I've now TIG welded a lump onto the original spindle. Bored it out to 35mm and 45.5mm O.D. Next job is to get it back in the lathe and turn it down to finished sizes. I think I'll go slightly under size on the new piece so that I don't have to press the bearing all the way down the shaft. The pulleys haven't arrived yet, but I can bore those out to 44.9mm or whatever O.D. I end up with.

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