not using them. The look like they work awesoome, but Im thinking the gap is just too wide and will invite blow thru for my welding ability. I have access to the back of the weld in question so I can use a copper backing place the entire length of the weld and I have access to the back side for planishing as well.
 
Thats a question like filler over or under epoxy--except this forum--so it will depend on who you ask. I don't use a mig much and don't have an opinion, but I do know that I-CAR recommends a gap, but a lot of restorations guys say that is because its the safest way to be sure of getting good penetration, so a gap might be better for inexperienced welders.



There is an I-CAR​ article about this somewhere, but I couldn't find it, although I did find this utube from Australian I-CAR



​
 
Thanks Chevy.....I just found an new spin on filling a seam. In all my previous research, I had not yet came across this one. Wire bursh seam and remove all paint and seam sealer that is not between the sheet metal being joined. Spray a coat of weld thru primer. Use a piece of Tig filler rod the diameter to almost fill the seam. Use you Tig welder on a higher setting that required for the sheet metel being welded and stitch the Tig wire into the seam.


Any opinions on this?
 
chevman;n78395 said:
Thats a question like filler over or under epoxy--except this forum--so it will depend on who you ask. I don't use a mig much and don't have an opinion, but I do know that I-CAR recommends a gap, but a lot of restorations guys say that is because its the safest way to be sure of getting good penetration, so a gap might be better for inexperienced welders.



There is an I-CAR​ article about this somewhere, but I couldn't find it, although I did find this utube from Australian I-CAR



​
Click to expand...

ICAR recomends a gap for exactly as you stated. Inexperienced welders who are mig welding too cold, the gaps allows for penetration. You can achieve really good butt welds with a mig by taking more time, fitting the panels to weld like you would if you were tig welding; little to no gap. Bevel both panels 45 degrees and turn up the heat. makes for very nice welds with little distortion. (if you move around)
 
Thanks Chris. I did review the video Chevyman attached. I really like the idea of a slight bevel as well.
 
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