I just got this ball screw from an eBay auction:
http://cgi.ebay.com/ws/eBayISAPI.dll...MEWN:IT&ih=017
I'm going to use this for my z-axis. My question is how can I turn the shaft down to install bearings? I see that some guys say that the shaft is too hard to machine. What I was thinking of doing is turning the shaft and using a grinding stone on a dremel and than using a file or fine sandpaper to get a tight fit (I do not have access to a lathe). It seems like there should be a better way to do this, but I haven't been able to find any.