Got a start on Matt's frame yesterday and I'm fixing to get back to it as soon as I absorb this cup of coffee. I know I've posted a hundred of these bottom bracket photos but its how I start out on a frame, actually it starts with the drawing but this is the first actual building that I do. I just like to start out with a perfectly tight miter and the level lets you know you're vertical, although the level doesn't prevent me from taking a crooked picture. If you look close you can tell I don't have the camera perfectly straight. Thats ok though, I'm not a photographer, I'm a frame builder. This foundation is true. Onward!
This is the stock dummy axle slider from Bringheli and it has a neat little measuring stick attached in order to measure your bottom bracket drop but since BMX frames have a bb height instead of drop I had to have an attachment to my jig made, it was shown in some earlier posts a while back. Without having a way to know where the bottom bracket was sitting in correlation to the axle center I had to figure out a way to measure it. And the next picture shows you how I did it.
At first I was just gonna measure up from the floor but thats not really an accurate method for something that needs to be precise so I just mounted this level to the jig and measured down to the bottom bracket center and the rear axle center to get the difference. The bottom bracket is gonna sit 1 7/8" higher than the axle center and when I'm eyeballing the jig the axle center looks much lower than that, its not, 1 7/8" on the nose. I think I measured it about a hundred times.
Paragon stainless track dropouts. Top shelf components. Alright back to work. Chao amigos.