Aluminum Welding Q's.... on my boat

[Permafrost]

I wasn't sure where to post this, but off-topic seems about right?

I'm in the need of some input, tips and tricks on aluminum welding from you welding gurus...

I'm modifying an aluminum boat hull. Building up the transom and adding some bracing. I have plenty of experience MIG welding steel, but aluminum is a different animal.
I have a Miller Regency 250 powering a Miller spool gun, aluminum filler wire and argon shielding gas.

I know to push the weld with aluminum rather than pulling with steel, and really have to move, but my welds are not very pretty
I can lay down a pretty decent bead after I get rolling, just starting and stopping is challenging.

Any tips for a novice? Besides going TIG...

[fastwillie 696969]

hire someone else

[mongoose]

Originally Posted by fastwillie 696969

hire someone else

+1...


a boat is probably the last project a novice needs... even if you can weld alum... a boat is prob one of the hardest things to fab.

[68C15]

forget the whole thing and buy my fiberglass boat. problem solved for both of us.

[Permafrost]

Wow, Helpful group.

I think I'll just check myself into a metal hospital now for even attempting any DIY projects.

Thanks for the great replies!

[BB72CHEVKT]

Originally Posted by Permafrost

Wow, Helpful group.

I think I'll just check myself into a metal hospital now for even attempting any DIY projects.

Thanks for the great replies!

Sorry for the wise crack responses. This is very unusual on this board. Please do not let it discourage you as I see your post count is only 23. Wish I could help. Good luck!

[PanelDeland]

My best advice is to get something else to weld on.Seriously,welding aluminum is like welding anything else,it takes practice to become proficient.Then you can try the boat.You'll need something in about the same guage.You could also try Miller Welding.They have a great website with lots of info.Some really cool projects over there too.

[LEEVON]

Man I'm sorry I don't know how to weld aluminum but I don't see why everybody is telling you to pay for it to be done. These guys sound like my Dad, if I listened to him I'd never have learned how to cut, weld, fabricate, paint or anything. He is a "you can't do it if you don't know how" guy. I say nonsense. You have the spool gun, filler and something that needs welding I say get 'er done. It's just a boat, not the space shuttle.

I needed an aluminum oil pan welded this week and took it to a boat fabricator, they were nice folks, bet they would be more than happy to show me how to do it but if I had the equipment I'd learn to do it myself. My motto is "A man can do anything with the right tools".

You might find some info here:

http://www.millerwelds.com/resources...rticles10.html

www.weldtalk.com

Hope this helps!

[Bus Ted Knuckle]

I agree that you should get some scrap and practice with it. You just need to play around with it. Aluminum has to be extremely clean to weld, I mean CLEAN! Dirty aluminum will cause some nasty looking welds, you might just need to prep the work better. And did I say you need to clean it good before welding it?

[fine69]

Sorry about all the smartalec responses. Sometimes humor is NOT the way to go.

If your welds look good during. But not so much starting and stopping just keep practicing.

I have the same issues with mig welding. But feel better after looking at the welds on semi-trailers and such.

Try,try again.

[GRX]

I'm a machinist not a welder, but knowing how to weld is an essential part of that trade. Or at least it used to be. Well anyway, maybe I can give you a few pointers.

Did someone mention the Aluminum must be clean? Yes. Think they did! Use a type of Acetone for this. Brake cleaners & the like can give off bad fumes. As well as leave residues. Also, get yourself a stainless brush & use it ONLY for Aluminum.

Pre-heating the Aluminum before welding can be a huge help. Make sure you have a clean oxidizing flame for this.

One important thing to be aware of is that Aluminum has a more narrow melting range than Iron/Steel. In other words, not much a temperature difference between the liquid and gaseous (burning) states. Therefore one cannot as easily rely on watching how the work piece & puddle glow.

Welding Aluminum definitely takes a bit more finesse than Steel. Hats of to the man (or woman) who can lay a perfect row of dime shaped beads with their MIG.

Hope that helps.

[CE20934]

Originally Posted by GRX

Did someone mention the Aluminum must be clean? Yes. Think they did! Use a type of Acetone for this. Brake cleaners & the like can give off bad fumes. As well as leave residues. Also, get yourself a stainless brush & use it ONLY for Aluminum.

One of those fumes is phosgene (nerve gas) which is why I never use brake cleaner on any part I'm about to weld. An aluminum-only stainless brush is one of the better things to have.

I can TIG aluminum with nary a problem. As has been stated before, practice, keep the work CLEAN, and preheat if possible.

[nds1968]

In my experience with a spool gun you will have a cold start and you need to learn when to stop welding before it gets to hot. When you stop hold the spool gun there with the trigger half pulled so that only sheild gas comes out. This will allow the weld to cool while being protected by the shielding gas which will help prevent porosity. Also if your getting a crater at the end of the weld let it cool for a second and weld it again to fill in the crater (this is where your weld will want to crack).

Also to help prevent the crater put a tack weld down and weld towards and stop when to run into the tack weld.

The stainless wire brush is a must and as mentioned use it for welding aluminum only.

Preheating is also and option but I only do this if welding 3/16 or thicker (you would be surprised at the amount of condensation/water that is drawn out of the metal).

Pics may help.

[68C15]

^^^^^^^^
very helpful information. I will have to lock this in the memory banks in case I ever get an aluminum boat.

[fastwillie 696969]

brake cleaner is very flammable

[cdowns]

boats need flex in some areas so depending on your extant of modifications a better way might be riviting to avoid stress failures in the future

[Hottrucks]

well this is up my ally and these guys have covered most of the importtant stuff..but heres a trick I learned from years of rebuilding boats and the lower gear boxs, and props

A piece of copper flashing under your weld helps in the burn though, it disapates some of the heat while holding the multon aluminum up in place but it won't stick to it...also they have a wax that you put on after your done to stop your grinding flap from cloggin up

Now to address your transom issue your probably trying to add about 5" to the height to go from a short shaft motor to long...???...there are some simple ways to do this without welding ( truth is the welds are going to break because of the stress/vibartion trust me). probably the best and easyest way is to add a peice of 2x6 and cut it as a filler the same thickness/shape as the transom...have a piece of aluminum cut and bent to go up the transom and over the 2x6 and back down the inside...use 3M 3200 and stainless bolts use the 2 exsiting bottom holes and though bolt it there using a plate inside as a backer....now when you mount the motor the 2 new bottom bolts will go though also the top clap will hold the top...add 2 transom brackets from near the top to the stringer and call it done...keep in mind the motor pushs on the bottom of the bracket not the top..if you have any more questions or I can help just let me know

[Number98]

The cleanliness is a must, always use the stainless steel brush...

Also the helix, keep in mind the spool size of the wire.... the spool guns use smaller spools of course and thus cause the wire to come out of the tip curved somewhat, you can give yourself some more gap from the work to see/watch the direction of the wire better and this will help the looks and penetration of your weld.

New tips help this, worn tips can add to this problem causing your wire to "jump" around some.

Keep in mind that MIG aluminum never looks quite as nice as a TIG procedure...

[LEEVON]

Here's another reason to DIY! I just picked up an LS1 oil pan from a marine shop that welded up a broken corner for me...for a cool $245!!! ($75/hr shop rate x 3 hours plus tax) and he didn't even machine the mating surface. Ouch! I could have bought a new one for that. They forgot to call me with an estimate so asked them to ease the pain a bit, paid $150 cash but man what a gold mine!

[Hottrucks]

^^^^ thats the toughest stuff to weld the oil penitrates the aluminum.....ussually a part like that has to be cooked for some time to burn off the oil and it still leaves some behind.....

[Permafrost]

Great! Thanks for the positive replys and advise!

nds1968- Exactly, the cold start at the beginning and overheat at the end was my difficulties.

Hottrucks- damn, I didn't think of the copper! I've been using copper backers when welding thin auto-body panels for years.

Number 98 and others- I use a stainless brush and have been trying to keep things clean. Also, great tip on the wire, I'll heed that advise.

I burned up a bunch of wire practicing and with your tips have had favorable results. I invited an acquaintenance with some experience over to the shop and he gave me an ok on my welds. I guess I was expecting steel-MIG results or TIG looks and that's just not as probable with my set-up on alum.

Now here is a couple of "explainer" pics.

This project entails a tunnel in the hull and the purpose of the added transom height is to align the outboard jet foot at the top of the tunnel. I run shallow water and props are a no-go.



There will be two additional 2"x2" box-tube braces that run from the transom to gussets added to the floor ribs. Plus all will get re-bolted at the factory locations. The inner part (under the cap) is sandwiched marine plywood glued and screwed.



Thanks again.

[irishman999]

That boat looks awesome! if your welding fails is that thing going to sink?

[Permafrost]

Originally Posted by irishman999

That boat looks awesome! if your welding fails is that thing going to sink?

LOL... I hope not. A crack might appear, but that won't be a terminal failure.

Transom is finished, now onto installing floor ribs and composite flooring.






.

[nds1968]

You look a little hot on the last weld in the last pic. You may also be moving to fast. Furthermore are you weaving or does the wire come out weaving? If the wire comes out weaving you can try to minimize that by loosining or tightening the tession screw on the drive rollers.

Also how much stick out are you running? I would run about 3/8" - 1/2" stick out on my spool gun. On a lap joint as pictured I would not weave. I would hold the gun around a 45 degree angle (alittle more or less depending on the thickness of that crossmember) and tilt the gun 10 degrees back.

I hope I explained it ok

Also can you get bolts in them crossmembers? If not I would pop a few 1/4" rivets to help secure them plates.

[Permafrost]

Originally Posted by nds1968

You look a little hot on the last weld in the last pic. You may also be moving to fast. Furthermore are you weaving or does the wire come out weaving? If the wire comes out weaving you can try to minimize that by loosining or tightening the tession screw on the drive rollers.

Also how much stick out are you running? I would run about 3/8" - 1/2" stick out on my spool gun. On a lap joint as pictured I would not weave. I would hold the gun around a 45 degree angle (alittle more or less depending on the thickness of that crossmember) and tilt the gun 10 degrees back.

I hope I explained it ok

Also can you get bolts in them crossmembers? If not I would pop a few 1/4" rivets to help secure them plates.

Ahhh, Yes the wire is coming out of the gun weaving. I will try adjusting the tension.

I've been seeing my best with about a 1/2" sticking out, my most difficulty was the keeping a consistant tilt-back.

The X members are channel and cannot access the underside. I may just rivet those as suggested. I have a nice H/D hydraulic riveter I've never used, here's a good opportunity!

Thanks for the tips and ideas.