Tig welding aluminum

So i got my new PM 256 working and i figured i would start practiceing welding aluminum. Had some scrap 1/4 and some scrap 3/8 maybe a little thinner. started on the 1/4 just laying rows of dimes with out rod, turning our really good got my timeing down, used the step and pause, pulsing with the macine and also with the foot pedal. I noticed if i let weld cool down super fast while on the 1/4 it would crack so the foot pedal was working the best with step and pause 2nd best. All is good till i start trying to add rod. The best way to describe what the rod was doing was think of sucking something out of like a plastic wraper. It seemed like the aluminum was melting out of its skin which then the skin would contaminate the weld. What am i doing wrong?

My rod is 4043 3/32. Could rod size be causeing this problem or maybe bad rod. Im not sure of what the scrap aluminum is could it be the wrong time of aluminum to be attemting to weld?

Thanks for the help in advance.

Well i think i actauly fixed my problem here, i was useing the recomeded balance based on a miller come to find out after reading another post here on the forums these machines are actualy oppiste of the miller so before i left for work i went to 35 and low and behold i could run a bead and and filler to it.

Tallguy,

Down load the manual on our site and it will explain all of that to you. Miller is different than us with their polarity setting...Many of our other competitors are similar to ours however.

The idea is that positive + is cleaning...People often refer to it as percent of cleaning or ask "how much cleaning are you giving it?" So to stay consistent in thought and logic, we use a percent of + to designate this function. Miller give a percent of negative - as their scale. Its their choice and they aren't right or wrong, neither are we. Its a matter of semantics, but it can be confusing to be sure.

Tell me about it but ye i got home tonight after work and layed a couple bead and they were just about what i expected to see. Decent stack need to work on timeing and spaceing but over all a lot better then the 75% cleaning i was trying to use =P

what works good i use is a 3m sctch pad i clean my sticks with it before welding since the oxidixe

Yes a scotch guard pad works well. Follow up with acetone wipe down.

I find what works good to clean rod to is just straight white vinager