[greenene]

I see that 99% of ballscrews are located between two parallel rails.
Can a ballscrew be mounted above or below the two rails, and what is the calculation for proper(safe) distance. In my case, I have an 24" x axis, and I'd like to mount the ballscrew one inch above the to rail.
Thanks
tc

[Al_The_Man]

More mechanical details would have to be known, for example what is the B.S. operating? Load? type of machine etc ?
Al.

[greenene]

Those questions clearly point to the fact that placing a ball screw in a non centered location relative to the two rails has its risks.
Perhaps placing the ball screw centered, but behind the support plate that holds the rails might be more appropriate.
tony

[genixia]

Gantry machine? Right?

Are you using the ballscrews with encoders for positioning or are you using linear scales for position feedback? If the former then you want as little distance as possible between the nut and the saddle/carriage because flexing in that distance translates into backlash under load. That is why most ball nuts are mounted directly to the saddle/carriage right between the rail carriages. The question as to where on the carriage it is mounted is a curious one, one that I'd answer thus: If you have 2" space above the top rail for a ballscrew, then your top rail is 2" too low. Greater distance between those rails means more torsional rigidity for the carriage.