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.
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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
There are lots of people who mistake their imagination for their memory. - Josh Billings
Law of Logical Argument - Anything is possible if you don't know what you are talking about.