Goal: To create a 1-12 2A external thread on a shaft using the swept cut feature.

What has been done: I have created a fully defined closed 2D shape of the thread profile [sketch13]. I have created an open 3D sketch of a helix [Helix/Spiral1]. Using the swept cut feature, I click on the closed sketch for the profile and the helix geometry for the path.

Problem: I  get this lovely gem >

Question: Why is this happening??

Thanks