Lesson 11: Cam Mechanism
Goals
- Understand cam mechanisms and design them in Fusion
- Understand oscillating crank mechanisms
- Convert rotary motion to reciprocating or oscillating motion
1. Cam Mechanism
A cam converts rotary motion into linear (up/down) motion. The cam shape determines the output motion pattern.
- Eccentric cam: Smooth sinusoidal motion
- Heart-shaped cam: Constant velocity rise and fall
- Custom cam: Design any motion profile with splines
2. Oscillating Crank
A four-bar linkage that converts rotation into oscillation:
- Crank → Connecting Rod → Rocker → Frame
- All connections use revolute joints
- Link ratios determine the oscillation angle
3. Comparison
| Feature | Cam | Oscillating Crank |
|---|---|---|
| Motion freedom | Any profile via cam shape | Adjusted via link ratios |
| Part count | Few (cam + follower) | More (crank + rod + rocker) |
| Karakuri use | Up/down, nodding | Arm swinging, drumming |