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!

Replies to This Discussion

Permalink Reply by Wiktor Kidziak on February 2, 2011 at 4:18pm

Hi Victor

I am very interested in your experiments with ZipShape. Did you manage to start a new thread about it? I can not seem to find it... Thanks in advance :)

Permalink Reply by Victor Leung on February 2, 2011 at 9:06pm

I'm sorry that I have not yet, but I will very soon, hopefully I could find some time in the Chinese New Year. Thanks for your interest. I'll keep you posted.

Cheers

Victor

Permalink Reply by Victor Leung on February 3, 2011 at 4:01am

Dear Christoph, Wiktor, Cristian, Ryles,

I will post the project on my own website here: http://www.dreamationworks.com/?p=163

I will post the project in three parts, part one is up there. Thanks for the interest, cheers.

Victor Leung

Permalink Reply by Cristian Luca Atzori on February 3, 2011 at 4:40am

You are approaching the problem in a very interesting way.

Also, it seems that you enjoy very much any kind of geometrical problem ;)

Thanks for sharing!

Permalink Reply by Victor Leung on February 4, 2011 at 8:06am

Yes, I do,

Perhaps as a student, I have a bit more time to spend on these problems and they do interest me a lot.

Permalink Reply by Wiktor Kidziak on February 3, 2011 at 4:41pm

Very nice thank you! I have been playing with the definition that was described in previous posts but I don't know how to change the angle of the teeth to achieve for example the dovetail joins that you made (really clever trick). Also would you be able to show me how you orient it back to the straight strip for laser cutting?

Attachments:

zips.ghx, 171 KB

Permalink Reply by Victor Leung on February 22, 2011 at 11:34am

This is the most basic script I wrote, it is the simplest one.

Regarding the geometry being drawn, it is not super accurate. That means that there is a certain degree of variation between your Rhino dimensions and the real world bent piece. I'll later share some script about how I solve the problem.

Cheers

Victor

Attachments:

zip2.ghx, 1.2 MB
zip2_demo.3dm, 50 KB

Permalink Reply by Stephen T. Sebastian Jr. on October 24, 2014 at 11:43am

Do you have a version of this that will work on the most current version of GH for Rhino 4

Permalink Reply by Cristian Luca Atzori on November 18, 2010 at 8:06am

Your 3D bending is very interesting Victor, I hope to read news about that :)

Permalink Reply by Christoph Schindler on December 19, 2010 at 5:11am

This looks interesting!

Permalink Reply by KANAKA RAGHAVAN on June 19, 2013 at 5:48am

hey guys...we are working with non planar curves and planning to construct them with zip shape. What we are trying to figure out here in school is how to get the twist in a zip shape ...has anyone figured that out yet?I have a base file and definition that i can upload.Please do let me know,i have seen very interesting examples of work here that we have managed to translate partially .Thanks!

Attachments:

3D CURVES.3dm, 53 KB
FINAL ZIP FILE DEF.gh, 36 KB

Permalink Reply by Victor Leung on June 20, 2013 at 11:19am

Hi Kanaka,

I have previously created a definition (File won't work on current GH version anymore)

that can use the zip shape principle on a 3D non planar curve.

The principle is to look at such curve like a box beam that is bending in space. The box beam has four surface sides and four corner edges. The algorithm I took is to use a zip to represent each surface. The zip has two sides of teeth, the connecting rib is at the center of each surface, (imagine two normal zip-shape back to back). They meet with neighboring ribs at the edge, perpendicular to the neighbour.

The rest is not too complicated if you have a 5 axis mill. But without, you need further geometrical rationalization for all four ribs to be machined from flat 2.5D cut. It is do-able, I tried it on a high power laser cutter using MDF.