Sapphire Pro CoreXY-Misalignment Fix #1 and Belt Tensioner

thingiverse

The Sapphire Pro's COREXY-geometry is not precise due to the stepper motors being situated 8mm too far inwardly, resulting in a distortion in the Y-direction. At Y=0, the error is 7.7%, causing the hotend to move only 0.923mm instead of 1mm. By Y=50, the error remains at 0.65%. Furthermore, this misalignment affects the tension of the belts. Witness this issue firsthand: Move the hotend towards Y=0 and observe the belt section from the stepper motors to the nearest pulleys. The angle between the belt and rail increases! In a well-designed COREXY-system, no angle ever changes during movement, and the relevant belt sections remain parallel to the rails. These upgraded stepper motor mounts rectify this problem. They replace the existing metal mounts and can be installed in just 10 minutes without needing to remove the belts from the hotend. The new mounts also allow for easy belt tensioning after installation. To install these mounts, follow these steps (replace one stepper motor mount at a time): 1. Disconnect the stepper motor cable. 2. Remove the two screws securing the existing mount to the upper plate. 3. Remove the four screws connecting the stepper motor to the mount. 4. Attach the stepper motor to the new mount using tweezers if necessary, as there are holes opposite three screws to facilitate screwing. 5. Insert the belt into the new mount. 6. Secure the mount to the upper plate using the inner screw, taking care not to overtighten it since it's not metal. 7. Attach the outer screw; don't tighten yet. 8. While tightening the outer screw, pull the mount against you to ensure proper alignment. 9. Tighten the inner screw carefully, avoiding over-tightening. 10. Reconnect the stepper motor cable. An updated version with more installation flexibility is now available, including a Fusion 360 file for further customization. For additional information and installation guidance, refer to https://www.thingiverse.com/thing:3982521.