The only way to get 1 mil absolute accuracy is with a closed loop system and absolute encoders. Screws aren't that accurate unless you are willing to pay for high quality ground ballscrews. And in reality you don't need 1 mil accuracy for pic n place.
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Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
Vist my websites - http://pminmo.com & http://millpcbs.com |