I am currently useing a linear guide but soon will be changing back to just a shaft ( or tube) with ball bearings mounted on the top and sides of a carriage to guide my bridge. The plasma generates a lot of dust and dirt that keep me cleaning the linear rails and bearings often. When I don't clean the rails the dirt accumulates in the linear bearings and causes enough drag that the stepper motors slip and I then lose accuracy in the cut. The simple bearings didn't give any trouble but I thought linear would be better, I was wrong,Oh welllllll live and learn. Besides you can save some big bucks with the ball bearing/shaft method as opposed to the linears
never set a pace that you can't maintain
Traveler