3D printing is a process where an object is built up by thin layers. The 3D printer needs to move back and forth along the length of the model to create those thin layers. If the printer loses its position during that back-and-forth motion, the 3D printing process will no longer be aligned, and the 3D printed object will be ruined. The high repeatability and reliability ensure the printer does not become misaligned during the back-and-forth movements.