Umbrella Tensegrity Model

Summary Section: 

An incredible umbrella model with two umbrellas in tensegrity with each other. It features lightning bolts and even a person who lives in the umbrella. It fits within a 15x15 box and is about 23 cm tall. This was a team project made by Annieuu. It uses standard monofilament fishing line, but any other line will work. The hooks were bought from: https://www.amazon.com/gp/product/B07JMK9GCC/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Lesson Plan and Activity:

We had to create a custom tensegrity structure with a partner. It had have similar complexity to these:

Parts List: 

• Aeo_2.0_TopUmbrella.3MF *1
• Aeo_2.0_BottomUmbrella.3MF *1
• Aeo_2.0_Person.3MF *1
• Aeo-2.0_Lightning Bolt.3MF *2
• Aeo_3.0_Handle.3MF *2
• Fishing Line - more than 12 cm pieces e(xtra room for knots)  *3
• Hooks (any hook with a screw-like base will work)  *8
  • Link to purchase in the summary section
• Rulers (for measuring the string)

Assembly Instructions: 

1. Print out all the parts and gather the materials you need.

2. Insert the hook into the hook holes.

1. Take the hook and place it into the hole. Begin screwing in the hook. 
2. If the hole seems to small, use a small screwdriver or other sharp tool to make it bigger (be aware that it might break if pushed to hard)
3. If the hole is too big, take a hot glue gun. Stick screw part of the handle into the tip of the hot glue gun. Press the button on the hot glue gun and coat the hook in hot glue
4. Now that the hook will fit. Continue screwing in the hook until it is completely in the hole
5. Be careful, if you screw the hook in too far in the handle the handle might split. We had this issue many times and broke a few hooks.It should not look like thisIt should look like this
6. Use flush cutters to cut a hole in one of the handle hooks.

3. Push the handles into the connectors on each umbrella. Some sanding might be required depending on the 3D printer. The handle should be facing in. The handle goes out but then curves back in so the top is centered.

4. Now use the fishing line to connect the umbrella part —Start off with loose square knots or single knots on the hooks. (Or any other knot that can be untied easily)

1. How To Tie A Square Knot (Step-By-Step Tutorial)
2. 

(The hook is not in the umbrella to get a better angle and we took the video after assembling the umbrella fully)

5. Three strings should be added to the outside. Each string should be 12 cm with extra room for the knots.

6. Tie each fishing line to its two corresponding hooks.

7. If the umbrella does not ‘float’ or is unbalanced, untie and adjust some of the strings to be different lengths. 

8. The umbrella should look balanced like this:

9. Tie another knot to make sure it stays and you can now push the lightning bolts into their holders and the person into its slot, some hot glue may be required

10. After the umbrella is level, pull on the excess string to make sure the knots are tight. Cut off the excess string. It’s done!

Design Choices: Leo

When first thinking of ideas, we had trouble. A bird, triangles, half-circles, and hands were our only ideas after a full class of brainstorming. Then we had the idea for an umbrella and a hand, which was modified into two umbrellas.

• When first sketching out our model, we planned to have arcs around the side of the hexagon so it would not really be shaped like a hexagon. However while making the model in solidworks we decided to add arcs (r3) connecting the tips of the two hexagons and use those as guide curves to make a shape that looks more like an umbrella.

• Originally we were planning on angling the whole design to make it more interesting and so the handles would connect better using an extruded cut on an angled square, however we changed it to be flat for better stability.

Original Plan:

• Originally, for the connecting handle part we were planning on making an angle in the handle, but while modeling it in solidworks, we decided it would be better and more efficient to angle the handle connecting point and have a straight handle. The handle connecting point would be extruded along a line at a 101 degree angle.

Our original design:                                      Our final design:

• Instead of having a rim around the inside of the umbrella, we decided to only have three extruded bases for hooks to connect to.

• In version 1 we drilled holes in the umbrella and handle to make the hole for the screw. However this was unreliable, so we made holes in solidworks to put the screw in and used a screwdriver to make the hole a little bigger. The hole had a dimension of 0.11cma and was 0.630cm deep. The reason we switched was because when drilling into the handles, they would split and the screw would not stay in the hole. One handle completely split into two different pieces!

• Instead of having the base of the umbrella be flat we added arcs to create a more umbrella-like shape. We used an arc with a radius of 15 and an extruded cut.

• In version 1.0 we had the hole where the handle connect had a diameter of 0.83cm but we had to sand the handle a lot which made it unaligned. In version 2.0 we made the diameter bigger to be 0.84cm and the handle fit better. Also we moved the connecting point off center so it was no longer in the middle of the umbrella so the handles fit together better. It was 0.75cm off the center.

• In version 1.0, we had a string connecting the two handles, but in version 2.0 he had hook to hook connection. We took flush cutters and cut the top hook.

From this ^ To this ^

• We add designs: a person standing on the bottom of the umbrella and two lighting coming down from the top umbrella.

• Originally we were going to make a small notch in the side of the umbrella, but we were advised it would be too weak, so we changed it to connect similarly to the hooks.

Construction Instructions: 

Umbrella Handle (Print x2)

1. First make a circle with a diameter of 0.8cm on the origin on the top plane. Draw a horizontal construction line diameter through the origin.

2. Add a horizontal line at the top of the circle that is 0.3cm away from the construction line just drawn.

3. Mirror that line across the diameter just drawn in step one

4. Use the trim entities tool to cut the sides of the circle away:

5. On the front plane draw a line that is 11 centimeters tall from the origin. Then add an arc that has a diameter of 1.5cm and is 0.75 cm tall.

6. Sweep the circle drawn first along the line and arc.

7. Then filet the end of the arc with a 0.3cm filet on each side

8. Next create a new plane along the tip of the umbrella:

9. The plane should have a first reference point along that centered line, and the second reference should be the perpendicular side face, set to a perpendicular reference:

10. Next draw a circle with a diameter of 0.11cm on the center of the centered line that was the first reference. 

11. Next, exit the sketch and use an extruded cut to cut the place for the screw. You should extrude cut it 0.63cm

12. Click the check mark, save as an STL or .3mf and print it!
 

Umbrella Base (Print x2)

1. In the top plane draw a hexagon with a diameter of 15cm

2. Create a new place 6 centimeters above the top plane

3. Draw another hexagon with a diameter of 6cm above it

4. Add a new axis from the center of one hexagon to the center of the other hexagon

5. Create planes along that axis. Each plane should align with a point on the hexagon. 6 planes total should be added

6. One each of those 6 planes, draw an arc with a radius of 60 degrees. The arcs should each go from one point on the hexagon to the corresponding point

7. Use the loft tool. Select the two hexagons as the two profiles and in the guide curve section, select each arc created.

8. It should look like this:

9. Next create the part where the handle will connect.Create a new plane 5.5 cm away from the top plane. On that plane create two circles. The smaller circle should have a diameter of 0.3cm and the larger circle should have a diameter of 1.8cm.

10. Draw a horizontal construction line diameter for the smaller circle

11. Add a horizontal line 0.32 cm away from the diameter line that goes from one edge of the circle to the other edge of the circle.

12. Mirror that line over the horizontal line.

13. Use the trim entities tool to cut away from the circle.

14. It should look like this: 

15. Next, on the front plane create a line that is 1.5cm long. The line should be at an angle of 101 degrees from the edge of the umbrella body

16. Next sweep the two circles along the created line

17. Then filet the line connecting to the base with a radius of 1cm

18. Then filet the top part of the shape with a radius of 0.5cm

19. The final connector should look like this:

20. Next make the parts where the three outside strings connect

21. First create an arc near one of the corners. The arc should have a radius of 5 degrees and each endpoint should be 2cm away from the vertex of the corner:

22. Next create two construction lines that are diameters for the umbrella. The first should start in the corner the arc above was made around and the other should start from the corner next to that one. Each line should travel to the opposite corner:

23. Next mirror the created arc around the two construction lines so there is an arc in three of the 6 corners in every other corner:

24. Now use a boss extrude offset down one centimeter from the top and select up to next. If necessary, change the direction of the extrude so it goes down into the umbrella:

25. In order to make a hole for the hooks, create a new plane referencing the extrude surface that was just made. Draw a construction line from side to side like the following, and draw a center circle of the diameter of 0.11 cm in the midpoint of the construction line.

26. Mirror the circle (draw construction line if necessary) to each side to the 3 corners. Extrude cut 0.63 cm deep.

To make the person:

1. On the _ plane, create a sketch of a figure in the umbrella (the figure can be any shape as long as it doesn’t extend beyond the handle’s connecting hole.)

To create the place for the figure to fit, offset __ to create a slightly bigger box and extrudeTo make the part where the lightning bolt connects

1. open the top umbrella and create a new plane with the part where the hooks attach as the reference.
2. Create an arc roughly in the middle with a radius of around 1.4cm add a line connecting the two sides of the arc
3.  Create a center construction line and mirror the arc to the opposite side of the umbrella;
4. Use a boss extrude. In direction one, select “Up To Next”. In the “From” box, select offset and offset it 1cm down:
5. On the newly created platform sketch a box in the middle. The box should be 0.84cm long and 0.2cm wide:

6. Use a “Cut Extrude” and extrude it 1cm down:

7. Fillet all the edge of the box with a fillet with a radius of 0.25cm

Lightening Bolt:

1. To make the lightning bolt, draw a lightning bolt as best you can, at the base, it should be 0.8cm wide. The whole lightning bolt should be 5 cm tall:
2. Next, extrude the lightning bolt 0.16cm up:
3. Now, in a new sketch draw a square on the lightning bolt. It should have a side length of 0.93cm:

4. Now extrude the square 0.16cm up so it is level with the rest of the lightning bolt: