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Zane Middle School pendulum wave machine

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Figure 1: The Crystal Pendulum Wave Machine


Background[edit]

The Pendulum Wave Machine is a device meant to provide educational value regarding the function of basic wave patterns. The machine's creator is Team Outback from Humboldt State University's Spring 2017 Engr215 Introduction to Design Class. The client of the project is the Catherine L. Zane Middle School in Eureka, CA and the point person for the project is Ken Pinkerton. The pendulum wave machine makes its debut at the Humboldt Math Festival on the 29th of April, 2017. Zane wishes for the wave pendulum to be able to provide educational value to the Humboldt Community and serve as a tool in demonstrating basic wave patterns (sine, cosine, etc.) and behavior as it will ultimately serve as a visual aid for students at the school.

Project Objective[edit]

Team Outback’s objective is to design a model of a wave pendulum machine that will be able to clearly demonstrate how waves behave. The goal of the model is to educate both children at Zane Middle School, as well as the greater community at the Humboldt Math Festival and in children the middle school on how different time periods can affect the motion of waves and influence their behavior.

Criteria[edit]

The criteria listed below were presented by the client representative of the project Mr. Ken Pinkerton.

Criteria Weight (#)
Functionality 10
Safety 10
Durability 10
Cost 9
Portability 8
Storability 8
Inspiration 8
Education 8

Description of final project[edit]

The pendulum wave machine is a model that utilizes LED lighting features, crystal pendulums, and a collapsible design as the final solution to meet the necessary criteria. The model is comprised of a hollow wooden base with a collapsible a-frame structure that holds a beam suspending 8 multifaceted glass pendulums. The frame also contains an LED light circuit that shines directly on each pendulum to create unique lighting effects as the pendulums swing from side to side.

The wooden base of the pendulum is designed for the model to be collapsible and fit within the base of the pendulum. As seen in Figure 5-1, the base of the model measures 36” long and 18” wide. It is constructed using a frame built from 2x4” pieces of wood and uses two faces of plywood of ½” thickness using 8x2½” screws. The base has holes of ⅞” diameter drilled uniformly into the base directly under each pendulum as to allow for the LED lighting to reach from the inside of the base to the hanging pendulums. The top of the base also has 4 holes of 3” depth, 3” away from each corner of the base at a 45-degree angle. These holes serve as the support structure for the metal A-frame. The wooden base is coated in a water-based rubbing stain and finish.


Figure 2 : Inside view of the Crystal Pendulum Wave Machine


The A-frame components of the model are made to hold the beam that suspends the pendulums. The steel metal A-frames thread through the wooden beam and are able to swivel freely within the wooden beam to allow them to lay completely flat, therefore catering to the collapsible feature of the model. The A-frame is constructed using 66” long metal rods, bent at an approximately 110-degree angle on either side of the wooden beam in which they rest. The steel rods are strong enough to support up to 30 pounds and are rust resistant. The wooden beam that supports the pendulums is a 2x4” wooden beam of 30” in length. The beam has a ¼” hole drilled 1” down the side of the beam on both ends to allow for the A-frame to rest within the beam. The top of the beam has two smalls holes that are 40mm apart drilled through it starting 61mm from the edge of the beam. Strings are threaded through each hole drilled in the beam and two strings connect to each pendulum.


Figure 3 : Collapsable A-frame and beam


The LED light structure has components of wires, resistors, LED lights, heat shrinks, USB port charger, and wood. 5mm diameter LED lights are used and wired together in parallel. The lights are in series with 150-ohm resistors. The voltage drop across each light and resistor is 2.85 Volts and current of 19 mA. To avoid fire hazards, heat shrink is placed around all of the wires. The circuit is then attached to a wooden board to hold it in place. This board can easily be attached to the inside of the base of the pendulum. The wooden board with circuit is pushed through the predrilled holes in the base and nailed for permanent placement.

Figure 4 : LED and electrical components

Machine Assembly[edit]

Figure 5 gives a step by step instructions on the assembly process of the pendulum wave machine.

Fig 5: Instructions for pendulum wave machine assembly.

AutoCAD Design[edit]

Fig 6: AutoCAD drawing by Maria Garcia showing the basic plan of machine's base box.

The beginning of the pendulum wave machine began with a basic 3D modeling plan of the base of the pendulum in AutoCAD. This step was crucial in being able to synthesize the issue and properly determine the right dimensions. Much of the work that goes into building a pendulum wave machine is making sure that all measurements are equal so that they can create a stable and level machine. These measurements are especially important because they ensure the functionality of the machine.

Fig 7: AutoCAD drawing by Lorenz Hernandez showing the plan for the lighting components.

Costs[edit]

Quantity Material Cost ($) Total ($)
2 Plywood

19.99

39.99
1 2x4 Wood

6.59

6.59
2 Metal Rod

7.49

14.98
1 Box of 8x2-1/2 Deck Screws

9.99

9.99
1 Wood Stain

8.99

8.99
1 Wood Glue

5.99

5.99
1 30mm Crystals Pack

13.98

13.98
1 5 mm LED Lights

4.95

4.95
1 P-Line 30 lbs (String)

Donated

0
1 Gliders

Donated

0
1 Circuit Wires

Donated

0
16 150 Ohm Resistor

Donated

0
1 USB Wall Charger

Donated

0
1 Heat Shrink

Donated

0
Total Cost $109.78

Pendulum Wave Machine Construction[edit]

Materials[edit]

The pendulum wave machine, although very complex in construction, and incredibly interesting in action, requires very little in actual materials to construct. The materials shown in Figure 8 and instructions listed below shows how a wave machine can be constructed from very little resources.

Fig 8: A collection of the total materials needed to construct a pendulum wave machine


How To Build[edit]

Steps to assemble
1. Start by creating the desired dimensions of the machine on paper, so that all necessary measurements can be made and finalized before physical construction begins as to minimize any wrong cuts.  
2. Measure out desired dimensions of the machine on the wood to prepare for all necessary cuts and drills. Also, mark which areas of each piece of wood will be bound to another piece to build the frame. Then make all desired cuts on wood and piece the wood together in the manner previously planned out and marked in Step 1 to create the boxed frame for the base of the pendulum. Then cut out and attach the plywood on either side of the frame to create the full base of the pendulum. Also be sure to drill the holes for the LED lights to fit. For a final touch on the base, make sure to drill the holes that will hold the a-frame on the top face of the pendulum.  
3. Bend the metal rods to form "A" like angles. Then take the wood you want to serve as the beam and make the appropriate measurements and create the divots in the beam of wood so that the beam can hold the circular shape of the rod. Then take pre-constructed blocks of wood and attach them to the beam so that the a-frame can swing comfortably in the divots, but not be able to become attached from the beam.  
4. Clamp weight around paper platform pendulum  
5. Create the LED light series using high-beam lights, wire, resistors, and heat shrink.  

Maintenance[edit]

Maintenance cost for this project will be kept at the very minimum. The annual cost of maintenance for the Pendulum Wave Machine is approximately $5.30 as demonstrated by the table below.


Quantity Item Cost ($) Replacement Time (yrs) Total Cost ($/yr)
1 Crystal Pendulum 1.74 0.50 3.48
1 Cord (yd) 0.05 1.00 0.05
48 LED Light 0.05 7.00 0.34
1 Wood Stain 9.99 7.00 1.43
Total 5.30

Troubleshooting[edit]

This is only how to troubleshoot basic operation. For complex issues, contact Team Outback.

Problem Suggestion
Pendulum cracks Connect new pendulum to the cord
Line snaps Attach new line
LED light goes bad Attach new LED

Results[edit]

The final model of the Pendulum Wave Machine is a fully functional educational tool. The pendulum is fully storable, portable functional, and compliant with predetermined safety standards. The model is also very heavy-duty and in standards with durability. The pendulum is able to create basic wave patterns with a uniform harmonic pattern. When members of the community use the machine, they are better able to visual wave patterns and understand what affects waves. For example, when presented with the model at the Humboldt Math Festival on April 29th, 2017, member's of the community were able to see the different lengths of string from which each pendulum swing, and thus able to see how the formula for a period of a wave applies to reality.


Figure 9 : A group of children learning about basic wave functions.


Figure 10: A young boy learning how to operate the Pendulum Wave Machine.


Figure 11: Most cannot resist smiling when watching the machine in action.

Suggestions for future changes[edit]

IDEAS:

  • Building a less portable pendulum wave machine, therefore having a fixed a-frame, may increase durability.
  • Choosing redwood wood as a base will also increase its durability.
  • Having a smaller size pendulum may improve its portability and storability.
  • Acquiring skills and knowledge in electronics may improve the LED light effects. Using different color LED lights that attracts children may increase inspiration.

References[edit]

See Help:Footnotes for more.