Cam Design issues

[mhmizzou]

I'm working on a new cam design for a project and I'm running into some issues with the design. I used a 3D sketch for the inner side of the cam and the thicken function to extrude it out. The issue I'm running into is that the thicken function is based off the central axis so the cam face doesn't line up with the 3/8" pin that is supposed to mate with it. Would anyone have an idea as to how I can design the cam to mate better with the pin?

I've added a mock pin to the attached photo to help show the issue.

 

[3DDave]

It is complicated because the difference in offset depends on the slope of the cam.

When the slope is zero the offset is zero because the bottom tangent edge of the cam aligns with the axis.

When the slope is 90 degrees the offset is the ratio of the ID of the cam to the diameter of the follower multiplied by the thickness of the cam wall. This is because the side tangent edge of the cylinder is offset from the axis.

In between it will have that offset normal to the cam surface multiplied by the sin of the slope (I think so - sin of 0 degrees slope is 0, so the first case holds; sin of 90 is 1, so the second case holds.)

This will only be a close approximation because it doesn't include that the apparent wall thickness also increases as the offset increases. For cases where the wall is thin and/or when the diameter of the pin is small the fit will be very close. If the wall is very thick or the pin is of large diameter, the approximation won't be so good.

CNC simulation software handles this problem by taking small steps and cutting triangles and then using visual smoothing routines to hide those triangles.