Hello,

For the limits:

Look at the first picture, if there are no limits the tool with down in Z to cut the side of the model as in the bottom picture. ... and you get a hole at the joint after a full revolution.

To get a correct overlap, it's not the width of the part or of the width of the limit that is important but the fact that the right and left side overlap FOR THE PERIMETER SIZE. (sorry, difficult to explain in English)

On the second picture, the green arrows show the perimeter for a 40 mm model (125.66mm), that mean that the model must be created for a given diameter, in other word, the model must be identical at the left and right for this perimeter value. It's the same that for texture in 3D.

No sure it's more clear

++

David