100806_zip_curvature_adjustment_s

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Comment by machinehistories on August 13, 2010 at 1:02pm

Christoph thanks for the comments and I am Jason. Yeah, I like the idea of doing some of this research as a correspondence. In terms of the shape it doesn't really matter to me, it's more a matter of using the Zipshape method on a developable loft. If you want to create a loft and output it's Zipshape, I can then machine it out and see what we get. We could do something that's maybe around 2sq ft and then maybe we can try a few different materials and sheet thicknesses. Maybe we find an application for the shape instead of just doing a proof of concept. What do you think we should design - maybe a magazine or newspaper rack. This could be fun.

Comment by Christoph Schindler on August 12, 2010 at 9:45pm

Dear machinehistories (so, are you Steven or Jason?),
I would say that it should be possible to fabricate such a shape with Zipshape, depends largely on the size of it, desired thickness of the panel, radii and such. If you want, you could send me that surface—and thickness—and I return to you the developed panels.
Your work at machinehistories looks great. That would be my dream, to have a workshop and be my own manufacturer. However, you name it, my «work simultaneously straddles several disciplines» and I would find myself unable to decide on a certain machinery…
Best, Christoph

Comment by machinehistories on August 12, 2010 at 12:46pm

Christoph,
I teach full time at the Art Center College of Design in Pasadena and I also have a company - machinehistories - www.machinehistories.com which does a variety of different types of projects but for the most part we make one-off's and furniture mainly. I completely understand not being around the corner but I am just putting it out there so that next time to come out to Los Angeles you might set aside a few days and we can further explore some of these possibilities. I feel that reproducing a ruled surface would be amazing. I am attaching an image of the ruled surface and it's flat pattern with bend lines based on a .05" deviation. I am not sure, just a hunch really, but I feel like this might provide a good map on how to recreate the surface using your technique.

Comment by Christoph Schindler on August 11, 2010 at 9:54pm

Wow, that is a comment!
As you assume, Zipshape is fabricated with 5-axis sawing, you can see this here http://www.schindlersalmeron.com/index.php?option=com_content&t.... However, I currently do the testing on a 3-axis machine at ETH. Takes quite a while, but has the great advantage of running the machine myself.
Both angle and distance are changed. But what makes it quite complicated is the material behavior—because of the teeth, the bending is not smooth, but rather behaves like a polyline that only looks smooth on the outside because of the elasticity of the material.
Thanks for your software hints, I will try to have a look at them.
Using your workshop sounds really tempting as I do not have one, although it is not around the corner. Are you professional or academic (or even both)?

Comment by machinehistories on August 11, 2010 at 12:41pm

Alvar Aalto did some interesting things with splines that isn't totally unrelated and can be found in the book Bent Ply. i recall seeing your process in From Control to Design and thought it was a very interesting and smart way to construct surface. I tried some experiments out using a similar idea - take a developable surface which has a series of holes cut through it now offset that surface and unroll both of them, once both have been cut out insert a dowel into the holes (the dowel represents the offset distance). In the end the shape is recreated via tension and in that way there are some similarities. With your concept the thing I have trouble figuring out is how do you cut the variable angle kerfs. Are you using a 5-axis swarf cut, a cnc panel saw - how do you control this? It would be great to have a set of constraints which limit the number of possible angled cuts - these limits would equal the number of v-groove bits you have in the cnc - and then you could just cut the lines with the programmed tool which matches the given angle. Or maybe I am completely wrong, now I think I am wrong, about the execution and you are only changing the gap between each kerf and the angle of the side wall stays constant.
Anyway to answer your question catia can analyze the characteristics of a piece of formed material (this analysis is usually applied to sheet metal and to design forming tools)it's just a matter or defining the material to match that which you are using. Another possibility although not as numerically clear is using a simulation tool like Maya cloth or Virtools. I know this maybe less likely but you can define all sorts of materials in Maya and then simulate their behavior under numerous forces and constraints. I think it would work it's just how do you extrapolate the values Maya needs and then correlate them back into the cloth parameters. Once it yields the final formed mesh then further analysis could be performed in cosmos, ansys, or catia.
I have one other suggestion. In solidworks if you perform a lofted bend on a sheet metal part and then generate a flat pattern it creates a large set of bend lines representing how to perform the bending of an unusual shape using a metal brake. It seems like those bend lines could be machined with you technique to create lofted forms instead of extrusions.
What materials seem to work best so far, have you only been using wood (the purple stuff is probably not wood)?
If you are ever in Los Angeles I have a shop with a 3 axis and 5 axis router, a large vacuum bag, and all the other things to experiment on this and would be open to this.