Week 5: Modular Press Fit Kits

This week we focused on a range of press fit joints and modular design. Below I have included prints of the press fit and ball joint examples, as well as my own modular interlocking design.

• Rhino
• Grasshopper
• Cura
• Illustrator
• Fluorescent PLA
• Marble PLA

I began by using the initial code examples to test basic press fit joints. On the initial press fit, I messed up the parameters, so four of the male parts were way too small for the female part, and the one that fit was way too tight. It fits, but needs a greater tolerance to come off easily. It also only fits in one orientation, rather than fitting universally. I noticed that my initial layers expanded (perhaps too much pressure before I re-leveled the bed), which made the connection even tighter. I cleaned these layers up a bit with sandpaper, which helped the fit.

Next, I tried the simple ball joint example. My initial ball from the example file was too small, so I incrementally scaled up three times to find a ball and socket combination that worked. There was still more room to scale up the ball, which I did on the hexagonal joint.

I also finally got around to printing calibration cubes in all of my filament options. This will help when deciding which filament to print with in different circumstances. It also helped to dial in different nozzle temperatures.

Originally, I (naively) envisioned printing enough hexagonal and pentagonal hubs to make a half or full geodesic dome, but I ran out of print time to produce enough parts. My idea was to print the hub socket joints, ball connectors, and to span the distances with store-bought wooden skewers. I had to print couplers to attach the skewers to the ball joint.

Upon realizing the mathematical impossibility of printing enough parts, I shifted my goal to making one hexagonal iteration this week, which could theoretically get scaled up to a full hexagonal dome. I have made multiple inflatable geodesic domes over the years, so I understand the basic geometry, but would need a lot more production time than I had this week. My kit didn't fully work out in time to start constructing models, but I included all the parts I was able to print in time.

The first coupler I made didn't quite fit, and I need to do a few scaling tests to get it to fit properly on the ball joint shaft and the skewer. I attempted to keep printing these, but my prints kept failing to adhere to the bed, and it got too late to continue. I adjusted the flow rate and the temperature, but the extruded PLA kept coiling instead of adhering properly to the bed, and the prints kept failing. I realized a little too late that the ball end fit pretty perfectly on the skewer without a printed shaft, but my prints kept failing before I could do just a ball end test. Printing these ball ends and adhering them directly to the skewers would save a lot of print time.

The final image is of a full scale inflatable geodesic dome I made many years ago.

I have been using the command symbol in my artwork, and while working on this assignment I wondered if I could make a modular interlocking design from this symmetrical symbol. I began with a vector illustration, which I extruded in Rhino. I attempted to slice the junction points of the curves with a Boolean Difference in Rhino, but after some frustration, I opted to make these breaks manually with my diagonal cutters. I cut one point where the curve meets the central square radially on each loop. This break allows each loop to snap into each other to build modular forms. I was pleased with how reality lined up with my theory, that the memory of the printed curve would snap the form back into shape. This extrusion was thick enough that the loops are pliable, but snap back into shape well. Some of the pieces warped over time, so I might want to thicken it up a little bit. I'm curious how the flexibility of this system will hold up over time. Ultimately, I think it was a productive test, and a good realization of my idea. I worried that my design didn't fully fit the press fit parameter of the assignment, so I continued to work on a hexagonal hub ball joint system.

I was directly thinking about Tauba Auerbach's exhibition S v Z at SFMoMA, which closed this weekend, and I was disappointed I didn't find the time to go see it. These forms are subliminally and directly inspired by that work.

The above images are as follows:

1. Single command module
2. Two linked command modules
3. An array of command modules showing complexity through iteration
4. Detail
5. Four interlinked command modules, showing added complexity on the z-axis
6. Eight interlinked command modules, showing added complexity and interrelation of parts
7. Four interlinked command modules in a square formation
8. Rotated 90 degrees in a diamond formation
9. Five interlinked command modules in a pentagonal formation
10. Six interlinked command modules in a hexagonal formation
11. Rotated
12. Six interlinked command modules emphasizing a central triangular intersection
13. Same formation flipped over 180 degrees
14. Arrangement #6 dangled with gravity
15. Arrangement #6 dangled with gravity
16. Stack of modules
17. Array printed from Cura slicer
18. Single test module on print bed (I had some bed adhesion problems this week, and had to re-level the bed)