Introduction: Arcrylic Geodesic Dome With LDR Lighting System

About: Currently and engineering student with a design flare.
Geodesic Dome - Intro
Is one of the strongest structures in the world.
Invented by an American man called R.Buckminister Fuller.
It is defined as the lightest, strongest and most cost-effective structure ever devised. It is formed by a network of triangles to form a roughly spherical surface. A triangle is the strongest geometric shape. A sphere is defined as the geometric shape that encloses the most volume, with the least amount of surface area.
Forty feet of wall will enclose a 10x10 area 100 square feet of wall will enclose 127 square feet which is a 27% increase.

The unique curved shape makes the dome aerodynamic which can withstand gale force winds and its low centre of gravity prevents earthquakes from severally damaging the structure. All together geodesic domes offer the safest shelter in the most violent weather extremes around the world.
Youth contest answer paragraph,
I got the idea when I was looking for a structure that is lightweight, strong, durable, looks great and is cost efficient. Without doubt this project ticks every box and I'm hoping to make a real life structure based on my model.....Someday. I made it at home and in school. I done most electronics and fiddly things at home while doing all basic parts of the project at school using the CNC router to assist me. e.g; the triangles and base. My lighting system changed halfway so it did not interfere with anything. I changed from spotlights to ground lights. Thought it would look better. Can't complain about the decision. My biggest surprise was when the cap of the real project fit in perfectly because even the smallest mis-calculation can affect the result. I couldn't believe it worked out :P. My proudest moment was when I got to peel away the masking tape and uncover the beautiful clear structure. It is very strong when it is all glued. I could push down on it with my hands with a lot of pressure without anything budging. I didn't want to do anything else do...just in case :P.

Step 1: Research

The Geodesic Dome;

The geodesic dome is one of the most adaptable structures as it can adapt to all weather terrains. It is found in many parts of the world serving different purposes.

Some areas of the project required expert information as I did not know the answers to the desired information. The following pages are based on the communication skills I had with other people to fulfil my project correctly. I got great feedback which helped me with my decisions that were indecisive. It is essential to have other people’s perspective of the project for opinions and refinement especially experienced people in the construction industry.
People that I e-mailed are as follows;

Step 2: Research

Some areas of the project required expert information as I did not know the answers to the desired information. The following pages are based on the communication skills I had with other people to fulfil my project correctly. I got great feedback which helped me with my decisions that were indecisive. It is essential to have other people’s perspective of the project for opinions and refinement especially experienced people in the construction industry.
People that I e-mailed are as follows;

Step 3: Calculations

I needed to work out the calculations of each triangle the dome consists of, based on the radius. There a various types of domes. From 1V to 6V the higher the number the more triangles there are therefore the dome will be more round in shape. I choose 2V which is ten 92.71mm equilateral triangles and thirty 81.92mm isosceles triangles. These account for a 150mm 2V radius dome. I used the desert dome calculator to do the job for me

Step 4: Prototype

My prototype was to forsee how the project would look when complete. IT made me more confident on making the complex design.
Materials used in the task;
  Pritt-PowerPritt - €4.99
  Fold back clips - €0.99 (x2)
  White card         - €0.40 (x4)
  Red card            - €0.50 (x5)
  Kwik-Fix glue    - €1.99

  Pros and con
What I like about my prototype was as follows;
   The geodesic dome is an impressive structure and pleasant to the eye,
   The method I used to construct it,
   The size was ideal (2V) and 150mm (Radius).
Problems and dislikes of my project were;
   The transparency as I felt my project would look visually better if it was transparent,
   The joints were sticking out a lot from the inside and this would effect the look if the project were to be transparent. To aid this          
    problem I removed the glue tabs and instead used a dense glue, silicone.

How to

Step 1 - Using the calculations mark them out on the card. I found using a ruler took too long so I decided to print the triangles out instead.(Remember to extend by 1cm for the glue tabs)
Step 2 - Cut the triangles out using a scissors making sure to angle the glue tabs back so they don't converge when folding them.
Step 3 - Label the folded tabs with (A) and (B) so you can stick the A's to A's and the B's to B's. The white triangle should be all B's.       On the red triangles the larger side 92.71mm should be also marked with B's. The other sides shall be marked with A's. This will avoid confusion, hopefully :P . Refer to the calculation page picture.
Step 4 - When all glue tabs are glued correctly it should look like a hexagon pac-man. The gap allows the pentagon to pop up and achieve the dome shape.
Step 5 - I used fold back clips to secure the final joint along with glue as it intended to seperate.
Step 6 - Now we have to make the base. Get a circular piece of cardboard a small bit larger than the diameter of the dome. 
e.g,  Dome= 30cm diameter.........Circle cardboard = 33cm diameter.
An interior circle must be drawn of 30cm so we know where to lay out base triangles. Using a compass I applied 92.71mm on the interior circle and marked a start point. From that point I marked another 92.71mm all around this circle which gave me the domes base.
Step 7 - From there I began the process of constructing the dome. I also used the fold back clips to secure each joint as they tended to pull away from each other.
Step 8 - For the final pentagon to be installed (The cap) I has to cut a circle out from the bottom of the dome which allowed access to the interior of dome thus allowing me to glue the last piece in.
Step 9 - Mission complete :D.

Step 5: Making of the Dome

The following equipment is what I used to construct the dome.
1. Rough and smooth flat file.
2. Bench saw
3. Clear silicone
4. Sharp blade
5. Low tack tape
The acrylic has to be cut in two triangles, like the template showed below. 30 triangles called A, and 10 triangles called B using the bench saw.

Then I filed them down using the rough file first leaving about 2mm between the line and filed area, then using the smooth file I filed to the line                      

I then masked the triangle with low tack tape to protect them from the silicone excess in the joints. I then cut the tape very close to the edge with a sharp blade.

Step 6: Making of the Dome

 I turned the tape covered triangles to the side of unsheltered acrylic and applied more tape along the two smaller edges of them, leaving half of the tape exposed to attach another triangle, making a hinge between them.
When five of the triangles are united with tape hinges along the small edges of them, the last step is to raise the triangles until the last hinge connects and the pentagonal pyramid is achieved.
There is now exposed acrylic between the masked acrylic triangles. I filled these gaps with silicone and removed the excess with a wipe. I repeated this process in all joints. It was essential to leave the pieces aside for at least 24 hours so that the silicone was cured.
I then got two pyramids and linked them together using triangle B. Again I placed silicone within the vacant joints and waiting 24 hours. Once I mastered the technique it was just a case of repeating the method until the dome was complete. The last pyramid (the cap/top) is the hardest to install due to a sum of errors. It may be necessary to make small refinements by using fine sandpaper or a smooth file.

Step 7: Making of the Dome

I cut the excess silicone off the joints leaving it flush with the triangles with a sharp blade.  Some joints came out while removing the tape.  I refilled these exposed joints using a new nozzle for the silicone giving me more precision.

Next was assembling the base for the dome itself and accessories to be place on.  I stuck 2 pieces of 56x46cm MDF together while then screwing them together using counter sinks to have the screw flush or below the board.  I placed soft bumpers on the underside  of my base to -protect and prevent damage to the board.  

For the circuit board I chiseled out a hole to fit the circuit board using a bevel chisel to fit the circuit and a clear piece of acrylic.
The Circuit board is 5x5cm so I marked that out first on the board, then I expanded out the marking by 5mm to support the acrylic.
I chiseled out the original markings of a depth of 1.5cm for the circuit board to be placed in, the second marking of a depth of 3mm to support the acrylic and have it flush with the board.

Step 8: Making of the Dome

 I placed the circuit box on the board and securing it with 4 screws as shown in the photos. I made sure the wires from the circuit box could reach the chiseled fitting before installing the box onto the board. From there I wired the output wires in parallel around the board securing them with wire pins. The ground lights that enhance the appearance of the dome at night were constructed using an aluminium L-bracket cut to size using a hacksaw. I drilled a hole in the back of the cut sized brackets to mount them onto the board using a screw and another hole on the other side for the LED to be mounted onto using a LED holder. In addition I glued a bottle cap with a hole pre-drilled over the position of the LED  to present it more like a spotlight.

The paint I used was a stone textured pebble finish giving the base a nice gravelly appearance on the outside. I also added sticky foam to act as grass. I also added cool little features such as a boxing ring, stand, lego men, signs and flooring.

Step 9: The Circuit

The circuit I assembled is the main part of my project. It enhances the structure at night time, which is required, by switching on all the lights when dark (night time). An LDR (Light Dependant Resister) are electronic components whose resistance is high in dark and low in light (extracted from my school technology book). With a few simple tweaks the circuit could be reversed and the resistance would be low in dark and high in light allowing the LEDs (Light-Emitting Diodes) to turn on when dark.

I chose to wire my LEDs in parallel as this would ensure that if a fault arose in one of the LEDs it would not affect any of the others. This is essential in important events such as boxing as the game would not be able to continue without a constant supply of light. Of course a generator would be another suitable solution but it’s always good to have extra security. I consulted my maths teacher about this topic on how to wire it correctly as he is also a physics teacher who knows a lot about this subject. This circuit is located on the instructions manual under the heading 2.Light Sensor. The board is called the TRANSISTOR PROJECT BOARD made in Middlesex University.
Soldering the Board
It is essential to solder the board correctly in order for it to function properly. I downloaded a PDF. File and learnt about cold joints and how to avoid or fix them. There are no cold joints on my board as I distinguished using the diagram on Page 9 of the SMD Soldering file. I also learnt not to apply solder to the iron and then to the board but corrected this error by applying the solder to the metal contacts.

My circuit is powered by a 9v battery and in result I lowered the resistance using ohms law. Calculations below.

1 LED = 20Ma 
Power source = 9v

2 LED's = 7.2v -> left over = 1.8v
Resistance = voltage diveded by Current

= 1.8
  ____   = 90 ohms.

I added a knob onto the variable resister to make it look more professional and cut the variable resister down to have flush with the surface it was mounted onto. I also added an override switch/kill switch so power would not be wasted. It also gives more control over the circuit. I enclosed the whole circuit in a neat box that my teacher gave me. Everything except the Transistor project board was stored in this box. I drilled a small little hole in the side of the box for the wires to go into.

Step 10: Information

MDF - Household
Acrylic - School
Silicone - €2.99 (Woodies DIY)
Floor protectors - €1.99 (Topline) for underside of base
Low tack tape - €2.99 (Topline)
Pebble spray paint - €11.99 (Woodies DIY)
String - Household
Screws - Household
Foam - €0.50c (easons)
Wood - Household
L-Bracket - Household
Bottle caps - Local swimming pool (Don't ask :P)
LEGO - Household
Toothpicks - Household
Blue/Red paint - Art teacher
Wood glue - €1.99 (Topline)
Box enclosure - Household

Total = €23.45                Budget = €25.00             Under budget = €1.55

x4 - High bright LEDs - 0.44c
x4 - LED holders - 0.11c
x1 - Transistor - Circuit board package
x1 - 1k resistor - Circuit board package
x1 - 100 ohms resistor - Circuit board package
x1 - Variable resistor - 0.99c
x1 - Diode - Circuit board package
x1 - Battery hook up - Circuit board package
x4 - 1.5v batteries - €3.99
x1 - Battery case - 0.50c
x1 - Knob - 0.11c
x1 - Switch - 1.05c
x1 - LDR - Circuit board package

Tools used
Soldering iron,
Various pliers,
Wire strippers,
Mortiser - for cutting square holes on the boxing ring,
Mastic gun,
Bench saw,
Various files,
Bench and portable drill,
Exacto knife,
A pin hammer.

Step 11: Conclusion

I am happy that my project has satisfied the final brief and specifications. The project incorporates an electronic system along with construction skills. The project is strong and durable, and finish is of high quality. I was able to manufacture the entire project within the technology classroom apart from the painting. The use of the clear acrylic has made the project look very good especially at night when the lights are shone upon it. I believe the project has applications in the real world and could be utilized as a home.

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