The basic idea behind this can best be explained this way. The cam lock can be used where you need the ability to have a quick adjustment and movement, and be able to just as quickly lock something in place.

     The hole is drilled off-center in the 1" shaft to allow it, when the handle is moved, to either pull away from ,or move in tighter to the item being adjusted.

     In this case, (B) is any backing that is solid enough to provide a clamping action of the cam. (A) would be a any bar of metal that you have need of providing an adjustment for.

     Remember to make and install the cam in such a way as to ensure that whatever force is applied to the adjusted part, will cause the cam to tighten further. Otherwise, the force can cause the cam to loosen.