Modeling teeth on a non-circular gear
Modeling teeth on a non-circular gear
(OP)
I'm about to set out on a quest to model involute teeth on an elliptical (or other non-circular) gear. Does anyone know of an easy way to model involutes, and is curve-pattern my best bet at getting teeth to follow the perimeter?






RE: Modeling teeth on a non-circular gear
Yews a curve driven pattern would be my first choice to use. If that doesn't work you might try looking into sketch driven patterns.
Regards,
Scott Baugh, CSWP

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RE: Modeling teeth on a non-circular gear
An involute is defined by the path that the end of a string would follow as it is unwrapped from a cylindrical surface. Since your gear is non-circular, each tooth would have a slightly different involute definition based on the curvature of the ellipse at any given point.
Also, if you are modeling mathematically curvature sensitive such as involutes, be aware of a flaw in the way SW generates splines. First, sketch a spline with 3 or more points. Then, right-click the spline and display curvature. You will see that the curvature is forced to zero (i.e. instantaneously straight line) at the endpoints. You can't get a true involute definition with this condition.
Fortunately, there is a workaround. Simply sketch a couple construction lines across the spline close to the endpoints. Then, use trim to lop off the ends. You can then delete the construction geometry. You will then have a spline with ends that are allowed non-zero curvature.