a midway bikelog

I’m working on building a bike trailer from a couple of bike frames diverted from the scrap heap. Today i chopped off the front-end of each frame – actually sawed off the downtube at the bottom bracket shell and un-brazed the top tube at the center-of-the-seat tube lug, in hopes of re-using that lug connection later. To get the brazed joint apart, i just heated that joint until i could pull the tube out*. The frames are small step-through frames, so the top tube is roughly parallel to the downtube. Here’s a photo of the Schwinn frame after cutting and unbrazing:

The tubes are parallel, and intersecting a tube at a right angle, so the miter should be perfectly in-line with the tube. You can see that the Schwinn work is a little off. The tube didn’t deform on removal, it was just mitered crooked and brazed in anyway. You can see the difference between the brass from the lug point and the center of the curve of the miter. Here’s a shot of the same miter on the Huffy Free Spirit:

Yeah, even worse. Not only is the miter crooked, it’s only for maybe half of the tube. You can see the outline of the lug point where the centerline of the tube is, and the miter is almost 1/8 of a turn away. Sheesh, even i can do better than this. The joint was relying pretty much entirely on the lug for support, and that lug is a fairly thin piece of mild steel. With this sort of workmanship, Huffys are better off being welded.

* As i’d heard from a couple of sources, taking a brazed joint apart doesn’t work very well. In both cases, the lug deformed and tore when i pulled the tube out, presumably from overheating it to get the brass to flow again. I was hoping to change the angles and re-use those lugs for a crossbar, but i might just end up welding or filet brazing that bar instead.