Framebuilders - Welding Question: Pitting

I'm finishing my first frame. The welds have gone well, except for the last one. The mother fing seatstay-steattube joint. I know I've put too much heat into the area trying to get the tungsten into cramped joint. When I finally was able to lay a bead it was bubbly and left pits. I've been told its from overheating or contamination. I've cleaned off the area with a wire brush and let it cool but I'm still getting the pitting. Its only like a half inch long area.

Is grinding the bubbled area down my best option? Anything else I should try? Thanks!

I'm by no means an expert, as I've just finished a tig class and have "only" fillet brased up till now. But my 2 cents to add to your theories would

be maybe a lack of gas coverage? Are you using a gas lens? They definitely let you stick your tungsten further out whilst maintaining coverage.

Check out Steve Potts site for this pushed to the max! He's welding titanium generally, which is much less forgiving of poor gas coverage.

Hope this helps.

I've been using a #6 lens for most of the frame but switched to a #4 to get closer into the joint. But some of the pitting is in an area where I was still using the #6.

And wow, thanks for the site. This is incredible! (http://4.bp.blogspot.com/-68e2o4jQtpc/T-PBxoiwUpI/AAAAAAAAAeo/mjVdVf__z2g/s1600/DSC04249.JPG)

His welds are just incredible aren't they! Check out firefly (http://fireflybicycles.com)cycles if you haven't as well.

Are you using a pedal? and/or pulse?

They didn't have pedals at the course I did and most students weren't interested in pulse either

I guess because they were aiming to weld thicker stuff.

oh also have you seen this (http://www.weldingtipsandtricks.com/)? It's not bike specific but good info.