Welding Aluminum Jon boats

First I want to say hello to all and thanks for the site.

I am living on a military budget with limited money, I have purchased a $50.00 12FT jon boat. The previous owner had used 1/4" carriage bolts to attach 2X6 boards to the bottom for ribs. I have removed them and now I have about 25 1/4" holes in the bottom and when I started stripping the paint I found about twice as many 1/8" holes that was patched with some type of silicone. It had no seats and only one original rib in the very front, there are at least 5 cracks from 1 inch to 3 inces in the bottom. A friend of mine let me borrow a 110 volt Lincoln welder that uses wire spool and welds steel and aluminum. He is not really a welder and has only welded steel but never aluminum. My question is do I really need to purchase a tank and argon gas to weld the aluminum or can I just use the electric weld for the patches and braces that I want to install. Now I know you all are saying" sell the thing as scrap aluminum and get your $50.00 back and find another, like I said money is limited right now and I have a Mud motor kit and a 6.5HP motor on the way with $600.00 in credit for that. Any advice or suggestions would be greatly appretiated.

Thanks!

You need Argon to weld aluminium.

Thanks Crazy,

I will have to save up for that, I just want to try and finish my boat before the cool weather leaves the south, I like to hunt for hogs in the Alabama delta swamps.

If that Lincoln MIG welder has the gas solenoid to run CO2 or argon, you'll need a bottle of pure argon (not argon/co2 blend, that is used for steel) and a flowmeter/regulator. Set it to 15-20 CFH, unless you're out in the wind, then, you might need 25-30 CFH, and possibly a wind screen (sheet of plywood or tarp to block the wind) If the wind blows away your shielding gas, you will know it, because you'll have some black popcorn where there should be a weld, and you'll have a thousand holes in your shirt, and numerous burns on your arms, when the aluminum starts spattering.

Check the back of the machine to see if there's a brass fitting for a gas hose. If not, then it's a flux-core wire welder, and it won't work, at least, not without retro-fitting with the gas solenoid.

As for the wire, use .030" ER5356 wire, not 4043. 4000-series wire is NOT rated for marine use, 5000 series is. Not only that, but 4043 is much softer, it WILL jam your liner, drive rolls, etc.

You may even want to consider using a teflon liner in the MIG gun. Unlike the coiled wire liner used for steel, the teflon doesn't have all those internal edges that tend to shave aluminum as it passes through, causing jams.

When you weld aluminum with a regular MIG, it is VERY important to keep the gun lead as straight as possible. Any bends, kinks, etc, will cause bird-nesting of the soft aluminum wire. Trust me, I've been through all of this. You can weld aluminum with a regular MIG, but it's a PITA, because of the soft wire and its tendency to jam in the liner...which is why welders who have to do a lot of aluminum welding usually do it with a spoolgun, instead of pushing wire through 15 ft of liner, it's only pushing it 3 inches, which greatly reduces bird nesting.

Use a flap wheel to remove ALL traces of paint, silicone, etc from the area you want to weld. Then, you MUST use a stainless steel wire brush, to remove the aluminum oxide left over from grinding.

Unlike steel, which is forgiving of contamination, aluminum is NOT. You want it so clean you can eat off the surface.

Any contamination in your base metal will result in "popcorn gobble" that's what I call it, because it looks like burnt popcorn, instead of a weld, and has no penetration into the base metal.

I agree you should get a bottle of Argon.

But with that said, when I got my new Millermatic I got it all set up with Argon and a spoolgun and started practicing on aluminum. It wasn't too hard. One time I was practicing and forgot to turn on the gas .... the welds looked terrible and were black and sooty, but they were welds and would most likely hold.

My point is, you can always try it without the gas. Frankly, its a bad idea .... but what do you have to loose? If you blow a hole in your boat, it won't really make a difference.

Honestly, I think welding is the wrong route to head with this project. If you had the welding experience, and different equipment, it would be a different story, but trying to MIG weld aluminum with a 115v machine and no spool gun/push-pull gun is really an exercise in futility for accomplished welders with much experience.

If you've got a bunch of bolt holes, I'd suggest filling them with rivets. On the cracks, drill out the ends, then rivet on an aluminum patch, sealed with 3M 5200. Given the info in your first post, I really think this makes more sense for your project timeline/budget.

MrSimon said:

I agree you should get a bottle of Argon.

But with that said, when I got my new Millermatic I got it all set up with Argon and a spoolgun and started practicing on aluminum. It wasn't too hard. One time I was practicing and forgot to turn on the gas .... the welds looked terrible and were black and sooty, but they were welds and would most likely hold.

Click to expand...

They might 'hold' but at a greatly reduced percentage in strength when compared to a weld made with a proper shield of argon. And as an AWS certified welder who's welded on hundreds of boats over the last 18 years, I can PROMISE you, trying to weld aluminum as thin as a johnboat without shielding gas, you WILL blow holes in the aluminum. I don't recommend even attempting such.

PSG-1 said:

They might 'hold' but at a greatly reduced percentage in strength when compared to a weld made with a proper shield of argon....
...I don't recommend even attempting such.

Click to expand...

This is very true. That is if one even gets them to the point of 'holding.'

Exactly. I've actually tack-welded aluminum parts to a steel table, to hold them stationary. Welds 'looked pretty' but when flexed to break them loose from the table...you could clearly see the porosity, the metal looked like a sponge. Aluminum is a porous metal itself, with a melting point about 1/2 that of steel, so, it's very susceptible to contamination and porosity.

I don't see an ROI for equipment/ tools just for this boat. If the boat is just an excuse to buy the equip ok. I'm with Bassboy, welding is not the way to go. Rivets, patches and 5200. If you follow his posts you will see he is extremely knowledgable on fabrication with alum.

First I want to thank everyone for taking the time to try and help me out with information. After weghing the pros and cons and the fact that I am not an actual welder I have decided to bite the bullet, sell one of my guns and buy a boat that needs no work. I am greatful for a site like this to help out those of us who are just geting started in boat ownership. I am sure I will have more questions in the future and maybe some answers.
Thanks,
Gary

Good choice. Keep us posted on what you get.