Hi all,

This is my first post here, so please excuse me if my question is naive.  I'm working to create a design table driven feature in a part, and thought that I had it working well.  But, after coming back to it, I seem to be unable to change any values in the design table without creating invalid sketches and ultimately invalid features.  I'm using SW 2010 SP5 on a Win XP64 machine.  The file is attached if anyone cares to take a look at it.

I'm creating a spiral arm (not a helix, it starts from a 2D spiral generated by solidworks) between an inner and outer ring.  My procedure is as follows:

1) Create  Spiral via Helix and Spiral curve button.

2) Create a sketch from that spiral by creating a new sketch plane and using Convert Entitites on the spiral.

3) Continue in the same sketch by roughly drawing in a spline with end points on the same inner and outer ring surfaces as in the creation of the spiral.

4) Add construction lines between the converted curve and the spline, and make each line endpoint coincident to it's respective curve/spline, perpendicular, and of a fixed length equal to all other similar construction lines.  It was my thinking that this would keep the spline and curve mostly parallel throughout their entire length, and works well for a single iteration.

5) Finish the closed sketch by adding arcs to connect the curve/spline endpoints points along the diameters of the inner or outer ring as necessary.

6) Use the design table to control: a) spiral start angle, b) spiral # of revolutions, c) spiral pitch, and d) length of construction lines (spiral arm width).  Items b and c are related to each other through the differences in inner and outer ring diameters, and I have setup an excel formula to populate the pitch based on the # of revs.

Originally, I could change values within reasonable limits in the design table, and regenerate new geometry without errors.  However, when I opened the part yesterday, I couldn't make any changes to the # of revs without it causing an error in the curve/spline sketch.

Is there a cleaner, less convoluted way to make parallel splines, or mor specifically, make a spiral curve between two rings and then make another curve parallel to the first, then connecting the endpoints into a closed sketch?

Thanks,

Adam Hartman

FlexMedical

Plano, TX