I do a lot of fancy parts for bikes. I want the bikes I make to turn out just as I imagine them. Each one differs from the last. The problem with each bike being different is that it’s often not worth making tooling. This time it was worth it.
I’ve been using yokes for my mountain bike construction in the last few years. I’ve gotten away with free-handing seat stay yoke struts but the last set got all messed up. I swore to ensure that it wouldn’t happen again. I need a high degree of precision in this part so I can have the strut meet the seat tube just off of tangent. There is very little room for error.
This new tool will allow me to weld a variety of strut segment diameters and angles to the yoke (or something else) in a very accurate way. I spent a while thinking and iterating this fixture. I didn’t want to waste my money or time on something that would be used only once.
In the shop, the tool works very well. It’s super solid and very easy to adjust the smallest amount. More than anything else, it’s very precise. The press fit center pins and the locating pins give a sturdy location to measure positions to within a thousandth of an inch. Better still, the part is held securely while welding either side so distortion is highly minimized.
Once the struts are welded, they get mitered to the seat tube.
Here, 0.070″ shim is used to vertically center the strut to the yoke. As a variety of yoke and stay sizes are used, this seemed like the most sensible alignment technique for this parameter.