New to TIG, trying to weld aluminum with no success

[crmorse]

This is an old thread, but I sure hope the OP got someone else to build the ladder.

I did, sort of. I gave up on aluminum since an AC TIG is outside my budget (or needs) right now. Instead I welded up steel brackets and bolted them with stainless steel screws.

 

[Willie B]

I weld aluminum all the time with AC. Aluminum forms an oxide layer almost immediately. Oxide melts at about twice the temperature clean aluminum does & you can't make filler stick to it.
I have tried welding DC. You have to run Electrode Negative. It only works in thick stuff. Form a puddle you can't really see because of the "skin" then plunge the filler through the skin into the puddle. It will not be a pretty weld.

 

[alexpops]

Looks like the problem was solved. I would have used stainless instead of the Aluminum with a DC only TIG.

 

[5030]

Old thread but, you started out wrong. You never prep aluminum with a steel wire brush, always with a stainless steel wire brush and you ALWAYS wipe the aluminum with either acetone or laquer thinner prior to welding.