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

[SpecialK]

One of the problems with flux core is the lack of being able to see what the weld puddle is doing.

For welding thin material to thick material, you must use a hot setting, concentrate the weld on the thick stuff, and whip over to the thin stuff, and quickly back to the thick. Use the trigger to control the heat if the thin material starts to go away.

John www.ghiaspecialties.com

SUCCESS!! (IMG:style_emoticons/default/smilie_pokal.gif)

I did 4 of each weld in some scrap:

1/4" hole in 18ga, 12ga no drill divot
1/4" hole in 18ga, 12ga with drill divot
5/16" hole in 18ga, 12ga no drill divot
5/16" hole in 18ga, 12ga with drill divot
3/8" hole in 18ga, 12ga no drill divot
3/8" hole in 18ga, 12ga with drill divot

I seemed to have the best results as far as a balance of good penetration and appearance (no pics, POS camera....remember the lug bolt pic?) with the 5/16" attach hole in the 18ga metal, and an approx. .060" deep drill divot in the 12ga plate. BFH tested it until I got tired of smacking it, and it held great. Never got the weld to break, but the 18ga started to fatigue around it. I'd go into a little more detail on the other size holes, but I've got to get in the shower and get my ass to work, besides they were just runner ups of the BFH smack down contest held recently in my garage.....Bring it on!

I'm gonna practice that attach hole/divot configuration a couple of dozen times before I start BBQ'n the car.

Thanks again for all of the tip guys!
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