So I have created a worm drive and everything is looking okay except that the ends of my spiral or helix seem to finish abruptly. I want to create a chamfer on the ends of the spiral teeth so when you look at the shaft from the side, the spiral finishes with a cone shape at each ends.

This is what I have currently.

I'd like to get the end to look like the bottom left on this photo.

Could anyone help me with this?