How to Gas Weld Aluminum Sheet Metal

Posted: October 31, 2018 By: MattM
Today we’re going to show you a quick tutorial on aluminum welding using the DHC Torch Kit  . We’ll be showing you the process on some thin body aluminum. These test panels here are .035 3003 Aluminum which is common in automotive body panels.
For this job we suggest running at around 4 pounds of oxygen and acetylene. You will want to set the torch up so it has a nice soft neutral flame. This torch is very good at low pressure, which allows us to do the thin aluminum panels like this. For aluminum welding you will want to the same grade (or as close as possible) as the parent material. Unlike TIG welding you will need to use a flux paste on your welding rod so you get a clean weld. You can make a little tray and rotate the rod in it before welding. This helps to keep the oxidation out of the puddle when you’re welding.
Before you start welding you will want to preheat the aluminum to help the panel get up to a similar temperature as we’re welding. On thin gauge aluminum like this you will only need to pass the flame over the weld seam for a short time before beginning to weld. Start by aiming your flame at the center of the seam and as soon as you begin to see the metal get shiny at the very center of the seam you will want to begin dipping your filler rod. Once you get a puddle going you will want to move quickly and continue to feed rod into the “keyhole” you may see. The rod should flow into the seam with easy and lay flat. If the rod is just piling up on the surface you need to slow your travel speed down, add less filler rod, or get your flame closer to the surface to raise the welding temperature. Continue to dip in and dip out like we’re TIG welding.
Once you’ve welded the seam you should have similar results as you see above. The welded side gives you a nice clean weld with 100% penetration to the backside. If you’ve gotten a nice weld with full penetration you can planish the weld with an english wheel, planishing hammer, or hammer and dolly to crush the weld and reduce the amount of grinding needed on the panel. You can also shape the metal as if it was never welded as well. Gas welding produces the softest weld and makes it extremely workable after welding. This is why so many coach builders and high end restorations shops still prefer this method.

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