So i had some 1" x 1/4 flat steel stock laying around cut 4 4" and tacked them into a tube shape. started welding the edges up. Right of the bat someing was wrong. I really didnt use much filler rod both edges were filling nicely into echother. but as i finished one side i went to the opisite side and weled that one up. But as i stoped and looked at both my welds i noticed there was cratering. I new to tig and did some serching but i cant figure out what causes this? is it becuase i wasnt useing rod?