rstermer

I've seen a number of thumbnails posted on the forum of cams set up to hold material in place and was wondering if those who have made cams for that purpose could share their knowledge. How does one decide on how much to offset the pivot point from the center of the circle? What material should be used for the cam and the pivot? Any particular diameter for the pivot pin? When is it best to add a lobe to the cam and what are the design criteria for lobed cams? Do you add a friction surface to the cam face? If not, how do you get it to lock in place? What other considerations are important? Thanks for your thoughts.
rstermer