To make the cam turn the end of a bit of 3/4" bar down to 0.712" and drill & ream 0.375.
Set up the rotary table to hold the work, can be vertical or horizontal. Using say a 1/2" cutter bring it down until it touches the 0.712" dia and zero the Z axis handwheel or DRO.
Take a couple of passes at 0.025" depth of cut until you have removed 0.075" which will be the base radius of the cam and lock your head.
Now turn the rotary table say 2Deg (nothing too accurate 1/2 a turn of the handwheel) and make another pass over the cam blank
Keep rotating and cutting and you will slowly see the cam profile stary to develope
stop when you are left with 0.254" of the original diameter remaining.
See my post part way down this thread for the step by step as its the same sort of cam just in this case it is part of a gearhttp://www.model-engineer.co.uk/forums/postings.asp?th=117930