Why not "braze" reinforcements on?, info from the "Welder's Handbook" Options

[SpecialK]

I was re-reading my copy of Welder's Handbook because my practice welds on some scrap were weak as hell when trying to weld 18ga to some 12ga (rosette welds) to beef-up my seatbelt attach points that rusted out. (IMG:style_emoticons/default/headbang.gif) Needed a break (IMG:style_emoticons/default/beer.gif) to do some research and find out what I was doing wrong.

The author, Richard Finch, is big on brazing automotive sheetmetal repairs as opposed to fussion welding (MIG, Arc, etc.), particularly when it involves pre '80 cars that weren't assembled using HSS (High Strength Steel). He says that the high temps involved in fussion welding actually weakens the surrounding metal, where as the lower temps involved in brazing doesn't. You can't braze butt joints like you'd use to attach outer body panels, but the reinforcement kits like Mark's (Engman) inner long stiffener's and Brad's 10ga beasts would actually be much stronger (at the attach points). His example is taking 1" x 5" long strips of .060" mild steel, overlapping the ends by 1" and brazing them together. In a pull-test machine it takes over 3000 lbs. to pull them apart and it's always the base metal that breaks, never the brazed joint. Since lap joints are the preferred joint when brazing, and all of the weld points (holes) on the reinforcements are essentially lap joints, wouldn't it make sense to braze in the stiffeners rather than MIG weld?

Or then there's always the possibility that everyone does braze their stiffeners in, and I'm just assuming they've been MIG'd (IMG:style_emoticons/default/slap.gif)


Kevin

[dmenche914]

Up the heat some (higher amps) and place a big block of brass or copper behind the sheet metal, , clamp it tight. This will serve as a heat sink, to help prevent burn thru of the base sheet metal.

Also it is easiest to weld simular thickness of metal together, so if you can change one of the parts to the smae thickness as the other, that will help.

Best advice is practice, practice, practice on scrap metal. besure it is the same kind and thickness as you will be working on, as there are different responses to welding. Do not be afraid to experiment with different settings. Be sure your wire is correct alloy, and for best results use a gas shielded MIG rather than a flux core MIG, much better results,a dn much easier to use.

i agree that brazing is not best choice for high strength applications in your car, nor bady repairs (I am trying to undo decades old braze repairs on a 356 body, yuk!!!!)

good luck dave