question mig aluminum

You are right. You are using the wrong machine. I really hate the whole idea of aluminum in a 110 volt MIG.

A few people get it to work, but for everybody else it is frustrating.

The rules of Aluminum MIG in a push feeder.

1. Smooth drive rolls.
2. Just barely enough drive roll pressure to keep the wire feeding.
3. Keep the gun cable as straight as possble.
4. You must constantly clip the wire off flush with the tip, after pulling any slack out of the gun cable.

The idea is that if the wire sticks in the tip, it doesn't get a chance to birdnest. The smooth drive rolls and light feed pressure will combine to allow the wire to slip in the feeder if it jams.

As EL says, try not to do this work because it is REALLY HARD to get a good, consistent result. I did the fenders on this trailer

my SP125+. It was really, really tough to get a good, consistent long-running bead. What is happening at is your contact tip is heating up to the point where some small section is fusing to the aluminum feed wire. With the low power you have to run the wire gets really hot (due to the good conductivity of aluminum) and cannot cool the tip.

My technique is to run a solid bead for about 4", then stop the arc, flip off to the side and start the feed, letting about 8" run out. The combo of fresh gas and cold wire running through the tip will cool it off enough so you will not get fusion inside the tip. Same sort of motion as the 6011 flick, but with a pause and pull and cut. Also I run about as much argon as possible, just for the cooling.

The whole pause, cool, wait, jam, clean, re-feed cycle on these machines makes them unproductive to use. But if you are really in a pinch, they do work.

Longer stickout will help keep contact tip cool a little longer but you can have shielding gas problems. Exstended nozzle that resesses contact tip will help retain shielding gas and keep tip cool. Can also try counter booring last 1/4" end of contact tip over size.

frustrating.

Just for a data point, I have been using a Hobart Handler 180 (220V) with Aluminum for a while now and have never had a birdsnest jam. I'm using the original roller, very light squeeze, straight gun, clip-off wire end - BUT I also use a separate standard liner and tip that is .010 larger than that wire I'm running. This makes a huge difference! So, for .030 wire, I run an .045 liner & tip. The extra power helps a lot as well :-) I can do 1/4" no problem.

CG

"CG" wrote

BUT I also use a separate standard liner and tip

I used to intentionally do that on all my shop machines. It also increases their life by having more space to fill up before the crud starts to restrict the wire. I went through about ten liners before I discovered that. Then I got a .045 by mistake. I didn't have another, so used it, and noticed that it worked fine. After a long time, I noticed that it was working longer than any of the other proper sized liners did. Then I noticed it REALLY lasted a long time, and since then, I have always used oversized liners. I know it is not according to Hoyle, but it does work, and I don't believe it really causes any harm.

Steve