For example, detailed gear teeth look nice in an exploded view for a parts catalog, but add unnecessary regeneration time to higher-level assemblies. A cross-section of a gear looks odd if it shows detailed teeth—particularly helical teeth. Any assembly requires an extra assembly constraint to orient the gears so that the teeth mesh correctly. Although the assembly of two detailed gears looks peculiar, how can you represent a mesh of two mating gears without it? How can you be sure you’re looking at a gear mesh and not at an interference? How do you know it’s a gear and not a doughnut?

The following procedure addresses all of these issues using a family table and a simple internal cut in the model to represent the tooth area. The example below models external gear teeth, but the technique for internal teeth is similar.

The generic instance named R12345 has a simple representation of the teeth with the root diameter. This instance is used for assemblies and cross-section views on drawings. This instance regenerates quickly, which is desirable in higher-level assemblies. The family table member R12345_TEETH has the detailed representation of the teeth. This instance is used for the isometric snapshot view on drawings, parts catalogs, and anytime a view of the actual part with detailed teeth is desirable.

Generic: Simple Representation of Teeth

1. Start with a protrusion representing the blank size of the part, using the major (outside) diameter of the gear.

2. Create chamfers, undercuts, and any other geometry that alters the shape of the tooth.

3. Create a revolved doughnut-shaped cut using the gear root diameter as the minor diameter. The remaining sides of the cut are created by offsetting the existing edges (including any chamfers, etc.) into the part 0.05 mm.

4. Name the cut GEAR_SIMPLE. You may need to add descriptive terms when you have more than one set of teeth (for example, GEAR_SIMPLE_EXT or SPLINE_SIMPLE_INT).

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