If you don't abuse it, longer than you need to care about.
See also "Rollie's Dad's Method of Lathe Alignment" at http://people.ne.mediaone.net/wasser...Alignment.html
It is *THE* way to set up and/or check a lathe. I described the technique several years ago in an article in (I think) Projects In Metal, but John's description is at least as good if not better than mine.
Try to make a living, not a killing. -- Utah Phillips
Don't believe everything you know. -- Bumper sticker
Everybody is ignorant, only on different subjects. -- Will Rogers
Law of Logical Argument - Anything is possible if you don't know what you are talking about.