It is traditional for sheldonbrown.com to post an April Fool’s day page, but this year we couldn’t think of one that wasn’t either frivolous or, if it addresses the present situation, dark humor and potentially offensive to people who have lost friends. We do have this:
Sheldon Brown alone on his Moulton, September, 1971.
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“The Dynohub’s bearing cups are integral with the hub shell, and can’t be replaced.”
This is true, as far as the original cups formed in the central hub. They are extremely hard and cannot be cut with ordinary lathe tools.
I used a carbide cutting tool and Tap Magic® cutting fluid to cut into the badly spalled cup recesses to accept sealed conrad ABEC-1 ball bearings. As the ones readily available at an industrial bearing supplier in a suitable bore diameter had a smaller OD than the cup recess, I made adapter bushings of hard aluminum alloy to take up the space. I had done this before to adapt sealed bearings to a Campagnolo Nuovo Tipo front hub, so I had a little practice.
I considered making “cones” to support the sealed bearing units so that I could use the original axle, but instead made a new axle drilled through for a quick release skewer.
In hindsight I could have avoided the difficult cutting of the bearing cups by making a pair of spacer bushings contoured to fit the cup.
After building a front wheel using an aluminum rim for my Speedway 500 5 speed around-town bike, setting up a headlight and taillight, this hub served me for several years before being stolen. Braking was far better than with the original chrome plated steel rims.
I think that Speedway 500 was an Azuki, a secondary brand of Nishiki from Louisville Cycle & Hobby, the shop’s primary supplier.
The above was around 45 years ago.
That is quite a machining feat. Back in the 1980s, I went a different way and machined an aluminum shell. Now I would just buy one of the modern generator hubs.