Need Help!- When to move to R&P?

[Drools]

What is the width limit of a machine using THK HSR25 blocks and rails, that a ACME screw or ballscrew can be used without encountering racking?

Thanks

[LazyMan]

If you design your gantry rigid enough and space the bearings apart sufficiently you should have no problem with a single driven X axis with a full gantry with 4 to 5 feet of travel. Screw whip would be the concern more than 4ft long.

[Drools]

Thanks LM, I'm looking at using 3/4" thick Ali at a width of 8" for the gantry uprights. I could use the long versions of the bearing blocks to make things even more rigid.