You cannot cut the keyway with the lathe attachment. Well, you probably could, but it would be easier to hammer bamboo sticks under your fingernails.
Ideally, you would have a friend with a mill large enough to cut it in one pass, but if not, you could set it up and cut the keyway in sections.
My next question was going to be about how difficult it would be to cut that keyway. I have a bench-top mill, and also the milling attachment for the South Bend (and I guess there'd be no problem running it without a lead screw for a while).
It seems to me that a huge amount of precision wouldn't be necessary, but it would be a whole new operation for me, and therefore a bit intimidating. What would be the best way to hold the screw in a vise - rigidly, but without damage? In fact, what would
the whole procedure be? (I got the "do it in sections" part.) That screw is probably hardened, right? So, carbide cutters? A milling saw if I can come up with one? Anyone know the dimensions of that keyway?
Or is this dicey enough that I should just wait until a 9B leadscrew surfaces on eBay? (It's a 36" six-speed - the absolute cheapest model one could buy. My dad bought it new...)
Thanks for the input - I really appreciate it!
South Bend 9" Model C, Walker Turner drill press, Rong Fu table-top mill, "Mini" lathe, a whole bunch of Shopsmith gear