Problem with Intersect (knife) - making extra cuts in mesh I am trying to make a thread around a cylinder by cutting faces at the intersection. The cut tool makes extra vertices and connects vertices in random places.

I also tried using the boolean intersect and I get the same result. The tools are not creating a clean cut into the mesh.

Here the link to what I am trying to do.. Making thread

This video is what I recorded and the problem I am having. Intersect (knife) problem



This is the result that I am trying to get.
Looks like you forgot to move in the face that is used for creating the screw object; you can see that it is moved in slightly in the first GIF of your link, intersecting with the cylinder. If you don't do so, the screw object is on the same face level as the cylinder, which will cause the problem you encountered.