An SPR is being filed.
Turns out the Wrap feature is also corrupt. A curvature analysis makes it pretty clear that the ends are not merging correctly with the continuation around the cylinder.
The same curvature analysis with the arc wrapped around the cylinder showed no artifacts.
I made the precision absolute at 0.00005 (doesn't change the results much).
...and with the Wrapped curve from equation...
Lesson learned... don't wrap equation curves around cylinders! Hopefully PTC will fix this in Creo 2.0 and 3.0.
This has some pretty serious implications in areas where equations are being used for turbine features wrapped onto cylinders or cones.
However, even with a single iteration, there are problems that we normally live with. This is back to default accuracy (Relative 0.0012).
This is the curve itself... near perfect:
And then the surface created to create the edge needed for the normal control for the spring below...
Although for most of us, these small errors are less that catastrophic.
Awareness of the fact that cumulative error will have consequences is something to take note of.
On another note, I would be remiss by not providing a solution.
Attached is a Creo 2.0 spring that uses the cylindrical curve from equation. The Pro|WorkAround^TM to the twisting problem is in a surface sweep.
Sweep has a normal to surface option that is not there when the sweep is not generated from a surface... such as the equation curve.
A 4 family table versions of the accurate version is attached...
Driving parameters
