Cam groove Design

[JVD2]

Hi all,

With trying to 3D model a Cam profile from an old 2D drawing i'm stuggeling with the dimensions of the Radius of a profile. See picture attached. I can't seem to figure out what way these R should relate?
It is a constant velocity profile for a follower of 22mm. I can't seem to get an complete contained sketch...
Anyone got experience with cam profiles?

Kind regards,
JVD

 

[Compositepro]

I have little experience with cam grooves but this appears to be a simple geometry problem. The roller (or pin) must stay in contact with both sides of the groove at all times for positive control of its path. The inner radius of curvature at a bend in the groove can be zero or greater. With zero radius the roller acceleration in changing direction will be great (theoretically infinite) and cause "jerk". Increasing this radius will result in smoother motion. The outer radius of curvature of the groove will equal the inner radius of curvature plus the roller diameter. The center of the radius of curvatures will all be the same point.

 

[Jboggs]

All the radii in any curve should be concentric with each other. Think about it. As the cam roller travels thru that curve, its center point follows a circular path around a specific center, which means all the points on that cam also follow circular paths around that same center. Just draw the cam at various points around the curve and you'll see what I'm saying.

 

[gearguru]

Do not forget about the functionality of that cam. The parts connected to the follower (22mm roller) will move as the CENTER of that roller moves.
Therefore: create the lines/arcs of the path which the roller's center will follow (I guess that they are properly dimensioned on the old 2D drawing, I see that there are some vertical "center" lines limiting the beginnings and ends of arcs/lines of it) and - imagine a cylindrical tool of the 22mm diameter to move with it's center along that path.
It is basically the same what already Jboggs said. I am just making you aware about what is most important here: how the center of the follower moves...