Originally Posted by scarlson

You may need a mighty good lathe and some tooling you don't really care about. Those BB axles are normally harder than a coffin nail!

I have a bunch of no-good axles and no-good cups and I have access to the lathes that could do it, and I still won't - readily available sealed BBs are going to be lighter, stronger, smoother, and more durable, plus you won't have to machine hardened steel.