welding a motorcycle gas tank without warping

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A friend of mine is doing a custom gas tank for his wifes Harley and asked me to weld a big patch panel on the top of it to get rid of all the factory console junk on it. I am worried about it warping. It has to be seal welded so it won't leak. Should I tig with Er70s? Braze? Is there a better tig rod to use than er70s? Doesn't need to have a lot of tinsel strength it just has to handle vibration and not leak.
Reply:Originally Posted by chadcooper55A friend of mine is doing a custom gas tank for his wifes Harley and asked me to weld a big patch panel on the top of it to get rid of all the factory console junk on it. I am worried about it warping. It has to be seal welded so it won't leak. Should I tig with Er70s? Braze? Is there a better tig rod to use than er70s? Doesn't need to have a lot of tinsel strength it just has to handle vibration and not leak.
Reply:Originally Posted by weldermike70s, and you'll be fine bud, iv'e done them for a long time. Just go short passes and move. If its a top patch there is going to be filler on it anyway to blend it out for paint. So if it does warp it leaves you a little mallet room.
Reply:Have you considered suggesting some sort of steel design in that space?  If you can put an eagle, snake, cross, etc. over the patch area it will create a lot of margin for errors on the bare flat space.Hobart LX235Victor 250 Oxy-Acetylene Rig (welding and cutting)Bobcat 773F-350, 1999, 4x4, 16' 10K# trailerOutdoor Wood Burner - 10 cords/year
Reply:Originally Posted by gwileyHave you considered suggesting some sort of steel design in that space?  If you can put an eagle, snake, cross, etc. over the patch area it will create a lot of margin for errors on the bare flat space.
Reply:I have harley guys bring me tanks all the time. It seems like the brazing always end up leaking eventually for some reason. So i sand it down and tig it with SIB (silicon bronze). I prefer that over stainless. I can usually run about 40A instead of 55A with the Er70 rod. I would definitely go with the silicon bronze rod. Practice before you use it on the tank you will be surprised how easily it flows into the metal being welded. Silicon bronze also sands really easily so you can build it up and sand it to contour with the tank.Miller Dynasty 200Millermatic 211Instagram?.... find me @ WELD_MEDIC
Reply:Tig it with 70s2 and it will be fine... it will warp a bit and you won't be able to grind it perfectly smooth, but that is why body filler was invented.
Reply:Originally Posted by tig_21I have harley guys bring me tanks all the time. It seems like the brazing always end up leaking eventually for some reason. So i sand it down and tig it with SIB (silicon bronze). I prefer that over stainless. I can usually run about 40A instead of 55A with the Er70 rod. I would definitely go with the silicon bronze rod. Practice before you use it on the tank you will be surprised how easily it flows into the metal being welded. Silicon bronze also sands really easily so you can build it up and sand it to contour with the tank.
Reply:make sure to tell him get 1/16, not 3/32...
Reply:Originally Posted by weldbeadmake sure to tell him get 1/16, not 3/32...