I'm just starting my second machine using thk linear rails. Work envelope is about 30" x 5'. Is it worth the effort to mount the x rails on the bottom side to protect them from dust and debris. Will be used mostly for wood, and a small amount of alunimum. I've seen this discussed before, but can't find the thread.
Seems if you mount them on the topside, the ball bearings will constantly be plowing through saw dust.