Spur gear pair
meshing geometry
Cosine-tooth gears at correct center distance, second gear phased so its valley meshes with the first gear’s peak.
What it is
Two meshing spur gears of equal module, different tooth counts. Tooth profile is a smooth cosine modulation of radius around each pitch circle — not a true involute, but close enough that the geometry of meshing (center distance = r_pA + r_pB, second gear phased so its valleys line up with the first gear’s peaks at the line of centers) is honest.
Why visual feedback matters
Mesh quality is something that’s instantly obvious from a top-down render and slightly tedious to reason about analytically. The "did I phase the second gear by π/N or 0?" question gets settled in one render. Tooth interference, wrong center distance, or off-by-one rotations all jump out the moment you look at the pair from directly above.
Screenshots
Parameters
Parameters 6
| Name | Default | Description |
|---|---|---|
module | 2 mm | Tooth size; pitch radius = module × N / 2. |
teethA | — | Tooth count of the first gear. |
teethB | — | Tooth count of the second gear. |
thickness | — mm | Face width. |
boreA | — mm | First gear shaft hole diameter. |
boreB | — mm | Second gear shaft hole diameter. |
Try it
- Open in your browser → openjscad.xyz, bundled single-file
- Source on GitHub →
- Full walkthrough on GitHub →