Drilling The Brake Levers              

 

My drilling jig - not too fancy or complicated :)  Perfect for hand drilling!

During my drilling of the chain ring I discovered that countersinking bits are excellent for starting a hole.  Unlike drill bits which tend to "walk," countersink bits stay put.  The key is to use a "single flute" countersinking bit and very, very slow drill speed.  The single flute countersinking bits, as compared to multiple flute bits, are much easier to control, and they remove material slowly but cleanly.

After I started a hole precisely where I wanted it, I drilled through it with a drill bit.  And the final step of countersinking (a/k/a counterboring, which is really the more correct term in this case), was very simple: very light pressure, very slow drill speed, and in about 3 turns of the bit (per hole), the countersinking was done.

I sure wish I'd known about using countersink bits to start holes when I was drilling the chain ring - it would have been a whole lot easier and the circle pattern would definitely look better.  But unfortunately I didn't even know countersink bits existed!  How embarrassing :)

UPDATE:  Gary Watts wrote with the following information: 

A countersink is a tapered recess, a counterbore is a flat bottomed recess.  Flat head screws go in countersinks, socket head cap screws go in counterbores.  For example, the stem fixing bolt on the Cinelli 1A is a socket head cap screw (basically) and the machined feature in the stem is a counterbore.

Thanks for clarifying that for me Gary!