The track itself consists of a pair of linear rods, with the torch mounts sliding along on linear bearings. A lead screw sits between the two linear rods, and is powered by an old cordless drill ...

Plastic versus ball bearings. Standard ball bearings have point-to-point contact with their supporting rails; in contrast, plastic linear bearings have a much greater surface contact with their rails.

Thomson MultiTrac Ball Bushing bearings permit steady-state travel at up to 10 fps and accelerations to 450 fps2 in linear-motion systems.