How to "Weld" Aluminum Without a Welder

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Introduction: How to "Weld" Aluminum Without a Welder

About: I am a full-time online content creator, designing, creating and teaching the art of woodworking. I have an art background that I incorporate into my projects and focus on originality and design.

Welding aluminum is not as hard as you think. Turns out you can weld aluminum without a welder!

This instructable will teach you how to use a propane torch and some aluminum brazing rods as a quick way to bond aluminum without using a welder. It makes for a very strong bond and with a little practice can be done quickly with great looking results.

Step 1: Propane Torch

The blue Bernzomatic will work just fine but I prefer using the yellow premium touch as it's hotter and works much quicker.

Step 2: Brazing Rods

You'll also need some aluminum brazing rods. I purchased all of these things at Home Depot.

Step 3: Cut Aluminum Tubing

What I like about using aluminum is it's soft enough to cut with ordinary woodworking saw blades.

Step 4: Chamfer Edges

I'll then chamfer the edges to allow a channel for the brazing material.

Step 5: Wire Brush Aluminum

Before brazing it's very important that the aluminum is clean.

Step 6: Heat Up Aluminum

Clamp up the tubing and start heating the aluminum with a propane torch. Aluminum will start to melt at 1200deg Fahrenheit but the brazing rod will melt at around 700deg so we want to get the aluminum hot enough to melt the rod without melting the tubing. Getting the tubing hot enough may take 4 to 5 minutes. You'll know when it's hot enough when the rod starts to melt on contact.

Step 7: Braze the Aluminum

Rub the brazing rod along the channel until it's filled in and finish it off with some more heat. If you don't get the aluminum hot enough the brazing rod will just clump up and not stick to the tubing. This takes some patience and practice as my first few tries resulted in failures and ugly joints.

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    196 Comments

    0
    LarawayS
    LarawayS

    5 years ago

    Any suggestions on how to fix an aluminum boat? Just want the bottom all water tight. I used a marine grade epoxy to cover all the old seams. But I don't trust it. I've seen people use solder to fix their boats. But would it work well for aluminum? picture of the boat.

    temp_-1255580549.jpg
    0
    JamesA41
    JamesA41

    Reply 6 months ago

    Dad used Type 1 Silicone (smells like vinegar) once and lasted the lifetime + of the canoe. Just clean where you're going to apply first with a little sand paper to increase the surface area of the bond and try to get into the seams really good assuring smearing for good surface penetration, continuos sealing and bonding.

    0
    ChelseaM16
    ChelseaM16

    Reply 5 years ago

    I just repaired an 11ft tinny with major holes and cracks using 1.2mm and 1.6mm alloy patches (cut from a sheet of alloy bought @ a hardware shop) and marine silicon. cut the patch, roughen the area, drill holes for rivets (2.5 -3.5cm spacing) remove burs, cover with silicon, place patch, press hard, rivet. Works a treat - taken the boat in heavy seas at speed (hard impacts onto waves) with no leaks.

    0
    Ilan Voyager
    Ilan Voyager

    Reply 5 years ago on Introduction

    Well prepared epoxy works very well and marine grade lasts a long. You can use also polyurethane as the 3M 5200. That thing glues ferociously, remains elastic so does not break and lasts years.

    Welding is a pro task and wilh epoxy already in place it will be a pain.

    0
    devoalan
    devoalan

    Reply 5 years ago on Introduction

    well met, friend, well met. Your info on 5200 was very useful. I've used it for years, and had the horrible task of trying to remove it from wooden boats I used to restore, and once it "grows" into the wood, forget it. It is part of the wood. I just built a "bridge" or "gangplank from our back deck to the hurricane deck boat I have to use as a dock due to the government employees that need to justify their existence, and used the ISO brank to sister 2x6's to get the length I needed. Should work as expected.

    0
    devoalan
    devoalan

    Reply 5 years ago on Introduction

    HAve to agree with you on the 5200. That product, and if you want to get some at half the cost, the ISO brand urethane outdoor window caulk, which is the same formula, and a putty knife. Do all the rivets, and any cracks. It will be usable in a few hours, and will never leak there again. Want to join two pieces of wood together forever? soak the wood in water for a few hours, and then put this stuff on them and clamp. You will never get them apart or split that joint. you will break the lumber before the joint fails.and its totally weatherproof.

    0
    Ilan Voyager
    Ilan Voyager

    Reply 5 years ago on Introduction

    The 5200 and other polyurethane caulks dissolve very well with synthetic turpentine, that helps sometimes as primary to impregnate a powdery support as a concrete hole or for the cleaning or making nice fillets.

    For gluing the wood, there is no need to wet it, and you may introduce stresses in the wood by swelling/drying. Pass simply a humid sponge, a light coat of "primary" (made of caulk and synthetic turpentine) to fill the grain, let it become tacky, apply the caulk and join. Best joints are about 0.3 mm thick, but when you want an elastic joint you can make thicker until 2 mm. Let cure several days vaporizing water if the weather if very dry.

    Beware that polyurethane caulk may creep under permanent high stresses, and the joint may fail. Happens rarely in ordinary situations. That glues also very well metals and glass.

    I do agree that in most cases a good structural construction polyurethane caulk with at least 35 % elasticity will do the job.

    0
    carlitosgy6
    carlitosgy6

    Reply 5 years ago

    I can charge triple if a customer tried to fix a crack or a leak with epoxy, it mess up the weld plus i need to clean and clean and clean because is in every pore and crevice

    0
    kmcmorrow
    kmcmorrow

    Reply 5 years ago

    That's true. How to efficiently remove the epoxy that you think won't hold. Burning it off would have the EPA called.

    0
    tsturtevant
    tsturtevant

    Reply 5 years ago

    Absolutely. Tuff to remove the epoxy cleanly. At this point we're approaching buying a different boat.

    0
    elephantwalker
    elephantwalker

    Reply 5 years ago on Introduction

    I'd use a polyester fabric with a polyurethane caulk, pl/locktite poly caulk, on the seams. Just like the newer flat roof systems but better because of smaller area and the caulk is better than roofing compound. Caulk can be thined with paint thinner. Spread with a putty knife dipped in the thinner for a good surface. Maybe finish with a foam brush and thinnner to get a great surface. The epoxy should come right off with a heat gun and a putty knife. Power wire brush on a 4 in grinder with a bit more heat if needed will give you good clean surface to work on. I have used this caulk on shoes to make them really waterproof and it works very well indeed.

    If you want a " back water" fix. Take a roll of 4 mill plastic. Lay out a strip the length of the boat. Put the boat on top of plastic and pull the plastic up to the gunnels and use spring clamps to hold in place. Trim plastic and carry to water. Won't leak.

    0
    kmcmorrow
    kmcmorrow

    Reply 5 years ago

    Rent an inverter welding power source.

    0
    tsturtevant
    tsturtevant

    Reply 5 years ago

    Marine epoxy should be great. Surface prep and cleaning is the key G-Flex is great for this application.

    0
    Moose Dr
    Moose Dr

    Reply 5 years ago on Introduction

    My sealant/glue of choice is JB Weld. You do have to make sure you clean/grind off the oxide, but I've never had JB Weld fail on me. I patch from the outside.

    That said, on the next leak I'm going to try this method.

    0
    JonC3
    JonC3

    Reply 5 years ago on Introduction

    I have a similar aluminum boat. I had a small leak in the bottom and was not sure where it was located. I did some reading and watched some videos. My boat was on a trailer with motor attached. I filled the boat with water about 6 inches deep front to back. This will locate all the bottom drip/leaks. I marked where they were and drained the boat. I then used quicksteel to patch the holes and for good measure put silicone over the quicksteel after it hardened. I have no leaks now. If you follow the instructions, quicksteel works great. I have used it to stop up plastic holes with no water leaks. If you want to spend 5-10 times more money, they make really good stuff specifically for patching holes in aluminum boats. You have to get it from a marine dealer or order it.

    P.S. If you try this be careful when draining or your boat might just stand straight up!!!

    0
    LarawayS
    LarawayS

    Reply 5 years ago

    Thanks for the help bud.

    0
    Technoaussie
    Technoaussie

    5 years ago

    Although I've always had a policy That if you can't say something nice about someone, say nothing, I feel the need to point out that a lot has changed since 'Aluminum solder first came on the market, soldering aluminum is not and never will be in any shape of form 'welding' aluminum. It is just a heat joining process that weakens the tensile strength of aluminum.

    Many years ago I was one of the first professional boat builders in Australia to build a 15 ft boat completely free of any welding or riveting. It was 'glued' together and was rated to handle 65 horsepower outboards.

    I was not the only builder converting to chemical joints but the size of the ovens needed and the unique jigs you had to build to hold it altogether during curing made them quite expensive.

    Back to my reason for commenting... I supplied a 'kit' that would allow cold repairs to be made. This is what I'm writing about now. Soldering aluminum requires very accurate heat. How do you get this using a propane blow torch? With a crayon stick designed for the temperature specified to melt the solder. You put a crayon line near the solder point. when it disappears, you've reached the temperature.

    Many aluminum suppliers and more advanced hardware outlets will sell you the low temperature 'solder' and heat indicating crayon in a package.

    The bad part of using heat on aluminum is loss of tensile strength! The slower you cool it, the more strength it will retain but once heated to the point where you solder it, all sorts of often dramatic things can happen.

    A much stronger and distortion free way to join aluminum is to 'glue' it together. The thermal setting adhesive used to equal the strength of aluminum itself is hard to find in DIY amounts and I doubt Mum would be very happy to find letterbox being bonded in her oven but there are plenty of 'cold bond' 2 pack adhesives on the shelves that will (when properly used) give you greater strength bonds with no likely hood of separation as solder joints provide.

    0
    TigerTom
    TigerTom

    Reply 5 years ago

    Which is the best "cold bond" 2 pack adhesives do you suggest to give me a greater strength bond with the aluminum i am bonding for a fence gate outdoors?

    0
    Technoaussie
    Technoaussie

    Reply 5 years ago

    Hi Tom,
    If you can you tell me where in the universe you live it will help determine what is most suitable and where you can get it. The summer and winter temperature will help too. The people who supply me, tailor mixes to suit climates but they also have mixes for exterior use that can be mixed to be secure in below freezing or extreme humidity but unfortunately not one single mix for both climates.

    I've got plenty myself I can probably give you some if you live in Australia. Sending it overseas can be a problem sometimes but I believe its available in most countries.

    0
    JamesA41
    JamesA41

    Reply 6 months ago

    @Technoaussie I'm wondering about methods for taking a non-functioning horizontal shaft pressure washer mount ear and grinding to fit the ground seat of a functional horizontal shaft pressure washer mount ear that was broken off during shipping and missing. Thinking welding will be best. Though wondering about adhesives now reading into this. Thinking most of the load will be the rotational force and an adhesive may be all that is required. However, what's the best COTS is another question to deal with the thermal expansion and contraction? Figure summer operation spring, summer and fall operation primarily in Michigan... though the extreme temperature of the cast aluminum engine block transferring heat to the cast aluminum (I guess at least) pressure washer casing is more my concern.