In article .com,
says...


I am presently using a Parabolic curve because it has the largest
minimum radius of curvature and lowest contact stress of all the
standards curves my cam design software can produce, i.e., Harmonic,
Modified Sine, Modified Trapezoid, Cycloidal, and the "standard"
Polynomials (3-4-5), (3-4-5-6), (4-5-6-7), etc..

Since this is a low speed mechanism and you don't need to worry about
acceleration, jerk, etc., I'd forget about all the standard cam
profiles. Isn't the curve with the largest minimum convex radius a
constant radius? The minimum concave R only needs to be larger than the
follower. I'm talking about the outer cam here.

Like this...
http://www.suscom-maine.net/~nsimmons/news/Cam.jpg

The .379 radius, which is what you need to maximize, is dependent on the
angle between the dwells (the shape of the cam is fully defined without
the .379 dimension); 20 degrees in this example. Making the radius of
the convex part of the rise smaller lowers the contact stress.

But maximizing the radius will probably not result in the lowest stress,
since it appears the force on the follower varies quite quickly with
displacement. Is that correct?

Ned Simmons