Question about Blend with a hole in a circle, and a cylinder.

 From: bemfarmer 11 Nov 2012  (1 of 7)
 Attached is a simple sphere, with a hole created by boolean difference of an extruded ellipse. There is an offset cylinder inside the hole, with one end inside, the other end outside of the sphere. Did a Blend of the sphere hole edge, and the end of the cylinder inside the sphere. Also did a similar Blend with t he outside end of the cylinder. I was expecting the surface to be tangent to the sphere, but instead, get a "bulge" at the edge of the cylinder hole. The bulge can be adjusted with the Blend slider control. (The bulge does have a nice shape, which I like.) The question is, why is there a bulge, instead of a tangency to the sphere? (Flip did not seem to make any difference.) EDITED: 10 Aug 2013 by BEMFARMER Attachments:

 From: blowlamp 11 Nov 2012  (2 of 7)
 5540.2 In reply to 5540.1 I think it's something to do with the sphere being a solid. I used the Separate tool on it and hid the resultant inner surface - it would then blend at a tangent for me. Martin (2).

 From: Michael Gibson 11 Nov 2012  (3 of 7)
 5540.3 In reply to 5540.1 Hi Brian, yeah somehow your sphere piece is not just a single sphere surface but is instead something like 2 surfaces stacked up on top of each other and joined together. Or I'm not sure if the second surface is exactly stacked on top of it or maybe it's some kind of degenerate "trimmed down to nothing" kind of thing. At any rate, it's that second unwanted surface that blend is trying to match to - when you blend with an edge that is joined between 2 surfaces is it kind of random which of the 2 is actually taken to be the surface to blend to. So to help control it you usually want to blend between unjoined edges only, with an unjoined edge there is only one surface that owns it and so blend will behave more predictably there. To get rid of your unwanted other surface here, select the sphere, do Edit > Separate on it, then select all the pieces that you want to keep and then invert the selection and delete the weird unwanted piece. - Michael

 From: bemfarmer 11 Nov 2012  (4 of 7)
 Here is another shape derived from the basketball: EDITED: 10 Aug 2013 by BEMFARMER