How to Solder Aluminum.





Introduction: How to Solder Aluminum.

Up until recently I didn't know how easy it is to solder aluminum with a propane torch. The torch I'm using has a broad flame so it's probably not as efficient in heating the specific area for welding. A torch with more of a pin point would do better. In either case if you have a propane torch and brazing rods you can weld aluminum. All this can be found at your local hardware store. The rod cost about $3.00.

Step 1: Get the Right Rod.

In the same isle where all the stuff is for arc welding you'll find aluminum brazing rod. I got mine at Home Depot. It has a working temperature of 700 to 750 degrees Fahrenheit. A propane torch burns hot enough to get the job done.

Step 2: Clean Your Joint

Any time metal is being fused together it's always best that you clean it off. Long story short, clean metal sticks to clean metal. I'm using a wire brush on both surfaces. Now you're ready for some heat.

Step 3: Brazing Aluminum.

Apply the flame to the joint until it's hot enough to melt the rod. When you sweep the tip of the rod through the joint it should melt in. If not, heat the joint more and check it again with another sweep. You want the metal to melt the rod not the flame. When everything is cooled off you'll have a strong joint. Check out the last picture where I tried to pull the joint apart in a vise. The metal got all bent up before the joint failed.



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Nicely done instructable. I do want to try this to make some 10" aluminum lawnmower blades for my electric mower.

Please don't! At its best, aluminum is prone to fatigue cracking; a brazed, soldered, or welded aluminum will fail very very quickly. This is asking for a large shard of aluminum embedded somewhere very painful.

That's a good point. I only wanted to do this because aluminum is so much lighter than steal. In theory, the aluminum blades(2) would require much less energy from the motors to turn. Thus, the blades might spin faster and/or the batteries would last longer per charge.

Lighter blades would only take less power to initially spin up. Once spinning the mass makes no difference to the power needed to keep it spinning. That is down to air resistance, bearing friction and how easily it slices through the grass.

Thanks nophead. You have given me something to consider.

let me know if you die

The only way an aluminum blade would work is by anodizing it specifically hard coat Anodizing, which drives the price up so I could not see any advantage. My experience with hard coat is extensive mostly being an Automotive Mechanical engineer where we used this process a lot, especially to prevent wear and add Lubricity to Transmission Valves.

Scott @Steamworks

steamworks1960, Your comment is most appreciated. I am somewhat familiar with anodizing from the aircraft world. However, I've never herd of hard coat anodizing. Interesting. Cost is always a limiting factor in manufacturing no doubt. If cost wasn't an issue, could small lawnmower blades be fabricated to allow battery powered mowers to perform better? Perhaps even more exotic materials like carbon fiber/kevlar, carbon boron etc could help. Or a laminated blade with all of these would perform best. I just want more performance. In every other motorized device out there, reduced mass combined with equal strength produces higher performance.

Although you "could" do that, as Jissan mentioned it is too soft for the cutting edge so you would need to use stainless fasteners to bolt on hardened steel blade edges.

Considering this extra complexity, weight of fasteners, pain cleaning grass off to swap them, AND that steel blades made specifically for the purpose already exist, it would be a silly thing to do.

ac-dc, you make a solid argument. It accrued to me to add a steal leading edge to the blades to aid in cutting. The steal blades would need to be thin and have holes to allow them to be mounted and replaced when they wear down. I still think there might be some performace gains from a lighter mower blade. Perhaps a composite of aluminum, kevlar, carbon fiber, and steal would create the ideal light weight but strong blade.