I am building a 4 axis wood mill/lathe driven by Mach 3. The part I am interested in is at the bottom of the page at
http://turningaround.org/4_axis_mill.htm . It is a red oak newel post 5.75" square by 60".
The area of concern is the transition from 5.75" square to 5.5" round in .5" on Y axis and preventing tear out of the wood. Here are my asumptions
1 use up cut or straight cut .5" router bits cutting on the side of the bit so the cut is with the grain.
2. rotation speed ( A axis) at the trancition needs to be much slower than the rest of the piece.