gear 3d model

Create a dimensionally accurate mechanical compound spur gear, not a decorative or stylized model. The part is a replacement focus-drive gear for a Canon EF 50mm f/1.8 STM lens. Create two coaxial involute spur gears as one solid part. Upper large gear: 27 teeth, 8.12 mm outside diameter, approximately module 0.28, 20-degree pressure angle, 1.0 mm thickness. Lower pinion: 9 teeth, approximately 3.08 mm outside diameter, module 0.28, 20-degree pressure angle, 3.0 mm axial height. Both gears must be perfectly concentric and share the same rotational axis. Add a centered cylindrical upper support pin, 2.0 mm outside diameter and 2.4 mm height. Total part height must not exceed 6.4 mm. Add a centered 1.15 mm diameter axial hole through the complete part for a 1.0 mm shaft. Teeth must be functional involute gear teeth with uniform pitch and accurate tooth count. No bevel, no helical teeth, no smoothing that changes tooth geometry, no decorative details, no text, no chamfers unless extremely