2024CADMechanismPower transmission
Helical Gear Assembly
A 3D printed helical ring-and-pinion assembly designed and iterated for smooth, binding-free power transmission.
OnshapeFDM 3D printingMechanism design
Role
CAD design, fabrication, and tolerancing
Goal
Design and 3D print a functional helical gear assembly to demonstrate gear meshing, torque transmission, and rotational motion through a ring-and-pinion configuration.
Challenge
Achieving proper meshing between the helical ring gear and pinion was the hardest part. The tooth profile geometry and inter-part clearances needed repeated adjustment across five design iterations to eliminate binding and allow smooth, consistent rotation.
Solution
I modeled the assembly in Onshape with the ring gear, pinion, and support frame each designed as separate components so they could iterate independently. I chose helical tooth geometry over straight teeth to improve the contact ratio and produce smoother, quieter meshing, then refined tooth clearances across five printed prototypes, converging on roughly 0.3 mm of radial clearance to account for FDM print expansion while keeping engagement tight enough for clean power transfer.
Results
- Final assembly rotates smoothly with no binding or slop, demonstrating helical gear kinematics in a physical model.
- Five print iterations converged on about 0.3 mm radial clearance, the sweet spot between free rotation and clean engagement.
- Unexpectedly doubled as a satisfying fidget toy, a reminder that good mechanical tolerancing directly shapes the user experience.