Floating Umbrella (Tensegrity Model)

prusaprinters

Summary Section (cont.): Isolated objects held in position by continuous tension and compression, this floating compression is known as tensegrity. This Umbrella Tensegrity Model was a team project made with Leos. Print them out to see how it works!The hooks that were used in this model: Link. The line are standard monofilament fishing line considering its transparency and strength.  Lesson Plan and Activity:We had to create a custom tensegrity structure with a partner. The model should fit in a 15cm x 15cm x 20cm box with similar complexity like the following images:Parts List: 3D Printing :Aeo_2.0_TopUmbrella.3MF*1Aeo_2.0_BottomUmbrella.3MF *1Aeo_2.0_Person.3MF *1Aeo-2.0_Lightning Bolt.3MF *2Aeo_3.0_Handle.3MF *2Assembly :Fishing Line *3 - more than 12 cm per pieces (extra room needed for knots) Hooks *8 (link or any hook with a screw-like base will work)Rulers if needed (for measuring the string)Assembly Instructions: 1. Print out all the parts and gather the materials you need2. Insert the hooks on the tip of the handle and the umbrella extruded part.Take the hook and place it into the hole. Begin screwing in the hook. 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)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 glueWhen screwing the handle part, be careful that if you screw the hook too far in it might split. We had this issue many times and broke a few hooks.The handle part with a hook:Use flush cutters to cut a hole in one of the handle hooks. The umbrella part with 3 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)How To Tie A Square Knot (Step-By-Step Tutorial)( The hook is not in the umbrella to get a better angle ^ )Three 12cm+ strings should be added to the outside. Tie each fishing line to its two corresponding hooks. 5. If the umbrella does not ‘float’ or is unbalanced, untie and adjust some of the strings to be different lengths. 6. The umbrella should look balanced like this:7. 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 required8. 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:As a group, we brainstormed the design of the tensegrity model. We came out with a few designs that are creative and could apply tensegrity. The design chosen at the end are two upside umbrellas that can be connected with the handle.There are the following design change we made along the way:Originally, we planned to have arcs on the sides of the Hexagon shape. However, we notice the umbrella panel edges(from the top view) wouldn’t have arcs but instead the panel curve. We add arcs (r3) connecting the tips of the top and bottom hexagon correspondingly and loft with the arc to get the curving of the umbrella.We decided not to cut out the bottom to angle the whole umbrella structure considering that the umbrella needs to line up and balance. (originally planned to create a new angled surface with cut extrude)For the connection part, we didn’t make an angled half way handle like we originally planned, instead, we angled the connection base of the handle. We make the base swept upon a 101 degree line (handle angle is toward the inner part of the umbrella):Our original design(left) and final design(right): The inner connections - instead of all around the umbrella shape. We only made 3 excluded flat to hold the hookOriginally we planned on drilling holes into the model to add screws. While assembling, we noticed it was inconvenient to drill holes and the hooks could easily split the handle apart. After we notice the issue, we decide to "pre-hole" in SolidWorks. The diameter of these holes are 0.11cm with the depth 0.63cm, tested with the hook used. To make the umbrella more realistic, we add details for the umbrella edges by drawing an arc with a radius of 15 on the edges and extrude cut all the way for each side.The connection bases are moved 0.75 away from the base so the handles wouldn’t be touching each other and increase the inner circle of the handle connecting part to a radius of 0.84 to create a looser fit compared to version 1.0.Originally we were planning on using a string in between the hooks, however in version 2.0 we changed that to have hook to hook connection. In order to do this, we took flush cutters and cut a hole in one of the hooks.Designs we add at version 2.0: a person standing on the bottom of the umbrella and two lighting coming down from the top umbrella.When making the connection part for the lightning bolt, we originally planned to make a small grove on the side of the umbrella. However, considering that it would be too weak and thin when printed, we add a similar connection platform as the hooks. Construction Instructions: Umbrella Handle (Print x2)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.Add a horizontal line at the top of the circle that is 0.3cm away from the construction line just drawn.Mirror that line across the diameter just drawn in step oneUse the trim entities tool to cut the sides of the circle away: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.Sweep the circle drawn first along the line and arc. Then filet the end of the arc with a 0.3cm filet on each sideNext create a new plane along the tip of the umbrella: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:Draw a circle with a diameter of 0.11cm on the center of the centered line that was the first reference. Exit the sketch and use an extruded cut to cut the place for the screw. You should extrude cut it 0.63cmClick the check mark, and the handle is done. Save as an STL and print it!Umbrella Base (Bottom and Top)In the top plane draw a hexagon with a diameter of 15cmCreate a new plane 6 centimeters above the top plane(also centered in the origin)Draw another hexagon with a diameter of 6cm above itAdd a new axis from the center of one hexagon to the center of the other hexagonCreate planes along that axis. Each plane should align with a point on the hexagon. 6 planes total should be addedOne 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 pointUse the loft tool. Select the two hexagons as the two profiles and in the guide curve section, select each arc created.It should look like this: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 0.84 cm and the larger circle should have a diameter of 1.8cm. Draw a horizontal construction line diameter for the smaller circleAdd 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.Mirror that line over the horizontal line.Use the trim entities tool to cut away from the circle.It should look like this: 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 bodyNext sweep the two circles along the created lineThen filet the line connecting to the base with a radius of 1cmThen filet the top part of the shape with a radius of 0.5cmThe final connector should look like this:Next make the parts where the three outside strings connectFirst 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: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: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: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:In order to make holes 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 at the midpoint of the construction line. Mirror the circle using the same method from step 22 and 23 (draw construction line and mirror the hole to all 3 corners). Exit the sketch and cut-extrude the sketch with circles 0.63 cm deep. Now the basics for the umbrella is done, it’s time to copy this file and turn them into Top Umbrella and Bottom Umbrella.Select the Right Plane to sketch the design. Use section View to get a better view of the inside.Sketch the person (or your own design). Make sure the feet of the person goes into the umbrella and the other side doesn’t hit the umbrella or place for the handle.On a new sketch, cut the bottom part that goes into the umbrella and delete the top part only leaving the bottom square. Offset the square 0.03 cm to create a slightly bigger boxCut-extrude the offset square in both directions, 0.02 cm and 0.27 cm, for the 3 dimensional cut to hold the person’s leg.Filet the following selected lines with radius of 0.1 cm.Back to the original person's sketch, copy the sketch and paste it on a New Part.On a vertical plane to the person sketch, create a line from the person and extend out 0.25 cm. Swept the person along with the 0.25 cm line.To make the part where the lightning bolt connects, open the top umbrella and create a new plane with the part where the hooks attach as the reference. Create an arc roughly in the middle with a radius of around 1.4cm add a line connecting the two sides of the arc Create a center construction line and mirror the arc to the opposite side of the umbrella;Use a boss extrude. In direction one, select “Up To Next”. In the “From” box, select offset and offset it 1cm down: On the newly created platform sketch a box in the middle. The box should be 0.84cm long and 0.2cm wide:Use a “Cut Extrude” and extrude it 1cm down:Fillet all the edge of the box with a fillet with a radius of 0.25cmTo make the lightning bolt, open a New Part and draw a lightning bolt the best you can. It should have 0.8cm wide base. The whole lightning bolt should be 5 cm tall:Next, extrude the lightning bolt 0.16cm up:Now, in a new sketch draw a square on the lightning bolt for the connecting lock. It should have a side length of 0.93cm:Now extrude the square 0.16cm up so it is level with the rest of the lightning bolt: