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Spot welding with an Oxygen-Accetylene Rig

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#1 ·
Hey guys. The inner fender repairs are moving along quite nicely (although slower than I would like) on my '65. I welded on a new fender to cowl brace last night and am VERY pleased with how it turned out. I bought an oxy-accetylene rig several months back, and other than practice, this has been my first chance to use it to weld something important with. Anyway, the cowl to fender bracket is held on with spot welds, so I had to work on a technique to do something similar without a spot welder.

First, I drilled out the old spot welds with a spot weld cutter. Word up. The spot weld cutter to have is the "professional" one that Eastwood sells. It's made out of HSS and looks about like a pointed router bit. The ones NPD sells that have teeth are good for about 2 spot welds each before they become so dull they are unusable. After the spot welds are cut, you can pry the parts apart with a stiff paint scraper.

Then I primed the mating surfaces. You might want to use weld through primer, even though you aren't going to weld through it.

Then I put the new bracket into place and drew a circle everywhere I wanted a spot weld. I also put a dot between the circles where I was going to put in temporary rivets to hold the bracket in place and firmly down.

I drilled 1/8" holes at all the dots and 1/4" holes at all the circles...just in the bracket, NOT through the inner fender or cowl. I also used the 1/4" drill to chamfer the 1/8" rivit holes.

I put the bracket in the correct postition and drilled the rivet holes the rest of the way through...wallowing the bit a little to get the right diameter for an 1/8" rivet.

Using a swivel head rivet gun (Eastwood) and 1/8" rivets, I staked the bracket firmly into place. Then I used an 1/8 drill bit on my electril drill sort of like a grinder...moving it around the 1/4 holes to remove the primer underneath and expose nice clean shiny steel.

OK here's where I'm going to lose some credibility.

I cut a steel coat hanger into straight pieces to use as a welding rod. That's right coat hanger. It's thin, it's clean, and it flows very well. I tried it because it was recommended to me by a welder with 40 years experience. It worked 10 times better and easier than the welding rod I used prior to this.

Then I put water soaked towels all around the area to be welded on the car.

Using a 0 tip, 10 psi accetylene and 20 psi 02, I got a slightly carburizing flame (adjust O2 until inner blue cones line up, then cut 02 back a litte to prevent oxydizing flame). Best results were with a flame just loud enough to hiss...maybe 2" long.

Then I put the flame into the 1st quarter inch hole, heating the steel behind of it pink, then red, and as it went molten I started flicking the tip back up on the coat hanger to start a puddle in the 1/4" hole. I kept the tip moving to prevent burning through and get the edges of the hole molten. I kept adding wire until the hole was completely filled and even slightly over filled. Finally I took the rod away and used the tip to puddle the whole surface flat maybe 1/2" in diameter.

I paused between each weld to let the piece cool and prevent warpage...and moved from side to side on my welds working from the outside into the engine bay. After all the 1/4" holes were firmly welded, I turned the torch on the rivet heads and puddled them while adding just enough rod to fill the hole and bring it slightly above the level of the bracket.

The final step was to spend about 45 minutes with a die grinder taking everything back down flat.

I didn't take any pictures, but it looks really good and is down better than stock. What I mean my that is that when I drilled out the factory spot welds, there was hardly ANY penetration.

Anyway worked for me. Might work for you.

Good luck if you give it a try.

Phil

'65 Convertible (with many mods.)
http://www.blueriver.net/~finite/Pony.htm
 
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#2 ·
Good job Phil...
Next time you have the opportunity, try backing the acetylene pressure off to 5-7 psi and the oxygen to 12-15 psi and see what happens....

Coat hangers have been used for welding filler for as long as I can remember....as long as they're the plain wire ones...*G*...I have even used them with TIG when in a pinch in the field....

Good heads up on the cutting tools....good American made HSS or cobalt tooling is always what I suggest, especially when working with metal that has been slightly hardened by welding...
Yous gets what yous pays for....*G*

About the only down-side of the gas torch is the amount of heat it puts into the parts because the flame temp isn't as hot as an electric arc....but you controlled that well with the damp rags...

I know I don't have to remind you but for others, it's a good idea to have a fire extinguisher nearby when welding inside the car....not in the car but within easy reach...



Pat
http://albums.photopoint.com/j/View?u=1570936&a=11937754&p=42910787.jpg
 
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