Glen-L.com

I'm not building an aluminum boat, but I am a professional aluminum welder if anyone has questions on the subject. I currantly use TIG and MIG welding processes to weld it. I am starting to use a new MIG machine with pulse technology. This thing is awesome, Lincoln Power MIG 300. It was designed for welding aluminum. It can make TIG quality welds with a MIG welder. The sweet thing is you can have the speed of the MIG, and porosity free wleds of a TIG, best of both worlds.

The thought of trying to weld aluminium gives me the shakes!!
Being a total amateur at this, I have tried joining some aluminium angle pieces together using an oxy-acetylene torch and some aluminium rod....and the whole thing strangely just suddenly melted and dripped onto my boots when I applied heat, and never showed any sign of wanting to fuse together...but I must have been doing something totally wrong...

Gas(oxy-acetalene) welding aluminum is very tricky. As you found out aluminum gives you no sign that is about to blow through. Check out this website, www.tinmantech.com Kent White sells videos and equipment for welding and forming sheet aluminum. I bought the complete set of his tapes on forming and welding aluminum a few years ago. I have been welding aluminum for about 3 years now.

Aluminum must be VERY clean prior to welding. Wirebrush it with a STAINLESS wire brush. You can wipe it with denatured alcohol before wire brushing. Aluminum starts to oxidize just seconds after it's wire brushed, so wait until you are ready to weld, or it will get contaminaited again.

Keep practicing. I have gas welded aluminum with some degree of success, but I won't be building anything that way unless I need to form that peice after it's welded. That's when it is most useful, the weld is softer than an electric welded one.

I saw an informercial on "Alumaloy" - sort of a solder for aluminum. They demonstrated the use of the stuff, using a brush and a plain propane torch. You have to heat the workpiece to 728 degrees, then apply the rod of Alumaloy. I was surprised at how well it flows onto the workpiece, and how easily it works. The stuff is not solder - it's some alloy (proprietary I'm sure) with a strength of 36000 psi, way higher than solder but not as strong as aluminum. My guess is it has something in it than is either able to adhere to the oxide coating or somehow dissolves it. One major dissadvantage: it does not like salt water - I guess it starts electrolysis. You'd have to keep it well protected or use for fresh water only.

Now, the hard part is buying it! It's $45 per pound, but they "give" you an extra 1/2 lb. Kinda steep.

I bought the kit, but haven't had a chance to try it yet. I wonder if boats could be built using lap joints? See www.alumaloy.net.

I saw the same infomercial. They make it look so easy and so effective. But then, all the infomercials do that! I'd be very interested in hearing the results of a real world use of the product. So, since you bought the kit, please be sure to report back with results after you've tried it some.

Thanks!

I've used a product called Techno-weld <http://www.techno-weld.co.uk/>
very successfully. I wouldn't want to build a whole boat using the stuff (!) but I've repaired aluminium and zinc castings, joined sheet aluminium, mended splits in aluminium car bodywork, all without problems and just with the use of an ordinary butane/propane torch.

I've seen that stuff(infomercial) before. They have a rep at most big car shows like Carlisle. Also, I have seen them at our state fair. I bought some about 5 years ago and never got it to work on anything that was worth a damn. Sure the guy on the infomercail can weld aluminum cans together, but thats about it. I took a part with me to the fair for the guy to weld, he tried but just succeeded to screw my part up. I'm not impressed, I'll stick to more conventional methods thanks.

I checked on Techno-Weld - they have a US distributor in South Carolina, www.techno-weld.com. Two major differences: They supply a stainless steel brush, and you have to scratch the workpiece THROUGH the molten solder to get a bond, and the tensile strength is higher at 50ksi vice 36. Also, they don't take credit cards OR personal checks, you have to send a money order! What a pain! I tried to compare prices, but they don't sell by the pound. If I get energetic, I'll calculate the weight of their kits and figure out who's cheaper.

But first, I need to find time to try out the Alumaloy and see if it really bonds without scratching through the molten solder. A friend of mine has a tig welder and was courious about Alumaloy- I gave him a piece to try out but haven't heard from hm yet.

DavidMcA,

Doing something Totally wrong?

I'm less than a novice welder but I did take a little metalurgy during my apprenticeship (many moons!). This info may not be current but it's a start.

Aluminium is one of the most unstable elements on the planet and has some very strange characteristics - particularly (but not pertenent) when you pass an electric current thru' (or near) it.

The only reason Aluminium exists as metal is that Aluminium oxide is exeedingly impervious. It's also exceedingly strong (used in abrasives, yes). You see Aluminium oxidises immediately on contact with air! (O2). Because it is so impervious oxygen cannot reach the Aluminium. The oxide skin is very, very thin so you don't even notice it!

Problem - Aluminium oxide opens up when heated!

Someone got the idea that if you could make the oxide open up and apply more oxygen then you could maybe increase the thickness of the oxide coating - making it scratch proof!!! .... long story..... can't use O2 - try some other gas high in O2..... hey, that works!!! BUT IT'S PINK! Different gas... BLUE! Hence ANODIZED ALUMINIUM.

Bit of a digression, hope you enjoyed.

If you take a flame to Aly it will try to dissappear on you!!! If you add an extra pile of oxygen... GUESS WHAT HAPPENS!

So you need to shield the heated Aly from any oxygen source... hey, how about Argon gas? It's inert, cheap and doesn't affect anything else? Hence ARGON WELDING.

Sorry if I sound like a teacher but I'm trying to write this quickly. Hope it's usefull. Sure someone can update it. I just didn't think the other posts were getting to the root of your problem, If you understand better what is happening I hope you will no longer "get the shakes!!" about welding Ally.

Ken
Calgary, Alberta
CANADA

Yo RCS&M,

I wrote to another member of this forum with this question as well as you.

I am about to begin welding the parts for the tug "Goliath".

I have a Lincoln 250 amp Square wave TIG welder and a 250 amp Lincoln MIG welder with a 1# spool gun.

I was thinking that I would like to weld the frames and assemble the boat using the TIG and weld the sides (1/8") and bottom (3/16") with the 1#spool gun.

I would appreciate any comments, suggestions and/or advice about doing this.
Thanks in advance for your help.

Wally

I've got a tube of DS-2000... Same stuff just a different marketing label. It's one of those products that they sell until the bad rep ruins sales then they change the name and do it again.

Don't waste you're money on it, JB Weld is a far better product without any of the risks.

Wally,
I know you did not post your ? to me but I have extensive experience welding aluminum and have constructed about (60) 14'-17' boats. YOu really have things reverse with your welding processes. The TIG welding will make a lot nicer looking weld on the 1/8" sides than the MIG will. YOu will find welding the frames and heavier members will be far easier to weld using the MIG. Using the MIG on the 1/8" corner joints, especially outside corner joints you will have to really watch it to make sure you don't burn thru.

However using either process on the 1/4" stuff will present some issues you will need to get around. Using the MIG you have the cold run-in starts, and with TIG you have to issue of getting the metal hot enough for the weld metal to adhere to the base metal. The TIG process will be very slow even when it gets hotter. With the MIG process once you get going it will weld far faster and give excellent tie-in to the base metal. Using the MIG you can use a run in tab to get the wire burning "hotter" before you start on the actual fixture. Usually a 2" tab will be sufficent. Another tactic you can use with either process is to use a torch and preheat the area to be welded before starting the weld. Either use a "temp stick" or and infrared temp indicator and don't let the preheat exceed ~200.

Another method that I use a lot is to use a 75%Helium/25% argon mix. With TIG it will constrict the arc and give deeper penetration and heat the base metal faster. With MIG it acts in different manner but it does "burn hotter". Depending on your skill level and experienc you will want to practice a good bit before you attempt to weld with it on the boat.

Good luck

I have a Little Lincoln 175 MIG that I've used for years but recently purchased a Lincoln 225 Precision TIG with Pulse, a water cooler and a 20 series torch.

I'm running 75/25 gas and find that Welding 1/4" plate is actually much easier with a TIG than with a spool gun. My spool gun is old and there's been a lot of improvements over the years so MIG'ng AL may be easier now. I would have upgraded the gun but when I weighed the cost of a dedicated Stick/TIG welder against a spool gun on an undersized welder it became pretty obvious that I didn't really have one.

One thing that I was taught years ago that helps me keep my heat correct when welding AL is to clean it then coat it with Acetylene soot. I was taught to watch the opacity of the soot and use it as a heat guide. I always make a couple of practice welds at different opacities before I select the level that I want to be at for the job I'm going to be doing.

As a side note, this is also the secret for welding tempered AL like that used on the production boats that come out of Brunswick and the likes.