Patience is Everything When Milling

I believe that I have figured out the gCode to cut a centered circle in the 1.00" x 1.00" workpiece.  When I used a piece of acetal, it worked well cutting .01" per pass at 25 inches/minute.  In carbon fiber composite,  that jerked the workpiece out of the vise.  Even 5 ipm introduced too much vibration.   Cutting .001" per pass at 25 ipm, seems to work okay.  

If I was doing this manually,  even assuming that I could accurately turn both X and Y axes at the rate for circular interpolation,  it would take too long to do.