TOM Z-min Endstop

thingiverse

The Thing-O-Matic features an issue that often causes frustration: inaccurate Z-height calibration. As the Z-endstop travels to the top and descends approximately 120mm to find the build platform, any change in temperature or humidity can lead to slight wood expansion or contraction, causing a 0.1mm deviation between the nozzle and the platform. This discrepancy may seem minor, but it significantly impacts raftless printing where layer adhesion is critical. However, this problem has a simple solution: a direct Z-endstop contact with the build platform ensures consistent nozzle height regardless of thermal expansion. Proceed with caution when modifying endstops and nozzle heights, as there's a risk of damaging your bot. For this fix, design around a heated build platform (HBP), ensuring that no part protrudes above the surface. Follow these steps to implement the solution: 1) Attach an endstop to the printed block using M3 screws. Optionally, you can remove the current Z-endstop and use it for this purpose. Exercise caution when handling the nozzle to prevent accidental damage. 2) Remove the metal switch lever from the endstop to avoid print damage. 3) Detach the left M5 screw that secures the extruder, then position the block on the Z-stage as shown in the provided images and reattach the bolt. Ensure both the block and extruder are securely fastened. 4) Connect the endstop cable to the endstop and route it to the motherboard. If necessary, extend the cable with a splice. 5) Calibrate the setup by ensuring the nozzle tip is 1mm below the endstop button. Adjust the OpenSCAD file's "e" value if needed. Position the build platform in front of the nozzle and lower it until the endstop triggers, then raise the platform slightly under the nozzle. Record your Z-offset (-1.0mm for mine). 6) Replace your start.gcode with the provided one, customizing it as needed. Save your new Z-offset in the motherboard and test print a simple part while monitoring the process. Adjust the Z-offset as necessary to perfect layer adhesion.