More pushing the puddle...

Welding class has progressed to the point where we're actually welding things together using filler rod. It's starts simple enough: clamp to pieces of metal together on a jig in an L shape and weld them. Simple, right? Wrong. For starters, I quickly figure out that the heat from the torch warps the metal so by the time I'm halfway across your 6 inch strip of metal the two pieces no longer touch. Into the scrap heap with that one. Next up I realize I need to tack the metal at several points and then weld it. Duh. Did this several times over and eventually started cranking out some really nice tidy welds. Dare I say welds good enough looking to rival those found on bikes. Finally having some pride in my work I take it to the instructor for evaluation. He acknowledges it sure looks pretty from the outside. Then he flips it over and points out the lack of penetration. He has me hammer the piece flat along the weld and sure enough, when I hold it up to the light I see numerous pinholes. Drat. My problem is too little heat. It's tough developing the touch - too little heat yields a weak weld. Too much heat resutls in burning holes in the material. Seveal dozen L welds later I've finally got it down pat and cranking out tidy looking welds with solid penetration.

At this point the instructor has me reach higher up in the alphabet - instead of welding an L-shape now I'm going to weld an inverted T shape. Seems simple enough. I jig the work, fire up the torch and have at it. I quickly realize this is going to be MUCH more difficult. Simply changing the location of the material radically alters how the heat effects the metal. The vertical part of the T quickly heats up and begins to burn through while the base isn't even puddling. Many, many mangled pieces of metal later I finally figure out the right combination of torch angle, movement, filler rod, and oxygen/acetylene mixture.

All of this is giving me a new respect for framebuilders who have to weld numerous tubes together without distortion, too much heat, too little heat, too little filler, etc., etc. Just one bad weld can be the end of a frame. Realizing all of this I think it's something of a miracle that anyone can make a bike frame for under $500 with even the cheapest of tubing. Much as I respect the customer artisan builders I reserve even greater respect for the guys at Maxway and the other Taiwanese factories who can crank out thousands of frames in a year. It's one thing to create great welds in a small shop setting and a whole different thing to do it in a mass production capacity.