Variable Helix

I’m trying to add a Helix to a screw that has a MIN thread depth that runs at an angle for 11.2mm, and then runs out straight for the remainder of the shank.
I have attached a snip of the drawing. The line highlighted orange, is the spline i am trying to run the helix along.

Any idea on how to get it to follow this spline?


This is a typical job for a radius by law curve.
I have attached an NX12 example.
The sketch is the law for how the radius evolves. The total length ( the X- direction) of that sketch is = 100% of the helix height.
i.e if you make this say 100 mm and the helix should be 14 total, and the “bend” at 7 mm, the sketch should bend at 50 mm. ( I hope you understand this.) the height from the base line is 1:1 to the selected radius/diameter in the helix dialog.

You should probably add a fillet ( possible even a G2 Spline ) in the sketch between the lines , else the helix might have a sharp corner which in turn might affect the sweep you do on that helix.

Above is a snippet.