For my first machining project, I CAMed and machined a 7-component Geneva Drive mechanism using a CNC mill and lathe. The Geneva Drive is a rotary indexing mechanism used to convert continuous circular motion into intermittent rotary motion, like in old film projectors.

Design Process

The mechanism had seven main parts:

1. Geneva wheel

2. Geneva round

3. Base plate

4. Shaft for Geneva wheel

5. Shaft for Geneva round

6. Driving pin

7. Knurled handle for turning

CAD/CAM

I designed and generated toolpaths for the CNC parts in Fusion 360:

• Adaptive clearing for the Geneva wheel slots

• Contour passes to get the driver's curved blocking surfaces

• Profiling ops for the star shape of the driver

• Basic facing and drilling for the base

• Simple turning for shafts and the knurled handle

• Press-fit holes for bearings

Machining

Split the work between:

• CNC mill for the Geneva wheel and driver

• Manual lathe for shafts and knurled handle

• Manual mill and drill press for the base plate

• Press-fit operations for the bearings

Results

The mechanism worked smoothly - one complete turn of the driver indexes the Geneva wheel exactly one position. The knurled grip made it satisfying to turn by hand. Most importantly, I learned the basic CAM workflows and machine operations I'd need for future projects.