First Aluminum Weld Project

[ericc]

I hate to say this, but this looks like the material is just plain worn out (from fatigue). Giant never intended to honor their warranty because this frame has a definite, and comparatively short, lifetime. Aluminum just does this, and Giant knows that. They hope that most customers will just throw away the bicycle before the frame fails, and all the rest they can push off with some argument like they gave you. Serious cyclists know this and buy an aluminum frame if they are short of cash or afraid of crashing. They let it go as soon as it fails, or they reach a certain number of miles, whichever comes first. It's funny; the person who schooled me on this lived in Plano, probably just up the road from you.

 

[Franko]

Thanks for your comments, Ericc. I'm pretty sure it isn't a fatigue crack. It is obviously blown out from the inside and the stress on that part wouldn't run down the centerline of the tube. No kind of strain I can think of would make such a crack.

I've seen other frames that have broken from stress. In all cases, the break was a radial crack around the circumference of the frame member.

 

[ericc]

Yeah, looking at it again and from experience, that sounds right.

 

[Franko]

This is the latest and probably last update of the split bicycle frame saga.

The split frame.



I removed the crank set and used a small hammer to push the bulge back down. I used a big drift punch with a larger hammer to tuck in some of the edges. Then I used an air die grinder to polish off the paint and oxidation. So far, it is looking good.



This is where it started going bad. After practicing on several pieces of aluminum the same thickness as the tube, I attempted to weld the split. Nothing worked. In one second flat, I burned a hole in it. I decreased the heat and when I managed to get the base metal to melt just right, the rod would ball up and not flow.

It was the ugliest weld I've ever made. I had high hopes of a nice stack of dime weld for the patch. I could not get the tube metal to flow and my welds just glumped on in blobs. I ground it down and started over a half dozen times.

It was all difficult, but the most difficult was welding next to the thick kickstand bracket. After a while, I gave up on the original plans and just ground it smooth as it would allow. It is probably ground too thin and is weakened.



I found some paint that matched pretty well. Rattle can dark copper metallic.



I had hoped to repair the bike enough to sell it with a clear conscience. I'm going to scrap it. I think I've weakened it too much to feel right about selling it to anyone.

Oh well. Live and learn. A pesky conscience can be expensive some times.

 

[Steve Shannon]

Did you flood the inside of the tube with argon while you attempted the weld?


Steve Shannon, P.E.