Building a Bicycle Frame with Dave Yates – Day 5

Day 1 – Day 2 – Day 3 – Day 4 – Day 5

The frame may have looked finished yesterday, but there was still a lot to do! Today’s tasks:

• Frame shot blasted
• Excess brass filed off
• Any brass gaps touched up
• Excess tube ground away from inside bottom bracket
• Bottom bracket cleared with taps
• Bottom bracket faced
• Head tube reamed, top and bottom
• Seat tube cleared (27.2mm)
• Fork tracking checked
• Rear tracking and frame alignment checked
• Plug air holes (steel rod / silver)

The head tube needs to be reamed so the headset cups sit perfectly. For added precision we used the lathe's axis with the cutting tool spinning.

The cast bottom bracket already has a thread, but running the taps through cleared the thread and removed any remaining traces of the tubes sticking through.

When using external bearings, like the Shimano Hollowtech, the two outer faces of the bottom bracket must be perfectly parallel. This tool does that.

When a tube is brazed at both ends it becomes sealed. This is a problem when applying a lot of heat as the air inside expands and can only escape past the molten brass you're trying to make a joint with. All sealed tubes have to have air holes drilled but we don't want to keep these holes so they are filled with a steel pin an drop of silver solder.

These rather substantial bits of steel sit square in the dropouts and provide the leverage required to encourage the steel into perfect alignment.

So there we have it. In five days I’ve managed to build myself a fine bicycle frame. Dave is an absolutely fantastic teacher. Over the five days he only touched a tool to the frame a handful of times, and only applied the torch once, when demonstrating the more delicate technique required when brazing with silver. When teaching it can be easy for the teacher to teach by demonstration, and end up completing half the work themselves. That’s not Dave, he explains clearly and watches closely providing continual guidance.

It’s with the painter now – come back soon to see the finished bike.

Day 1 – Day 2 – Day 3 – Day 4 – Day 5