Open CAD demo
A 40-tooth chainring you can open, inspect and edit
This is the same deterministic project behind the PurCad home-page model: a parameterized chainring concept compiled by the production OCCT geometry path and saved as a ready first version.
The brief is bounded by dimensions, not appearance alone
The demo starts from a compact mechanical brief: one flat ring, 40 repeated teeth, a 50 mm center bore and four 10 mm mounting holes on a 104 mm bolt circle. Those values remain attached to the project instead of being hidden inside a decorative mesh.
The first version keeps the important inputs inspectable
PurCad creates the demo without spending generation credits. Opening it makes a normal project in the signed-in user's Library, with Version 1, visible dimensions and the same editing flow as any other project.
| Parameter | Demo value |
|---|---|
| Tooth count | 40 |
| Concept module | 4 mm |
| Bolt circle diameter | 104 mm |
| Bolt holes | 4 × Ø10 mm |
| Center bore | Ø50 mm |
| Plate thickness | 2 mm |
The preview is rendered from built geometry
The evidence image below is generated from the current OCCT preview mesh, not drawn separately for this article. Orthographic shaded and wireframe views expose the outline, holes, thickness and any disconnected geometry.
- Geometry check
- The compiled result is one closed solid with no disconnected component in the preview mesh.
- Built envelope
- The current OCCT bounding box is approximately 168 × 168 × 2 mm.
- Project handoff
- Open demo creates Version 1 and then selects it in the normal editor; the project remains available in Library for that account.
What this demo proves — and what it does not
It proves that PurCad can carry explicit dimensions through a deterministic DesignIR into a real OCCT solid, a checked version and the normal editor. It does not prove chain engagement, fatigue life, material strength or bicycle compatibility.
Concept geometry, not a riding componentThis is not a certified bicycle drivetrain component. The simplified tooth profile is not validated against a chain standard, and the 2 mm plate has not been engineered for riding loads. Use the project to explore the workflow, then apply the correct standard, material, tolerances and qualified testing before any physical use.