Centerlines are saw blade movements on the Y Axis (vertical movements - up & down). All Retro C component saws contain one of two versions depending on the generation of the saw.
The centerline encoder is the counter that tracks the position of the vertical movement. The centerline encoder is located either on the end of the shaft for the (older) Joyce actuator style or on the end of the shaft of the gearbox (newer style) behind a gray cover.
When doing calibration on a saw head one of the things you will need to do is verify the max and min values. The Centerline moves up and down via a motor and chain and is only stopped because the motor mount bracket can’t move any more because it is stopped by the saw frame.
The purpose of this article is to explain how to tighten the centerline slide enough so that vibration does not allow it to move during setup while allowing it to move during normal operation.