aluminum melting

[rogersh]

I am having trouble tiging 6061 alum. Trying to weld small(1/4" thick x 1" long x3/8" high) to 1 1/2" x 1 1/2" angle. by the time i get the angle up to temp the small piece has melted. I need to keep the bead as close to 1/8" as possible. Using miller syncrowave 350LX. 3/32 thoriated tung. have tried 1/16 and pure tung also. using #5 cone.

[Jeffw5555]

Aluminum and copper are tough because of their heat sinking tendencies. I've not had much experience with aluminum with different metal sizes, but have a ton of experience welding thin copper pieces to thick pieces, so I know what you are up against. You can't just start at the thin/thick joint. Start the arc on the larger/thicker piece away from the smaller piece until the larger piece just starts to puddle, then immediately move to the joint, with the torch angled somewhat towards the thicker piece of metal. It also helps to have the smaller piece clamped well to the thicker piece so it draws the heat from the thicker piece; not the arc.

[Fat Fab]

Add a heat sink to the thin stuff.

[B_C]

3/32 pure tungsten...any small cup.. argon, 130 amps and concentrate the heat on your thick piece and wash over onto the small part....Get the power on pretty quick before you malt the small piece run some rod as soon as you have a puddle....CAKE WALK Oh and set the wave to full pen...

[LarryL]

welding thick to thin aluminum

A couple of years ago a friend gave me some aluminum slugs cut off from a 3-1/2" diameter round bar. During an idle moment I decided to try fabricating a pen holder with one of the slugs, 3-1/2" diameter by 1-1/2" tall, and two pieces of 1" square tubing 3-1/2" tall with ~0.05" wall thickness. I don't recall exactly what output current I was using, but it must have been around 250 amp. AC. Being too lazy to preheat the large cylinder with a torch, I just continued applying the arc to it until the filler rod started to melt. The first beads I created didn't look too nice but the last few were decent. It is possible to weld very thick aluminum to very thin aluminum. You must direct the arc initially at the thick piece and then move it over to the thin piece when base metal begins to melt.

This pen holder certainly is not one of my works of art.
LarryL