Introduction: Quick and Easy Brazing Aluminum, Copper and Nonferrous Metals
Brazing is a quick and inexpensive alternative to welding. The equipment in this project can be bought for as little as $30 dollars. Brazing is also much easier then welding, it's a lot like using a glue gun. Brazed metal can also be stronger then welds. And for personal projects and small production runs, brazing is much more cost effective.
In this instructable I'll show you how to fix a bicycle kickstand, make bi-metal candle sticks, show you a few examples of other things you can make. There's a lot more you can do, this is really easy and I hope this will get you started.
I think many instructable projects on this site could be simplified with this technique. Basically, with any project where you want to make something strong out of metal like aluminum or copper. A couple ways you might use this include mechanical uses like adding a foot to a bicycle kick stand, making a bicycle cart or part on a lawnmower, and uses in electronics like soldering copper to aluminum to a solar panel backing. Brazing is just great for a lot of things!
Brazing, means melting an alloy to join two metals. There are a few different brazing systems out there. My favorite is low temperature brazing using an alloy called HTS-735-II. It brazes at low temperatures and makes it easy to connect all sorts of metals and the welds aren't brittle.
* Propane torch
* Low temp fluxless brazing rods (These are hard to find so I listed a couple places people can get them.)
- Alumiweld 730 rods from Harbor Freight Item #44810, they cost about $14 bucks for an 8 pack. To braze a kick stand you might use 1/4 a rod.
- You can buy pounds for around $35 a pound from alumiweld.com this is where Harbor Freight orders from.
- Or HTS-735-II welding rods can be ordered from these companies in US and a UK seller. These companies charge around $70 for a pack, so it's not the best deal though this is what I used in my projects.
* Protective Gloves
* File or steel wool to clean the joint surfaces.
* A brick or steel can or tray to braze on.
* Metal pieces you want to connect together like: aluminum, magnesium, zinc, brass, copper...
* Not for food grade applications. Having called the manufacturer of the Alumiweld product, they said they are not selling a food safe product yet, though they will be. So I'll update this instructable when they do. But with the current product I wouldn't let the product have prolonged contact with skin or food since I don't think it's designed for that.
If you do want to join pipes for food applications here is an easy to use product for that purpose:
#450 Soft Silver Solder
96.5% Tin / 3.5% Silver
Melting Point: 430° F
"Use: Ideal for electrical work, utensils, and dairy and food equipment."
* There are two methods I use for welds, melt and blob methods. Both are described in their own section.
* I use the term "welded" instead "brazed" a lot for a few reasons. First it's common language and people who are starting out with this will be confused by technobabble. The Second, I use the term "welded" because that's how the product I use describes itself.
* This is low temperature so there aren't a lot of fumes or uv light dangers. I often use this indoors, though a garage with good ventilation is probably recommended.
* The weld point tends to be stronger then the base metal, if the metal is aluminum or copper. So you can fill in gaps like dents in propellers and holes or cracks.
* The alloy I'm using here can be used at sea, it won't disintegrate from electrical differences. So you can fix propellers and things with this.
* Making an odd sized nut. Because this alloy does not stick to iron or steel screws, you can melt it onto an aluminum or brass washer and build it up around the threads. Then give it a twist with a wrench, it comes free and you have a nut.
* Making bushings or custom threaded screw holes. This is also usually hard to do. But if you have a piece of steel you can put in a hole and you fill around the hole with this stuff, this alloy won't stick to the steel so when you take out the screw you had in the hole you will have a it will make a threaded screw hole. If you used a smooth steel bolt then you will have a close fitting bushing. Though the hole will be tight so you may need to sand it if you want to use it as a bushing.
* FYI I don't sell this welding product and I'm not associated with the companies that do. This technique is just cheap, easy and awesome! Enjoy!
Step 1: Melt Brazing - Making Candle Sticks
My first weld type I will describe here is typical "Melt Brazing". It's just heating the metal then touching the metal with the brazing rod to see if the rod starts melting everything together. In this example I'm making some candlesticks welding copper to aluminum. Typically that would be very difficult to do, but with this system it's very easy.
Step 2: Melt Brazing - Making Candle Sticks Part 1
Select the materials for your project.
Here I cut two pieces of aluminum stock metal (2’ x 3’ x 1/8’) and picked out some copper 3/4' adapter pipes.
Step 3: Melt Brazing - Making Candle Sticks Part 2
Here I’m heating the metal on a heat resistant surface. I’m heating both pieces with a hand torch and rubbing the brazing rod against the metal. When I'm not applying heat, I touch the metal with the brazing rod to see if it will melt. When the rod starts to melt then the metal is hot enough. So I’m wetting the copper and the aluminum with this melted metal, like melting a crayon. Then I'm applying a little more heat so everything melts together.
Step 4: Melt Brazing - Making Candle Sticks Part 3
Then I let the parts cool, it's best to let the metals cool slowly in the air. Then I test the welds.
Step 5: Melt Brazing - Making Candle Sticks Part 4
Then I clean up the copper with fine "0000" polishing steel wool. Salt and vinegar can also help to clean it up. Then I file off any burs and it's good to go.
This is about as easy as soldering, but works on metals that don't easily accept solder. In fact if I was soldering copper to aluminum or aluminum to aluminum, this would be my preferred method since it requires no flux.
Step 6: Blob Brazing - Bicycle Kick Stand
Here I'm adding a foot to a bicycle kick stand so it doesn't sink into the grass. Most kick stands are aluminum like this one so here I'm brazing aluminum to aluminum. I call this the blob method because the alloy is melted and applied as a blob. This is my own method, though I'm sure other people do it too.
Step 7: Blob Brazing - Bicycle Kick Stand Part 1
I briefly filed the surfaces of the kickstand since it wasn't too clean. Then I broke the alloy stick into segments and put them in place to melt with the flame as I heat up the metals. Also I'm moving the metal pieces a little to be sure the alloy gets everywhere it's supposed to. Though if the pieces are secured in a vice then I'd just poke the blob with an unbroken alloy rod to move the metal around if needed.
Step 8: Blob Brazing - Bicycle Kick Stand Part 2
Here you can see the metals melted together by the torch. This is very strong. This upgrade took about 1 minute of time to set up and get the metal in place. Then another minute of cooling time.
Step 9: Some More Examples
Here are some more examples of both melt and blob brazing methods. Each example is challenging in it's own way, but possible using this brazing method.
* Cup: This cup is made from a discarded can. The metal is very thin so I cleaned it and used the blob method to braze a handle onto it. Though keep in mind that this cup is plastic lined as contact with this particular alloy is not intended for food use.
* Coin: This is a coin for a magic trick. I used a blob welding method, but blob or the touch & melt method would work. (Note: The depicted big-y coins are not us-currency.)
* Bushing: This is a powder cast brass bushing. It would be easier to use a copper tube, but if you wanted to weld on a bushing like this it's not too hard. It is saturated with oil so first you need to burn the oil with the torch. Then position it and braze it. After the item has cooled, polish it and oil it.