So, I got a free frame that someone claims water froze in the chainstay and it burst, leaving a small crack. I think is true because the crack has forced some material outwards, and when I took the BB out, water poured out of the frame and all the seat tube was all wet when I took the seatpost out. Anyway, I didn't do it but I since the frame was free I thought it would be worth experimenting with a repair.
So, anyway. I'd like to repair this frame and ride it as a commuter/round-town bike. By far it's the most new-fangaled bike that I've ever had, and the only aluminum one too. I didn't pay for it so I can't just "Get a new frame" as everyone commonly suggests with these sorts of threads. I'm not sure I'd buy a new aluminum bike in the first place... anywho.
Here's my plan for the repair.
Drill stop holes at the ends of the crack to help stop its spread. File away the material that "burst" above the surface when the chainstay opened up.
Clean off all the surrounding paint and clean the area thoroughly.
Now, I have either two options. TIG weld the crack and then fabricate a sleeve and then weld the sleeve to the chainstay to reinforce the whole area. Judicious use of heat sink clay would hopefully minimize the damage from heating the frame up with welding.
The other option is to do the same repair, but using HTS-2000 brazing rods. I like this idea, but they almost seem too good to be true... but I'd basically follow the same procedure as with TIG welding it.
Here are some pictures: