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