Mini Tensegrity Table
At first glance it seems impossible that the superhero can be supported by this table. Can you figure it out? For a bit of background on the engineering principle of 'tensegrity', head to the Blog page.
This is quite a challenging project but certainly achievable if you've got to grips with the basics of Tinkercad. MODELLING: Step 1. Drag a box to the workplane and resize it to 40mm(L) x 40mm(W) x 5mm(H) (Fig.1). This is the base. Step 2. Drag another box on top of the base and resize it to 32mm x 16mm x 3mm. Make this into a hole and centre it using the ‘Align tool’ (Fig.2). Step 3. Move the workplane to the top surface of the base. Add a box and resize it to 5mm x 5mm x 20mm. Position this box 4mm in from the edge of the base. Centre it using the align tool (Fig.3). We’ll call this part a leg. Step 4. Duplicate this leg (Ctrl + D) and position it in the same place on the opposite side of the base (4mm in from the edge). Group the two legs together (Fig.4). Step 5. Add a cylinder to the workplane. Resize it to 32mm x 32mm x5mm and increase its sides number to 48 (to give a smoother curve). Make sure you line it up with the thicker markings on the workplane (Fig.5). Step 6. Duplicate this cylinder, make it a hole and resize it to 22mm x 22mm x 6mm. Align it to the centre of the original cylinder using the align tool (Fig.6). Now group the cylinders together. Step 7. We now need to remove half of this ring shape in order to make a semi-circle arch. To do this, make a rectangular hole 16mm wide and line it up exactly with the edge of the circle (Fig.7). Step 8. Group the rectangular hole and the ring together (Fig.8). We’ll call this shape the ‘semi-circle arch’. Step 9. Rotate the semi-circle arch 90 degrees and position it on top of the two legs (Fig.9). You’ll need to use the 0.5mm snap grid to get it to line up exactly. Step 10. Move the workplane to the top of the base hole. Drag the ‘Round Roof’ shape to the workplane. Rotate it by 90 degrees and then 180 degrees so it looks like the picture (Fig.10). Step 11. Resize this round roof shape to 20mm(L) 3mm(W) 2mm (H) and centre it to the base using the align tool (Fig.11). Duplicate this shape (Ctrl + D). Step 12. Move it vertically upwards until it’s just poking through the top of the semi-circle arch (Fig 12). Step 13. Group this hole, the semi-circle arch, and the legs together to make the complete arch (Fig.13). Step 14. We now need to make the notches in the base for the elastic bands. It is very important that these notches are positioned exactly symmetrically, otherwise your table will be unstable. First move the workplane back the normal position. (Note: I’ve made my base white so you can see this step more clearly) Click on the round roof hole shape that you duplicated in Step 11 and rotate it 180 degrees. Push this right down to the workplane (Fig.14). You’ll need to use the camera controls to look underneath the base to see what you’re doing. Step 15. Align position the centre of this shape EXACTLY 5mm in from the two edges of the base corner (Fig.15a and Fig.15b). Step 16. Make three copies of this shape and place them in the same position at the other corners (Fig.16). Step 17. Rotate each of the shapes 45 degrees (two of them -45 degrees) so it looks like the picture (Fig.17). Step 18. Group these four shapes and the base plate to make them one part (Fig.18). Step 19. We now need to make the two 3mm deep square holes that the legs of the arch will fit into. To ensure a tight fit, we’ll make the holes just 0.3mm wider than the legs. Move the workplane to the top surface of the base and resize a box hole to 5.3mm x 5.3mm x 3mm. Step 20. Align this box hole to the base (Fig.20) Step 21. Setting your snap grid to 0.1mm move the box in so it’s aligned with the bottom of the leg. You can even set the snap grid to ‘off’ if you want to get it really precisely centred (Fig.21). Step 22. Set your snap grid back to 1mm. Duplicate the box hole and move across to the other leg (Fig.22). Step 23. Select both box holes AND the large rectangle hole and move them down 3mm. Step 24. Select the base as well and group them all together (Fig.24). Step 25. Move the arch and base sections away from each other (Fig.25) and do a quick check to make sure everything looks correct. Then export the two parts as separate .stl files. SLICING / PRINTING: Step 26. See Fig.26 for how I arranged the four parts of the model in Cura. I selected the ‘Brim’ build plate adhesion setting, and allowed supports. The print took around 2 hours to complete. ASSEMBLY: Step 27. You need to feed the central (yellow) elastic band around the two arches BEFORE pushing the arches into the base holes. Step 28. Place the central elastic band in the notches first, then add the corner elastic bands one at a time. Congratulations, your mini tensegrity table is complete! |
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