Base Circle

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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. 


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Base Circle formula

\(\large{ BC = PD \; cos\left( PA\right)  }\) 
Symbol English Metric
\(\large{ BC }\) = base circle \(\large{in}\) \(\large{mm}\)
\(\large{ PD }\) = pitch diameter \(\large{in}\) \(\large{mm}\)
\(\large{ PA }\) = pressure angle \(\large{deg}\) \(\large{rad}\)


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Tags: Gear