Aluminum welding with a mig - with out an expensive spool gun

[smoothmat]

Hello,

Well today i have to weld some aluminum. My tig is DC and i dont have a spool gun for my Mig.

Here's what you do.

Get a spool of 5356 0.035" aluminum mig wire. ~$10
Remove the gun cable from your mig machine. (one plug and one retaining bolt)
Remove the steel liner. (unscrew first fitting on machine end of cable and pull)
Insert 1/8" teflon tbg to replace liner. ~$5.00 ( i used left over tbg from GP brake line)
Install gun cable to the machine.
Load and feed the alum wire - make sure to back off the feeder wheel tension. Alum wire kinks easy. To aid in feeding the wire; take off the tip.

Install tip and your ready to weld. Try and keep the line fairly straight.

I did this today and had great success. I have a 10ft gun cable and was able to feed the wire with a few 90 deg bends in the line. The shorter the cable the better. The teflon is used in lieu of the steel liner to prevent contamination to the aluminum wire. You may need to fabricate a brass collet for the machine end of the cable that goes around the teflon tbg. This is to make a seal so the gas doesn't escape out. After completing the change over; it should take you about 10 min to change over from steel to aluminum and vice versa.

You can swap you the liners back and forth for steel and alum.

I've attached a YouTube video (no, not me) showing how to replace the liner to give you an idea of how things should come apart.
How To Replace Your MIG Welding Liner

 

[Schmleff]

Interesting. I bought a bottle of Argon this summer but was not able to get the wire to feed through the gun without kinking.

What is the ID of the brake line you used?

 

[smoothmat]

I used a 1/8" ID line (http://www.ebay.com/itm/New-Ptfe-Teflon-Tubing-Tube-Pipe-hose-1m-6mm-4mm-OD-6mm-ID-4mm-/321241403468).
It was left over stock from my Great Plains hydraulic brakes. I am using a Hobart 187 handler. To properly setup for alum welding with spool gun and controller would cost about $500. I spent $10 on wire and $14 on box of 0.035 tips.

Welding alum is much different that steel. you can really notice when the heat of the metal by the flow of the puddle and sound of the the process. When you start cold you get a globular transfer mode and as the material heats up it turns to a spray transfer. You have to know when to stop your bead by the look of the puddle. There is no colour change like ferrous metals. It helps to pre-heat your pieces. This way your weld is much more consistent from start to finish. I just use a propane torch to pre-heat, brush (with Stainless steel brush). then lay a bead. Before i weld any piece i clean with acetone so that i don't brush the surface contamination into the material.