Hello,
I tried welding some 1/16" AL to some 1/4" last night and coulding get a decent puddle on the 1/4 without burning up the 1/16th. What's the proper technique for this?

thanks!
allen

 

Keep most of the heat on the thicker piece. It's hard to maintain a nice puddle by holding the torch in a fixed position (in relation to the seam), so you'd have to move the torch up and down accordingly, but still keep most of the heat on the thicker piece. Add the filler rod along the seam only though.

 

Thanks,
So, should I move the heat back and forth across the seam or down the length of it? And, will the puddle actually be on the seam half on the thin and half on the thick piece or will the puddle be mostly on the thick piece?

allen

 

Imagine that the seam is a horizantal line, you should move the torch along a vertical line to keep the puddle on both pieces. The puddle should be on both pieces evenly. Having said that, you also need to maintain a constant horizantal speed, otherwise you get beads of different sizes and heights (won't be pretty).

Practice makes perfect!

 

pre heat the 1/4

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Motorhead_AZ &raquo;</TD></TR><TR><TD CLASS="quote">Imagine that the seam is a horizantal line, you should move the torch along a vertical line to keep the puddle on both pieces. The puddle should be on both pieces evenly. Having said that, you also need to maintain a constant horizantal speed, otherwise you get beads of different sizes and heights (won't be pretty).

Practice makes perfect! </TD></TR></TABLE>

Thanks, that clears it up!

allen

 

If you pre heat the thicker it will help too.

 

What size/amerage tig machine are you using?

 

Miller Syncrowave 180, not sure what amps to set it at to tell you the truth.

allen

 

I'd say go with 3/32" pure tungsten, and set the machine at about 150-160 amps. You may not be using all of it, but it's nice to have it in reserve. Aim the torch straight down onto the 1/4" aluminum until you get a shiney puddle started then slowly tip the torch up to move the puddle closer to the 1/16". Now would also be a good time to add some filler, while dipping at the 1/16" piece instead of the 1/4" to give it some extra thickness.

 

it depends on the joint you're doing - for a lap it should be pretty obvious . For a T, I'd use a tungsten and amps the same if you doing two of the small sections together - 1/16" red and 90-100 amps. My technique on T's is to let the arc ride on the vertical piece, tap the pedal to get a puddle and let gravity drop it onto the horizontal (or with finer control, you "push" the droplet of molten Al, with the arc, down to the base piece). That means you want the thicker section vertical. Having it horizontal means you need big amps to start a puddle, and the thinner vert. piece acts as a heat sink, sucking away heat and melting before you can get the puddle to bridge the seam

 

Excellent tips guys, thanks, can't wait to try this again!

Fred