Help with ‘zipshape’

Hi,

I’m trying to work up a grasshopper definition that takes a curve, offsets it a user-defined dimension, then generates a ‘zip’ or ‘teeth’ through the centre of the two curves.  I’ve tried a few variations, but each seems to lack the sophistication to generate a ‘zip’ that retains its general shape over the whole curve.

Basically I’m trying to understand the process behind this: http://www.schindlersalmeron.com/index.php?option=com_content&t...

Here is an image of the latest definition. 

1.      I draw a curve in Rhino, and then define it in grasshopper.  I also define the point as the beginning of the curve.

2.      I offset the curve to a specified depth, based on structural member

3.      I generate a line from the point at a tangent to the curve, then rotate it a

defined angle.

4.      I find the intersection between the rotated line and the offset curve.  Then generate a tangential line from this new point

5.     Line is rotated at the same angle as before.

6.      Process repeated.

The idea is to then generate a circle of defined diameter at each of the intersection points, then find the intersection of the circles with the curves, which are then joined up with straight lines to create the ‘zip’.  This would mean a lot of copy-pasting and list management that I’m not really capable of with my limited grasshopper experience.

I had tried generating points at intervals along the curve and then eventually generating lines from one line to another with a shifted listed to form the tooth angle, but it wouldn’t retain its shape over the entirety of the curve.

Does anyone have any advice for how to tighten up this definition?  I imagine that I will need to delve into vb.net scripting to address the recursive nature of the process. 

I fear that I’m going about this in entirely the wrong way...

Of course the next step is to flatten out the curve for CNC manufacture.

Any help would be greatly appreciated! The potential for using grasshopper in design is amazing, and I would love to gain a deeper understanding of it!