Terry Neilson wrote: > This clears up some Questions that I have been wondering about. I was > referring to the accumulated error in the ball screw, not backlash. The ball > screws that I have are decent ground ones, so they should be ok. I'm not > worried about thermal expansion, that usually only comes into play on runs > longer than I will be doing. > I appreciate the info, I wanted to make sure I was going down the right path > before starting this project Many large, high-end machining centers have shaft encoders either on the leadscrew or on the motor. I'm talking about $100,000 machines. Some of them offer an upgrade to linear encoders at substantial extra cost. So, given decent ballscrews in good shape, shaft encoders can perform quite well. And, if long-term errors are a concern, you can map the error and enter it into the compensation tables. I have been REALLY satisfied with my Bridgeport conversion. The only source of error I know of is that the table and saddle are worn, and the slides no longer move in a perfect straight line. I get a few thousandths of an inch of curvature in parts. For the work I do, this is usually of no concern.
Jon ------------------------------------------------------------------------------ This SF.net email is sponsored by Sprint What will you do first with EVO, the first 4G phone? Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
