Getting height difference of a conical helix?

I’m trying to model the top cone of a self tapping screw, as pictured below; with it’s threads consuming around 2/3rds of it. The thread pitch is 1.75 mm.

I successfully followed this video (link), that demonstrated on how to create a conical helix.

I would like to obtain the height difference, between the green circles in the image below.

I was able to use multiple guide lines and the protractor tool, but adjusting the height of the helix with the scale tool, would require me re-drawing the guidelines.

I was wondering if there was a quicker way of achieving the task?

This is the .skp file: 025_conical_helix height thread pitch.skp (1.6 MB)

Anything in a selection gets scaled.
If you group the helix, leaving the guides out, the guides won’t scale.
If the guides are inside the group, or if you select them with the group, they will also scale.

1 Like

Thanks that worked.

I’d like to add, that the best way to adjust the pitch, is at 5:20 of the tutorial.
026_self tapping screw.skp (2.6 MB)

This was the best I could achieve.