tensegrity shell

Tensegrity is a structural principle where elements under compression do not touch each other. They're only connected and hold in place by tensioned (usually cables). The term "tensegrity" is short for "tensional integrity and was proposed by Buckminster Fuller in the 1960s.

This model of a tensegrity shell is an experiment/extension of the tensegrity arc. Simply put, it is a concatenation of arcs with a modified t to get a smoother transition. There's no assembly required, the whole model is printed in a single process without the need of material. The focus here is on FFF/FDM as fabrication method. The larger elements are only connected through fine strands to each other for stabilization. It's just filament extruded into the air. This technique is called bridging.

The model is rotated by 90 degrees when printing, so the strands are always parallel to the printing surface. The length of the shell is only limited by the available height of the build space. The dimensions of the shell in the picture are ~22 x 13 x 35cm.

Geometry was created using Rhino/Grasshopper.

Printer: Generic

Rafts: No

s: No

Resolution: 0.2 mm

Infill: 20

Filament material: PLA, PETG

Notes:

This model has an experimental character to it and might be difficult to print for unexperienced s (especially the bridging). You can try out one of my free models with the same technique before purchasing this one.

The height (=length of the shell) is 40cm. You can print a smaller section of it at any height by adjusting your slicer settings, so it will match your available build volume.

The model is stable but somewhat fragile, so handle with care during the process.

Note: There's a 3mf-file included with a complete setup ready to print.

The model is split into two files:

1 - connecting elements

2 - strands

The orientation of the geometry is as it is laid out in the stl files.

You have to combine them first in your slicer-software (PrusaSlicer or Cura recommended). You can go for a multicolor print if you wish to, but the separation has one advantage in general (even if you're doing only one color). For better explanation have a look at the included picture of the slicing process:

If you're just combining the models and the settings for each model are identical, the extrusion of the strands will end at the perimeter of the elements (A). However, if you change e.g. the number of perimeters for model hashtag 2, it will reach into the elements beyond the perimeter. This also results in a continous extrusion and leads to a better connection (B). This behaviour was tested in PrusaSlicer 2.3.0, it might be different for your slicer software.

s are not necessary. If you wish to, you can still turn on s. Bare in mind that removing s on this model might be near to impossible without breaking it. Soluble s might be the better option here.

Activating "thin walls" will help with the detection of the strands.

Clean you print surface and ensure good adhesion. Brims are recommended.