Base Circle formula |
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| \( BC \;=\; PD \cdot cos( PA) \) | ||
| Symbol | English | Metric |
| \( BC \) = base circle | \(in\) | \(mm\) |
| \( PD \) = pitch diameter | \(in\) | \(mm\) |
| \( PA \) = pressure angle | \(deg\) | \(rad\) |
Base circle, abbreviated as BC, is a circle from where involute portion of tooth profile will be produced. The base circle of a gear is an important concept in gear geometry. It is a theoretical circle that is used as a reference in the design of involute gears. The base circle is defined as the circle from which the involute curve of the gear tooth is generated.
