More Plastic Parts for ConstructionPosted: October 12, 2011
After creating the first quad connector, I thought about how I could improve upon the design.
The design is pretty straight forward. I want to support some slats of corrugated plastic panel that are arranged in a torsion box fashion. That just means the pieces interlock with each other with notches cut into them to accomodate the overlap. The support piece simply has slots within which the slats can slide and be supported. For the base of the connector, I didn’t want to simply make it square, because I don’t think that is the optimal shape for saving on plastic. So, in the first design, I reduced the amount of plastic by cutting out the corners with a cylinder.
This design works well enough. As you can specify the length and depth of the supporting walls, it’s fairly straightforward to specify exactly how much support you want out of the piece.
There are two sides to a circle though. I decided to try it the other way, by making the connector base circular.
This one has the advantage that it does not have the sharp edges on the base like the previous one does. It still has sharp edges on the supports though. I think this one is more aesthetically pleasing, and easier to “understand”. It’s just a round cap that goes over some joined pieces of material.
As this is as much a study in how to use OpenScad as it is about creating an actually useable piece, the OpenScad code has been updated in the github library.
One of the nice things about OpenScad, since it is a text based modeling program, is that you can easily change some parameters and generate a different result. In this particular case, the primary routine is called ‘connector()’. The full list of parameters is as follows:
connector(length, thickness, height, gap, corners, hole, style)
This last parameter determines the style of the connector. It can be either ‘CIRCULAR’ or ‘CUTOUT’. The default style is ‘CIRCULAR’.
Just to pull it altogether, I created a more complete image of the torsion box.
This shows a more completely, if fairly minimal, torsion box, with circular connectors installed on all of the vertices. The torsion box can be of any size, and utilize any appropriate material. My original intent was to use the corrugated plastic panel. As I have not as yet tried, I don’t really know how well it will work. I tend to think the connectors will actually face down to the ground, leaving a totally flat surface on the top to support flat flooring panels.
The code found in connector.scad is fairly straightforward, with an emphasis on modularity. I could have coded this up in a single routine, but instead I broke it down into constituent parts so the design could be easily modified, altered, and improved. If you’re into studying OpenScad code, this might be a good one to look at for a simple object.