scarlson 

Thanks!

Yeah, we discussed dressing it up with a couple more passes, but decided it wasn't necessary! Time better spent having a drink and a chat.

I have done a fully dressed-up/invisible repair on a French constructeur frame that shall not be named at this time. Aesthetics just weren't a huge deal in this instance, and may have even been the enemy of a job well done. Also, holy merde, if you'd seen the size of the crack I'd need to fill after I finished grinding prep! It was like the grand canyon! Again perfect for pipeline-style welding.

I wish I'd taken pictures along the way, but conversation with friends was more fun/important. I had to grind out most if not all of the adjuster hole, because the metal was so distorted and greasy in those fine threads, even after acetone and a wire brush I wasn't confident I could get it clean enough not to form voids and get brittle. I had a big gap to fill! I clamped a thick copper backing to both halves of the dropout (copper won't get involved in the weld), separated by the required a-little-more-than-10mm for the axle to slide in. The gap to fill was about 3/32" at the bottom. Laid a root pass down (tie into one side, then the other, don't heat up the copper backing!), ground, filled it up with a finish pass or two (apply more heat on the finish pass to penetrate in and tie the whole thing together), then put the copper backing on the other side and did the inside. Then I did a bunch more filing to get things flat, and we properly spread the frame using the Sheldon Brown technique with a piece of lumber braced against the seatpost. I'd forgotten my alignment tools, so I did a rough job with calipers and a crescent wrench. BTinNYC did the final alignment when he got home. A rough guide for alignment is also to feel for dropout flex when you tighten the quick release. If you feel the dropouts flex as you tighten the QR, it means they're conforming to the axle, and aren't parallel to those faces.

I think the original failure was caused by a combination of things. The wheel was spaced at 130, but the frame was spaced 126mm. The frame hadn't been spread, instead it was just sprung apart (making for a lack of alignment when at 130). I think the dropouts are pretty hard metal, and the modern axle didn't have very aggressive knurling on the end of the locknut. These factors (DO misalignment, lack of dig-in) combined to allow the axle to slip forward and diagonally, and then I think the tire caught up on a chainstay, brake, or seatstay, bringing it to a sudden stop, and the momentum of the rider was brought to bear on the bottom of the dropout, the wheel wanting to remain at rest and the rider/bike wanting to go forward.