There’s a lot of chat in the framebuidling world about brazing, about welding. That’s the cool bit, for sure, the bit that a lot of folk live for. It’s the magic alchemy part of the whole operation, where disparate becomes inseparable, where molten metal is coaxed into form. Without a doubt, it’s my favourite part of the process, and I think the same is true for a lot of people.
And yet, it’s probably not the most critical part of the process of building a bike. I’d suggest that it’s the mitring that determines the success of the result to the greatest degree. Tubes are mitred so that they fit perfectly, each tube immovable against the next. That is the thing that makes the bike straight and strong more than anything else. There are many ways to mitre tubes: you can cut them with hacksaw and file, or a holesaw in a milling machine, or, like I do most of my mitring, with an abrasive tube notcher.
I still file some joints by hand, still cut some of my notches with hole saws, but my tube notcher is my favourite. I won it in an auction, and a little while back I machined up this fixture for it that securely holds a tube. The fixture works with tubing blocks, allowing me to do mitres on either end of the tube perfectly in line with each other, or perfectly at ninety degrees, for the downtube. I can easily set the mitre angle for any geometry, necessary for my full custom process.
It’s the little things like this that take so long to make, yet pay for themselves so quickly in an efficient and accurate process. This is just one of those things that you can’t see or feel at the end when you ride your bike, but have been integral to the building of your new bike.