[Jet City Fab]

Ive been building MOTORSPORTS roll cages for about 3 years now. When I first started building them at a race shop I used to work at, my boss had me MIG weld the joints. Now that I have my own fab business, I have been TIG welding all the joints. Looks better and I like not having all the spatter over the cage.
Most of the cages I build are DOM 1.5" .120 wall. I've been using a 3/32" electrode with 1/16" filler. I was just watching one of Jody's video's again and he used 1/16" rod to tack the joints and then 1/8 rod for the welding. Was wondering if there is any benefit to using the bigger rod for the joint welds other than not having to dip as often and/or dipping it as much. I guess I've just used the 1/16" rod just because I can keep a tighter arc and have a tighter bead.

Is this just a kind of "personal preference" kind of thing, or would I get better penetration with adding more material with the larger rod?
-Caleb

[Otto Nobedder]

The only distinction that comes to mind for me is a smaller heat-affected zone with the larger rod. The justification being, as soon as the puddle is hot enough to accept the 1/8" rod, that dip cools the puddle more than a similar dip from a 1/16" rod.

I think this is going to fall in the "personal preference" category until someone can show me some empirical evidence. Comparing the size of HAZ's for the different filler sizes would be a valid example.

I doubt you'll see a difference in penetration, if you're handling the rod effectively.

Steve S

[big gear head]

I use 1/16 filler too. It's easier for me to run a smaller bead with the smaller rod. I hadn't considered the HAZ.

[Jet City Fab]

That is a good point. I'll have to do a test on scrap pieces and see what the differences are. Thanks for the input Steve.