CAD for Spiral Cam

[Ether]

Originally Posted by Ether

Why did you choose these particular equations, instead of, say, varying the radius of the spiral linearly with angle, like this?

If you want a spiral whose radius starts at r=r1 at angle=0 and varies linearly with angle until r=r2 at angle=alpha, the polar equation for that would be:

r = r1 + (r2-r1)*(theta/alpha)

For example, if r1=1, r2=1.5, and alpha=2pi, your equation would be:

r = 1 + (1.5-1)*(theta/(2pi)) = 1 + 0.5*(theta/(2pi))

See attachment.