I'm using a Chinese built TB6560 controller it was included with the stepper motors. Controller, power supply and nema 23 stepper motors. I will post YouTube video in a couple of days where you can see my machine and the rest of it. I have it all done just need to do some editing about the rotary head. I will post a link. Thanks again.

The thing about rotary is that they are steps per degree.  Not full rotation.

For example, I have a Chinese rotary axis that is a stepper with 2 gears and a belt.
It is a 1.8 degree stepper which has like yours 200 full steps per rev.  No clue what the belt drive ratio is.  Micro stepping is at 10.

So to tune it, I started with a number, lets say 100 steps per.  
Zeroed te A axis in mach.  MDI G0 A360
Watched it rotate.  If it went to far then the steps per for A is to big.  Not far enough, then steps per is to small.
After each steps per change, you must SAVE AXIS SETTING.
Zero A axis work coordinates because it will change.  Then repeat the MDI.

Your 3.3 steps per sounds close to the right ball park.  I think I was in the 10 steps per range.

There is no logical reason why the steps per cannot be that low.  Just type it in  I just did it as 3.333 and it took the setting.