Trying to make a 1.316 Diameter ball on a SL-30 Haas Lathe with a .375 round cutting insert. I want to make one single pass.
A 0.375 radius is very big. If you start with 1-3/8" diameter round bar and try turning a 1.316" diameter hemisphere on the end it is likely you will get a lot of chatter. Trying to turn more than a hemisphere will almost certainly cause a lot of chatter.
An open mind is a virtue...so long as all the common sense has not leaked out.