Welding aluminum

[Major Ramifications]

Stupid question I'm sure, but here goes.
You can use a copper "spoon" to back up holes when welding steel and the weld will not stick to the copper. Is there anything you can use when welding holes in aluminum shut?

 

[zkling]

Copper, stainless or even polished steel will work just fine. Same as with steel, don't arc on the backing piece.

 

[Bondo]

Stupid question I'm sure, but here goes.
You can use a copper "spoon" to back up holes when welding steel and the weld will not stick to the copper. Is there anything you can use when welding holes in aluminum shut?

Ayuh,.... You can use copper, ssteel, or even steel to back it up,...

 

[dr_clyde]

I keep an assortment of copper bars for just such occasions. Works on steel, stainless and aluminum.

 

[RivennHewn]

Another stupid welding aluminum question.

How thin of material can you weld?

(coming from a wood guy)

 

[tomd]

My brother in law says he can weld two beer cans together.
He welds 8+ hours a day though

 

[koditten]

I do small outboard boat motor props. 4-5 a year generally.

 

[PugetDude]

My brother in law says he can weld two beer cans together.
He welds 8+ hours a day though

Lots of youtube videos of folks doing this, the cans are about .0080" thick at the bottom/sidewall transition, double that at the top seam. Ask him if he can cut two strips out of the sidewall and ****-weld them together.. they're only .00045" or so...then post the pics...

 

[zkling]

I do small outboard boat motor props. 4-5 a year generally.

Do you have a relevant point to your post? I do a good number of skegs on outdrives and lower units every season. Never had the balls to weld on a prop. Do you have pitch blocks for reforming? Worry about balance? Or just work on the smaller ones where that really isn't an issue?

 

[machine_punk]

Well, with oxy-acetylene, I've consistently welded 0.050" aluminum sheet. You can go thinner. I've seen it done, but I'm not that good yet.

Of course, if you don't need the strength of a weld, you can braze or solder it, depending on joint design (again, I'd use oxy-acetylene to do that, but that was how I was trained.

Kev

 

[koditten]

Do you have a relevant point to your post? I do a good number of skegs on outdrives and lower units every season. Never had the balls to weld on a prop. Do you have pitch blocks for reforming? Worry about balance? Or just work on the smaller ones where that really isn't an issue?

I was replying to the person who asked whats the thinnest aluminm that can be welded. 25hp and under is what I weld up. They are so small I just eyeball the blades. No one has complained about balance yet.

I just build up the traumaed area then grind and file to shape.

 

[Major Ramifications]

Thanks guys, I didn't know that copper would work with aluminum as it does with steel. I bought an old aluminum boat that the PO drilled some holes in and I'd rather MIG weld the holes shut than put bolts in them.

 

[NASTYZEN]

I use a piece of Copper that's 1/4 inch thick for plugging holes. Aluminum won't stick to it with ether Tig or Mig. It also acts as a heat sink and helps keeping warping to a minimum.
I've even used plugs of copper rod to do the opposite, built Alu. welding up around it then pulled them out leaving a hole.

 

[zkling]

Thanks guys, I didn't know that copper would work with aluminum as it does with steel. I bought an old aluminum boat that the PO drilled some holes in and I'd rather MIG weld the holes shut than put bolts in them.

Have fun, welding on old small aluminum boats can be lots of fun. If it is solid it's not to bad, but if you have any bit of corrosion in the surrounding area it can be daunting at times. The usual limitation on copper backing for the little guy is $. What I have used many a times is short section of large diameter copper pipe, flattened in the press to act as a thin plate. Sometimes slightly convex to act as a spoon. Unless you are really pouring the amps in that is usually more than enough to keep the weld from falling through.

 

[dr_clyde]

I've seen Ron Covell weld aluminum foil. I'd like to try it someday.

In high school we used to take turns welding pop cans together. That was with a syncrowave. A dynasty or aerowave will have better arc control and be more versatile.

 

[Professur]

I nearly bought an old Linde plasma welder about 10 years ago ... was told it could weld beer cans ... but I didn't have any way to get it home at the time. I kick myself regularly for letting that one slip past. Haven't seen another one since.

 

[rsanter]

If you are trying to weld the aluminum of a old boat....good luck

You better get the really clean or you will have nothing but problems.
Unless you really need to make an invisible repair I would cut a patch of aluminum that is about 1/4" bigger than the hole and place it on the backside backed with a copper plate.
Weld up the hole and leave the patch plate. That will be the strongest repair for the application.

If you just have to have an invisible repair. And the ogle is bigger than about 3/16"
I would cut a plug to go directly into the hole. Put the plug I. And a light hammer and dolly work to pien the two together. Back with copper and weld along the seam

If you try to ' weld up' too big of a hole like you may be able to get away with in steel with a mig. You can overheat the aluminum and it will become a bigger headache

Bob

 

[Southernbuild]

When welding an old thin aluminum boat, (with a stick welder, and a much too big electrode) it doesn't heat well at all. The three stages are: 1. Too cold. 2. Starting to look shiny. 3. The metal turns black.

Note: the aluminum doesn't really turn black, it just looks that way when your entire puddle overheats, and blows out. Then, you have a much bigger hole than you started with.

TIG, with backing is MUCH better