B/S Acme R&P

[lgalla]

Another which is better or cost effective.
Acme's are 30% efficient,ballscrews 90%.I read somewhere ground ballscrews are made with machines with acme screws???Does anyone like their acme screws?Is there an efficency rating on R&P?On the THK online store a rolled ballscrew,25/05 is$217for2000mm and $154 for the nut.Is this cost effective compared to R&P?I guess my confusion is the huge differences in pricing on these units depending on source.
Larry

[RICHARD ZASTROW]

Larry, Make sure you are comparing apples to apples and both apples are Macintosh. There are ballsrews (rolled in various degrees of accuracy and ground in various degrees of accuracy) ACME leadscrews Cut (ditto) & ground (ditto) & rolled (ditto).

Then there is the "corrected" ACME you speak of that is a "MASTER". Those were made by removing any errors left after original machine manufacturing. Some are scraped, lapped or whatever it takes to get them as near to perfect as possible. The very best are kept as "artifacts" to which others are compared for error. The old SIP leadscrew comparators had a cam on the dial to move the pointer to compensate for the known error in the machines leadscrew. Clever stuff dating back 100 yrs.