hi jaru-eri :)
this perfection depends on cnc accuracy ( available & output ) and backlash management
even if you have a pretty accurate cnc, you should still consider to control :
... axis reversal ( near the top of the sphere )
... accuracy value
example of backlash management functions, for okuma :
... ( variable ) lost motion compensation
... pitch error compensation
... reversal spike auto-adjustment
example of accuracy control, for okuma :
... in-position parameter
... nurbs
... allowable errors in radius comp & in circular interpolation
... acceleration / deceleration
also, a complex shape requires moderate feedrates, because higher values will lead to deviations
i am afraid that you won't obtain a nice sphere if you go like that
pls check video shared in this post :
... roughing is done on each half
... part is rotated with 90*, and roughing is repeated
... if you wish, you may repeat the process also at 45 90+45 180+45 and 270+45 degrees
... part is rotating during the pre-finish and the finish operations
obviously, turning seems to be more indicated, or at least a vmc with 4th axis :)
do you wish to know how balls of bearings are turned ? there is an insert for hard turning, and the ball is between 2 centers with spherical surface; in the end, the ball is reclamped in a rotated position, so to turn the material that was making contact with those spherical centers at the previous operation
if you wish only to experiment, you don't need expensive tools :) no ....
all you need is to adjust the cutting specs : for example, if you clamp a tool and it has 0.04tir, simply don't use a finishing feed > 0.04 / does it makes sense ? consider feed=60%tir; if you go like that, you should end up with a nice smooth surface
if the surface is smooth, uniform, than measure spherical tolerance, so to see how close you are to a sphere : in this moment, if you are not satisfied, repeat the process with a higher quality tool ( from better carbide, with better coating and with better goemetry ), and clamp that tool with less tir : now you should see better results :)
kindly :)
https://www.youtube.com/watch?time_c...&v=NwOtZnjqKGA