Linear rails, also referred to as linear motion guides
and linear slides, are common motion components used to achieve smooth sliding motions. They can be found in 3D printers, CNC mills, waterjet cutters, and the like.
A linear rail consists of a stiff, steel rail, along which a carriage slide. Most commonly, the carriage contains recirculating ball bearings that provide contact points between the carriage and the rail, as depicted above. This enables a smooth sliding motion as the balls roll between the surfaces. The shape of the shaft enables the carriage to stay locked on with tight tolerances, restricting the motion to strictly linear directions.
Linear rail 3D printers utilize the numerous advantages of these linear rails to, supposedly, achieve better motion. So, how plausible are these claims? Let’s take a look.