Untitled Airless Basketball

Untitled Airless Basketball v0.3

An airless basketball for the people, designed with Kimya PEBA-S filament

v0.3 - This version corrects the overall ball thickness to 9mm, right about where I expect I need it for ideal bounce. It also changes the inter-lattice structure to evenly distribute the holes on all hexagon sides,. Both of these changes together should further increase lattice rigidity. I'm also including a .3mf project file so you can get an early look at the settings needed to print this material well. Spoiler: it's really difficult and takes over 5 days.

Support Instructions:
I use Orcaslicer, but you should be able to follow these for Bambuslicer too. Click on your model to highlight it, then press Ctrl+1 to switch your camera view to the top of the model. Now we select Support Painting, set tool type to “Fill”. From our top down view, adjust the section view between .65 and .70 (I'm still walking this in myself, 65 is ultra-conservative and costs more material, .7 provides less support and is riskier). Now, hit Ctrl+2 to switch to bottom view. From here, you can select model faces from only the horizontal model section created by your section view. Left click the outer face of each rib and hexagon cell within the visible model area to highlight it for support generation. Avoid highlighting geometry inside the lattice, this will make support removal harder and negatively affect the ball's integrity.

6/19 Update: v0.2 is suuuuuuper scuffed. Not even launching next version until I have a successful print. This stuff has the overhang performance of molasses. 

v0.2 - Ribs still incomplete but closer to final form. Incorporates my new approach to overhang optimization by solidifying the vertical walls of each hexagonal cell. I've highlighted these solid walls in blue on my included close-up screenshot. Normally I advise people to print from .step files, but this file will crush your system memory and I strongly suggest printing from .stl 


The double hexagonal lattice of Wilson's SLS printed Airless Gen 1 presents several issues for FDM printers. Flexible filaments have inherently poor bridging and overhang performance, and the orientation of the ball's hexagons affects the printability of the lattice. Untitled Airless Basketball aligns its hexagonal cells “pointing” vertically along an FDM printer's Z axis to minimize bridging and overhangs in excess of 45 degrees. I am actively working to prove that these optimizations combined with Kimya's 93A shore hardness PEBA-S filament can produce a ball capable of meeting the following NCAA standards:
 

1. Under 22 ounces (623.69grams)
2. Diameter between 9.39 and 9.55 inches (238.5mm - 239.52mm)
3. Composition such that, “when it is dropped onto the playing floor from a height of approximately 1,800 mm measured from the bottom of the ball, it will rebound to a height of between 1,200 mm and 1,400 mm, measured to the top of the ball."

Notes for further reading:
Shore hardness alone is an insufficient metric for evaluating a filament's suitability for printing sportsballs. I have found a number of other promising filaments which exhibit high energy return and warrant further testing. 
 

• Ninjatek's 83A Edge 
• Filamentum's 90A PEBA-S

Goldberg Polyhedra