yes, and I would NOT jump at the chance to do it again...it was a PITA. I doubt any *real* machinist would put up with the nonsense required to do it for you, but if you have a lathe and patience (and are really bull-headed) it can be done.One trick that was suggested (after I had done it my way) is to use a bolt "lock- nutted" and extending out the top to chuck the piece in the lathe...better idea than chucking the quill end which requires you to hand-finish that end. Watch your knuckles and for interference with tools...it's *not* a piece that conforms to best shop practice.
Realistically: I think it will be easier just to find a 21.1mm (better known as .833") stem on eBay or at a swapmeet.