Autodesk Inventor
The blue "line" is your circle profile on edge view.
The purple curve is the Helix.
Notice that the blue line is not perpendicular to the start of the helix.
The orange "line" is a Workplane created perpendicular to the start of the helix.
very few people catch this mistake that results in incorrect geometry.
Re: ball pattern in BALL SCREW assembly
I am using 2013 - so you would not be able to open my file even if I posted it.
In this image there are two circles - the 6mm circle you used with Coil to cut the face shown in orange.
I cut back overtop that feature (red) with a 5.99mm circle and notice that it cuts the sides more even though the circle is smaller.
My circle is perpendicular to the helix, yours is not.
I made a mistake earlier when I said one solution was Natural on the start of the Coil. That is the default. You would need a flat start to have the circle perpendicular to the coil curve. But don't use that technique unless you start the Coil well off of the part, and in any case it will give you results that are harder to understand than simply doing a Coil surface of a line and using the edge of the surface body helix for a Sweep.
