Tig question
 

What size tungsten and cup is everyone using to weld 18 to 20 guage steel? How is the proper cup size figured? Non gas lens.

TIG size
 

I use .o4" or 1/16" tungsten. More likely use the .o4" for tacking. I don't see much variation on gas cup unless I am outside, or by a draft inside. Typically a 3/8" opening. I use bigger pyrex ones(1/2") just because I don't have small ones. I always use a remote pedal.

Dan,
This might help:


https://www.millerwelds.com/resource...ing-calculator


Good luck
Pat

For sheet metal I was used the same sized tungsten as the metal thickness. So much easier and less burn through, better heat control and less distortion that way. Cup size I used small to save of gas and you only have a small weld pool to protect.

1/16 tungsten sharp to a point, #5 or #6 cup. About 12 scfm argon. Keep your arc length as short as you possibly can without dipping. If you don't dip occasionally you're probably too far away. And if you have pulse it helps a lot for 16 g and thinner. If you don't have pulse built into you machine I think you'd be able to mimic a low frequency pulse with your foot pedal. I've run as low as 2 hertz on the pulse setting, you could get into that range with some practice using the foot pedal.



And I know you didn't ask but fit up is everything. Best to have edge to edge contact, any gap in a butt weld will promote the edges pulling back instead of fusing. Backers will help if you have spots that just won't fit quite right. I've used aluminum and I've heard people use copper too I think.

I use 1/16 tungsten, sharp tip and #7 cup at around 18 cfh. 1/16 filler rod works well, but .030 mig wire makes an even smaller joint if you prefer.