thanks, really appreciate your answer

but, I still have some questions:

1. the 4th axis digitizing wizard output is in polar coordinates. I convert this output in Cartesian coordinates. But... the ball conversion... should be do it for Cartesian coordinates. Is this correct?

2. can you give me more details about "max angle" setting? By default is 1.57. Shortest edge (0.5 by default) is clear, I think, should be the shortest straight edge on the digitized model. but the max angle, is not very clear for me, especially for 4th axis digitizing tasks

and... if you know.... there are any other application which can do this ball conversion?

kind regards,

Seb