Quote Originally Posted by Robin Hewitt View Post
Profile rails come in 2 flavours, those that screw from above, those that screw from behind.

If you screw from above, swarf and grit can sneak in passed the grease wipers on the ends.
Depending on make you can buy top mounting with covers to stop this. Don't mean the Green caps like Hi-win but full metal strip that clips into the rail.
Not cheap put that's what you'll find on many industrial VMC's that use Linear rails.