CoreXY

CoreXY is a two-dimensional motion configuration used in Cartesian gantry systems for devices such as 3D printers, laser cutters, and desktop CNC routers. It employs two fixed stepper motors that drive two separate belt loops. The belts are arranged on a rigid frame and connect to a single carriage that slides on two linear axes. The routing forms a closed belt network with pulleys at the frame corners and on the moving carriage, allowing the toolhead to move in the X–Y plane while the motors remain stationary.

In operation, the position along X is produced when the two motors rotate in opposite directions, while the position along Y results when the motors rotate in the same direction. The kinematic coupling between motor motion and Cartesian movement provides decoupled X and Y axes, which helps achieve higher speeds and accelerations with relatively low moving mass.

Compared with the earlier H-bot arrangement, CoreXY offers improved rigidity and reduced skew and racking because the belt segments act on both axes. It requires careful belt tensioning and alignment and can be more sensitive to pulley and belt tolerances; calibration typically includes setting belt tension, square frame, and verifying linearity.

Typical implementations place two motors on the frame, with two belts routed around idlers and attached to a carriage that carries the toolhead. CoreXY designs are popular in open-source 3D printers and small CNC machines because they enable fast, precise motion without moving the motors.