Renewing Axle Cones

One of the side projects I do for bike builds is bearing overhauls.

Most folks consider cones and races to be disposable. Not here! They are only really disposable if you have a ready supply of new ones. I do not. Nor do I really want to fork over $7 for a new axle/cone set when a new hub is "only" $20.

Generally the races are good. So, it's just the cones that need replacing, right? But finding a matching new cone is troublesome too - so many combinations of sizes and depths!

Re-enter the venerable Drummond lathe. The process is simple - chuck a cone in the lathe, spin it, grind a new bearing surface on it, removing any pitting. I use the rotary tool (Dremel) to do the initial grinding.

The process also works for headset crown races and bottom bracket spindles. When I want an exceptionally nice job I will polish first with 600 grit wet/dry (and oil), then with Veritas green honing compound. Mirror finish, better than the original cast metal!

It's nice to make something pretty, even if it's going to get hidden.

None of the rotating parts on a bike go fast or hot enough to require anything more precise than a practiced hand. This isn't an perfect solution, either - the grinding will most certainly strip off any case-hardening; but, with regular maintenance further damage can be avoided.

Is it economical? Not hardly. It takes an hour or two to clean, align, grind and polish one cone or race. Even longer for races if regular cleanout is required. I've only ground out a hub once, and it was much more difficult than an axle cone.

These pictures are of a front axle cone, before (top) and after (below).