I need some help doing T-joints on thin aluminum (unsure of thickness, but it's only a hair thicker than my 1/16" tungsten). I've got 1/8" down easy and lap welds on the thin stuff are no prob, it's just the T-joint on thin stuff that's giving me trouble. I read the Miller articles, and now have a 1/16" red tungsten (doesn't ball up nearly as quick as the green) and grind to a point - the point really helps direct the arc, but melts away in minutes, so I can only direct heat at only one side at a time.

I can still do a decent weld, using 100A, by aiming the arc at the large fillet mass, feeding filler on the leading of the vertical piece, then a quick tap of the pedal to let the filler melt and drop down to the base - but it leads to an overly large bead, ~3/16" width or more. Now, a few times, I could aim the arc right at the join and add minimal filler and just fly down the seam, but it's really tough to do after the first 5 minutes or so.

So my question is, how can I control and aim the arc better? Also, the Miller stuff says to grind to a sharp point then add a land - what the hell does that look like? Is it like a radial v-notch, like the 2 piece tip of a BIC ballpoint pen, or what? So, I guess I'm just looking for some tips from the pros here - I'm in an open lab at the local CC with 4-5 classes left (the instructor, while a MIG and FC genius, is worse than me at Al tig), so you guys are my last hope

 

i also took a class this semster in welding... when welding ac, the tungsten will always ball up... its because of the reverse of electrical flow... dc welding stainless and such will allow for the tungsten to stay sharp... best advise i can give is work low amp... probably around 75amp and try to get as close to the joint your welding as possible... i learned t-welding with the thin aluminum and it was very frustrating at first till i was able to maintain i tight gap from the joint... also try different cup sizes(smaller) that can allow you to get in tighter(advise from my teacher)... last thing is play around with holding the touch to get best angle with still being comfortable... i am by no means an expert so......

 

Don't sharpen to a point, you're just going to lose it in the puddle and make a mess of things.

 

I have no problem getting in tight, in fact I have to be careful when adding filler that it doesn't melt and roll into the tungsten. My problem is getting the arc to go into the seam between the 2 pieces, instead arcing between the 2 pieces 3/16" away from the seam.

as far as not sharpening the tungsten, what shape should it be in?

 

I could swear 100amps is way too much for 1/16" (.065) alum. I usually set the max amps to thickness in thousands plus a little bit extra. That way I have plenty of room on the foot pedel above and below where I want my heat

 

When welding aluminum you have to go and not stop. You know when your at the right angle when you get the two pieces melting into one, and then start adding your filler. Go at a quick pace, and if you start to lose your composure, stop....start back into your bead and then keep going. Aluminum takes on heat bad! Its easy to over heat it, and undercut. Use lots of filler, and go like hell. Thats what worked for me, and i seem to be pretty consistent at it now. Great looking beads. I run around 85-90 amps.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chrisgvr4 &raquo;</TD></TR><TR><TD CLASS="quote">I could swear 100amps is way too much for 1/16" (.065) alum. I usually set the max amps to thickness in thousands plus a little bit extra. That way I have plenty of room on the foot pedel above and below where I want my heat</TD></TR></TABLE>

Well, aluminum is where I break this "rule". I set my amps depending on the size of the piece I'm working on. Aluminum sucks heat so quickly, that on larger peices it just pulls the lower amped heat too quickly away from my work area.

I've gone as high as 150 on .80 pieces, because they were huge, or were connected to even thicker pieces.

And no, obviously, I don't pre-heat.

 

I dial up 100A, but only really keep the pedal halfway down. That said, the bead puddle acts as a huge heat sink relative to the pieces and needs a lot more amps - my prob is getting the bead manageable at lower bead widths