Crack in my wine glass I am doing this tutorial to make a wine glass with the spin tool. After applying the spin tool, a subdivision surface modifier and the solidify modifier my glass looks like in the image. Somehow I did something wrong resulting in a "crack" in my wine glass. When I did this process again I am sure that I set the spin tool at 36 steps and 360 degrees. What did i forget ? Hope I did not ask a question that what was already answered



here is the blender file
It looks like you have a face inside the glass wall, the subsurf modifier does not handle this kind of non-manifold geometry very well.

Look closely, see the face within the wall.


To get rid of it just go into wireframe view and select the spare face and delete it with Del > faces.


Edit:

I looked at your .blend file and since in your particular case you are using a solidify modifier to get the glass thickness you can't directly select the offending faces and delete them.  Just go into edit mode and select all with A, then hit W > remove doubles.  This will merge the duplicate vertices along the crack.

Here is a comparison:


See how before I removed doubles, when I selected the edge loop at the location of the crack only have “tails” in one direction?  This means there are double verts at that location.