Tensegrity christmas tree

Tensegrity christmas tree.

Wishing everyone and their families a wonderful christmas time and all the best for 2022!

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

This model is a variation of some recent experiments with printing scripted tensegrity structures. There's no assembly required, the whole model is printed in a single process. 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 dimensions of the tree in the picture is about ~8x8x15 cm.

Geometry was created using Rhino/Grasshopper.

Printed with Spidermaker Filament Matte PLA (Iron Blue, Dark Slate Green, Wasabi Green) on a Prusa i3 MK3S (layer height 0.2 mm).

Printer: Generic

Rafts: No

Supports: No

Resolution: 0.2 mm

Infill: 20

Filament material: Spidermaker Filament Matte PLA (Iron Blue, Dark Slate Green, Wasabi Green)

Notes:

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

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

Note: There are two 3MF-files included (PrusaSlicer and Cura) 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 Nr. 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.

Supports are necessary, because the upper parts of the tree all have a different width. However, automatic supports are not recommended, because the slicer will put it everywhere. Bare in mind that removing supports on this model might be near to impossible without breaking it. Soluble supports might be the better option here.

Prusaslicer:

There are already paint-on-supports included in the 3MF file.

Cura:

Install a plugin called "custom supports" first. Supports are also already placed correctly in the corresponding 3MF file.

If these options do not work for you, there's a STL included which can be used as support enforcers manually.

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

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