Nazmul Azim Khan is a second-year student in the Computational Design program at the University of New South Wales. While taking a digital fabrication course he was assigned a project to conceptualize a paneled facade made out of clear acrylic plastic to be held together by a spider jointing system.
A spider jointing system is exactly what you would imagine it would be (unless you had conjured up images of smoking arachnids…) — a multi-legged raised bracket that bolts to panes of glass at their juncture as an external structural system. The particular spiders used for joining in this project would raise naturalists’ eyebrows as they appear to have at least 15 legs, but in the world of 3D printing, they fit right in.
Khan used Rhino3D in combination with Grasshopper to create the scripts. As Grasshopper is a visual scripting language, it allows the user to ‘draw’ the output while the program creates the scripting. So, in other words, he worked with rhinos and grasshoppers to make spiders! Rather than being as chaotic as that menagerie sounds, the most complex part of the project was actually in the design itself.
“The most difficult part of the design process was trying to resolve how the spider joints would connect to the panels,” Khan explained. “I wanted to create the simplest connection and avoid exposing any nuts and bolts. This was resolved through the use of screws and wall-plugs. The wall-plugs have been inserted into a hollow section of the 3D printed spider joints, which prevents any exposure. This allows the screws to simply screw in from above.”
The facade as currently designed is 10 x 10 meters; however, because of the parametric nature of its design, it can easily be adjusted to fit any space. If the inputs regarding the size or curvature of the panels being held together are adjusted, the spider joints will be instantly adapted in the model as well. The only parts in the assembly that aren’t 3D printed are the screws. Khan justifies that compromise because of the time to print those readily available pieces and turns it into an interesting statement on the juxtaposition between mass-customized products and mass-produced elements.
The Computational Design Society, of which Khan is the president, has taken this project on as its next challenge. Moving from digital model to full scale installation will be the ultimate test of the design.
“At the moment, only a few joints have been printed out for testing and display. The ultimate plan is to create an entire paneled facade to display as an architectural installation. We have currently been given an exhibition space. Over the next month or so we plan to change the size and shape of the paneled facade to suit the exhibition space. This requires measuring the space and then making minor edits to the script which generates the spider joints,” he said.
Working with digital models, Khan was able to quickly evaluate his design decisions for both the joints and the truss system holding them in place.
“A decision was made to structurally reinforce the spider joints with a truss system,” Khan noted. “The trusses are influenced by complex bridges such as the Sydney Harbor Bridge. The original design appeared to be very rectilinear and boxy. By introducing curved lines and a rotating truss system, the form instantly became more dynamic and interesting. They explore a unique balance of structural and fluid forms.”
The ability to easily generate the physical models has given the team working on the project confidence that the final installation will be a success. Khan described the role that 3D printing the prototypes played in their decision to undertake the larger installation:
“Overall, the spider joints performed successfully and as intended. This was a relief as there was a high chance of failure because everything needed to work within a 1mm tolerance. This left no room for inaccuracies and errors in the script that generated the spider joints. To ensure that there were no miscalculations, several draft models were printed and tested to see if the panels attached correctly and were strong enough. All of the draft models worked successfully and so the final model was printed with confidence.”
Having successfully completed this project, Khan has started a blog to document all of his experimentation both in 3D printing and in other fabrication techniques and we look forward to watching his continued contributions to design and creation! Discuss this innovative experimentation in the 3D Printed Spider Joints forum thread over at 3DPB.com.