Crayford Focuser

grabcad

A model of a typical crayford focuser used for focusing an astronomical telescope. The model is for educational purposes and shows the components required for normal and fine focusing. Normal focusing is achieved by rotating a shaft that is frictionally in contact with a smooth flat surface. There is very little backlash with this setup. Fine focusing is achieved by a planetary "gear" system achieved with a small shaft (the Sun) and 3 large ball bearings (the Planets) rotating in a housing (Inner Gear). A typical reduction of 1:11 is achieved. The model was created in Fusion360, which has motion links to visualize the motion. You can message me if you require this file.