Hello all,

I am trying to create a template for a magazine spring. This particular spring must have equations built in so that one can easily adjust the wire dia, major and minor, number of coils and the free length. I am struggling with the problem that since this is not a helical spring, I must create a oval base sketch and surface extrude to define the profile of the spring.

First I create my control based sketch, this defines my variables.

This sketch defines the major and minor, thus I create a surface extrude based on the free length:

Finally I create a helix surface based on the free length to define the intersection of 2 surfaces:

I then create the 3D intersection sketch between the two surfaces and I am left with:

But the pitch is not correct due to using a circular helix, spiraled around a 'oval' slot. Any suggestions would be greatly appreciated. SAMPLE file attached

THANKS!