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The Solar Swing is a box-shaped oven that has one wall that is taller than the rest, creating a top face that is slanted downwards. A pane of tempered glass is used as the glazing on the top face of the oven. The window serves as the oven’s door by swinging open from the top. The oven has three fold-out, removable, reflective panels that are held onto the box by aluminum framing and plastic bolts. The outside box is made from sheet metal, and the insulating material in the interior is 1 ½” Rmax foam board. On the interior faces of the oven, stapled to the Rmax, is reflective mylar. Inside the oven is a swing that is suspended from a wooden dowel. It is on this swing that the baking tray/pan/etc. is set. As the oven is propped at different angles, the swing allows the cooking surface to remain parallel to the ground.  
The Solar Swing is a box-shaped oven that has one wall that is taller than the rest, creating a top face that is slanted downwards. A pane of tempered glass is used as the glazing on the top face of the oven. The window serves as the oven’s door by swinging open from the top. The oven has three fold-out, removable, reflective panels that are held onto the box by aluminum framing and plastic bolts. The outside box is made from sheet metal, and the insulating material in the interior is 1 ½” Rmax foam board. On the interior faces of the oven, stapled to the Rmax, is reflective mylar. Inside the oven is a swing that is suspended from a wooden dowel. It is on this swing that the baking tray/pan/etc. is set. As the oven is propped at different angles, the swing allows the cooking surface to remain parallel to the ground.  


[figure of design]
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===Building and Implementation Instructions===
===Building and Implementation Instructions===
This is where we tell you how to build the oven.
 
To use to solar oven, it first needs to be placed with the slanted top facing the sun for maximum temperatures. The Panels are then opened and lifted to that they will direct light into the oven. The oven should be left and allowed to heat before food is placed in the oven. Once the oven has heated up, the glass lid should be lifted, being careful not to touch the panels or the glass. Place the cooking pans in the oven and approximate cooking time. To clean and store the oven, wait for the oven to cool before cleaning it out. The panels can be folded up and placed on top of the oven. The oven can now be rolled to its storage area. The oven conducts heat and will be hot to the touch, so children should be monitored as they use it.
 
 
====The Box====
The box is made from recycled sheet metal from a salvaged file cabinet and side panels from a range stove. Dimensions of the box can be modified, depending on the materials available and the optimum angle for the glazing. 
 
=====Determining the Angle for the Glazing=====
The glazing is the surface through which the rays of light will travel into the box. The glazing of solar ovens is often set at an angle instead of parallel to the ground. When determining the angle at which the glazing should be tilted, it is important to consider where you are located; the angle of the sun in the sky varies widely depending upon your latitude and longitude. The website http://www.susdesign.com/sunangle/ can be used to determine the elevation of the sun in the sky for your location. Enter your zip code and determine the sun’s altitude for various times during the day and throughout the year to get an idea of the range of the sun’s location. For example, the altitude of the sun in Arcata, California varies (during mid-day hours) from approximately 20 degrees in the winter months up to approximately 70 degrees in the summer months.
Since the oven is for an elementary school and likely will not be used as much during the summertime, the average altitude of the sun in Arcata, California during the oven’s projected hours of use is approximately 40 degrees. This is represented by h, the elevation angle, in Figure 5.SOMETHING  below.
 
[[Image:AEFprevfilt2.jpg]]
 
The most powerful rays from the sun are direct rays, as opposed to reflected rays. An oven that has its glazing at an angle of z degrees from the horizontal (the zenith angle; see Figure 5.SOMETHING ) will bring in the most direct rays and be the most efficient. To find the best angle of the glazing for the oven, determine the average elevation angle h for your location and subtract h degrees from 90 degrees. This zenith angle z is a good angle for the glazing. (see Figure 5.SOMETHING below)
 
[[Image:AEFprevfilt2.jpg]]
 
The Solar Swing is designed so that it can be propped up along its back edge so that more direct sun rays enter through the glazing while the food being prepared remains parallel to the ground. The Solar Swing can be propped up to approximately FIND MAX TILT degrees, which creates a range for the glazing’s angle. When building the oven, cutting the cost of materials and the desire to use as many recycled materials as possible may be high priorities. Due to the limited amount of sheet metal and, thus, limited dimensions, The Solar Swing has its glazing at approximately 12 degrees. The tilting effect allows the glazing to range from 12 degrees to 12 + FIND MAX TILT degrees, which approaches the desired angle z. 
 
=====Cutting the Metal=====
The metal can be cut using metal shears. The dimensions will vary, depending on the angle that the glazing will be set at. The base and front wall likely will be the same dimensions as The Solar Swing’s, while the two side walls and the back wall will vary.
Base – 23.75” x 30”
Front Wall – 9” x 30”
Two Side Walls – 23.75” x 9” x 24.25” x 14”
Back Wall – 14” x 30”
Use trigonometry to determine the height of the back wall. An imaginary triangle is created if you draw a horizontal line from the upper corner where the front wall and side wall meet across to the back wall. The base of this triangle is the width of the oven (23.75”), and the angle z is the angle that the glazing will be set at (see Figure 5.SOMETHING).  The height of the triangle (Y) can be determined by the following equation:
Y = 23.75 * tan z
The height of the back wall should be:
H = 9 + Y
Lay out the five pieces once you are finished (Figure 5.SOMETHING).
 
[[Image:AEFprevfilt2.jpg]]
 
Note: The remainder of these directions will be depicted as if The Solar Swing is being duplicated at its original dimensions. As the glazing angle and dimensions vary, the measurements given in the following sections will need to be modified. 
 
=====Cutting the Aluminum=====
Using tin snips, begin cutting the L-shaped aluminum siding to the correct lengths:
2 @ 9”
2 @ 14”
2 @ 23.75”
6 @ 30”
4 @ 24.25”
 
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=====Riveting the Box=====
The box’s walls are secured by riveting the walls to the L-shaped aluminum. Drill holes through the aluminum and the sheet metal at approximately 4” intervals and use a riveter to secure them to each other. Do this at all places where walls meet, but leave one side wall off for now.
Along the top perimeter of the box, secure the L-shaped aluminum so that the L faces the ground. Then, rivet another piece of L-shaped aluminum around each of the four sides so that the L faces the inside of the box. This creates a frame for the glazing to rest in (see Figure 5. SOMETHING below). Take care to place your rivets for this glazing frame closer to the interior edge of the frame, as more aluminum framing will be slid underneath the frame from the outside later on in the process.
 
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====The Insulation====
Insulation for The Solar Swing is made up of 1.5” thick Rmax insulation board, often available from hardware stores in 4’ by 8’ sheets. Use a measuring tool and a drawing tool to draw the outlines of the five pieces needed. The dimensions of these pieces are as follows:
1 @ 23.25”x29.5”
1 @ 29.5”x7”
1@ 29.5”x12”
2@ 20.25”x7”x20.7”x12”
A circular indent must be cut into each side wall with an exactoknife so that the wall fits snugly against one of the two flanges that support the dowel that holds up the swing. Use the flange to trace the circle out on the Rmax board. The flange should be placed about 1” below the slanted edge of the Rmax and 9.5” inwards from the taller edge of the Rmax. Cut out just enough foam so that the flange sits flush with the Rmax (see Figure 5. SOMETHING below).
 
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Next, use a 3/4” drill bit to drill a hole through the center of each of the two indents made (see Figure 5. SOMETHING below). This is the hole through which the dowel will slide.
 
[[Image:AEFprevfilt2.jpg]]
 
Now that all five pieces of insulation are ready, cut pieces of mylar that are large enough to “gift wrap” each piece of Rmax. Secure the mylar to the Rmax using a stapler(see Figure 5. SOMETHING below).
 
[[Image:AEFprevfilt2.jpg]]
 
The wrapped piece of Rmax that serves as the base can now be placed inside the box (see Figure 5. SOMETHING below).
 
[[Image:AEFprevfilt2.jpg]]
 
====The Swing====
The swing is made of a full-sized baking sheet (18”x26”). The sheet is suspended by a 3/4” wooden dowel that is supported by the two flanges. Cut the wooden dowel so that it is 30” long. This can be done with a hand-saw (see Figure 5. SOMETHING below).
 
[[Image:AEFprevfilt2.jpg]]
 
To thread the wooden dowel, place one of the flanges on the floor, step on it, and press and twist the dowel into the flange’s center. Before threading dowel onto the second flange, make sure the dowel is run through both pieces of the side wall insulation (see Figure 5. SOMETHING below).
 
[[Image:AEFprevfilt2.jpg]]
 
Use the flange holes cut in the insulation to determine where the flanges will be secured to each of the side walls. Mark the flange’s perimeter and the locations of its holes onto the sheet metal. Drill into the sheet metal at the locations of the flange’s holes so that stainless steel bolts can fit through. Use the stainless steel bolts, washers, and nuts to secure the first flange to the side wall that is already riveted into the box’s structure.
Before the final wall can be put into place, two stainless steel hinges that support the glazing must be bolted to the back wall. Position each hinge on the exterior of the upper edge of the back wall, each at approximately 7” from the outside edges. Use tin snips to cut rectangles out of the aluminum framing so that the hinges are free to rotate in and out over the frame. The hinges must be bolted so that they leave a gap for the glazing and the stove gasket insulation. Drape the stove gasket along the inside of the frame and rest the pane of tempered glass on top. The hinge will be glued to the outside surface of the glass, so rest the hinge on top of the glass and mark the hinge’s position. Remove the gasket and glass, then drill holes for the hinges and fasten them into place with washers and nuts.
Slide the two side wall insulation pieces into place, then slide in the remaining wall of the box. Rivet the final wall into place.
To suspend the swing, drill a hole into each of the four corners of the cookie sheet so that the S-shaped hooks can fit through. Two galvanized, 5/8” wire rope clips are secured at each end of the dowel to support the chain that holds up the swing. Use two pieces of mason line to suspend the sheet. Each piece should be secured to two S-clips and should run up through the wire rope clip on the wooden dowel. Find the length of mason line needed to suspend the sheet, and then get two pieces of chain cut at a hardware store that match this length. Note that the string you use for the test suspension may stretch.
 
====The Panels====
The panels are made from three pieces of flat-surfaced, corrugated plastic. The plastic should be cut into three panels of the following dimensions:
1 @ 30”x20”
2 @ 24”x20”
Use silicone adhesive to glue sheets of mylar onto one surface of each panel (see Figure 5. SOMETHING below). Allow the glue to fully dry.
 
[[Image:AEFprevfilt2.jpg]]
 
Cut two more pieces of L-shaped aluminum siding 24.25” long. These will be used on the upper edge of the two side walls. Cut three more pieces that match the lengths of the three segments that make up the frame on the upper edge of the back wall.
Slide each of these between the two L-shaped pieces already secured to each side of the box’s upper perimeter. Use tin snips to cut away excess material along one side of the L on each piece of aluminum- the slid-in piece should create a gap with the existing frame that is just big enough to slide a corrugated plastic panel into it. Rivet the four slid-in pieces into place.
Next, slide the three panels into the holders created for them. Drill three holes in each panel that go through the panel’s bottom edge and each of the two pieces of L-shaped aluminum siding that hold the panel in place. Use long plastic bolts to slide through the frame and the panels. These will help secure the panels to the frame but are easily slid out, creating removable panels. Note that the aluminum siding is bendable. The housing for the panels can be adjusted as the oven is used to maximize the amount of sunlight entering the box.
 
====The Glazing====
The glazing is made of a 29.5”x23.75” piece of tempered glass. This likely will need to be ordered at a local glass dealer, as tempered glass cannot be easily and safely cut to different dimensions.
The glass will rest on ½” diameter stove gasket. Rivet the gasket inside of the frame on the top of the box (see Figure 5. SOMETHING below).
 
[[Image:AEFprevfilt2.jpg]]
 
Lower the glass into the frame and slide it upwards so that its upper edge hits the middle of each hinge. Use high-strength epoxy glue that works on glass and metal surfaces to glue the hinges to the outside of the glass. Also, glue a plastic handle to the lower edge of the glass. Allow the glue to fully dry.
 
====Finishing Touches====
Use a file and metal repair tape along any sharp edges of the oven.
Set a stove thermometer on the swing in the oven’s interior so that the oven’s temperature can be monitored.
Since this is a solar oven for elementary school children, a fun project is to allow the students to create magnets to decorate the outside of the box. Once the magnets are put on, the oven is ready to be tested (see Figure 5. SOMETHING below).
 
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==Results==
==Results==

Revision as of 06:07, 3 May 2011

Fig 1: The Solar Swing


Abstract

The Solar Swing is a project from Humboldt State University's Engineering 215 class. The Solar Swing is a solar oven designed to be implemented in elementary schools across the United States to give children confidence while they learn about solar technology and practice cooking skills.

Background

Locally Delicious is a group of ladies from Humboldt County, California who promote the local foods movement and strive to move away from industrial agriculture. They have helped to fund many local projects such as Food for People, which selects six local farmers to grow specific food for food banks, the Mobile Processing Unit for the Poultry Cooperative, and the Potawot Garden in Arcata.

The group gets their name from their first book, which aims to provide recipes and resources for residents of the north coast. They are currently working on their second book- Lunchbox Envy. The book is targeted towards parents, older children and their mentors. The goal is to create healthy lunches that kids will want to eat and includes projects that kids can do by themselves, with adults or at their school.

Locally Delicious contracted our team to design and implement a solar oven in Trinidad School to be used as an example for a do-it-yourself project to be included in Lunchbox Envy.

Project Definition

This project is a solar oven that can be replicated at elementary schools across the United States by adults with the possible help of the students. It must meet the client's criteria.

Project Criteria

The project criteria and constraints were considered by the both Operation S.O.S. and the client. The criteria were then weighted in order to determine the strengths and weaknesses of the Alternative Solutions.

Table 1: Project Criteria, Descriptions and Weights.

Criteria Description Weight
Oven Safety The oven must be safe for elementary school children and meet the school’s insurance policy. 10
Durability The oven must last for three to five years. 9
Efficiency The oven must thoroughly cook the food prepared by the Junior Chefs within their designated meeting times. 9
Portability The oven must be easily moved around the Trinidad School campus and fit into their storage space. 8
Cost Each team member contributes up to $75 and the client contributes up to $100, so the final cost cannot exceed $400. 7
Ease of Use The oven must be operable by the Junior Chefs grades fourth through sixth. 7
Effectiveness -teaching The oven must meet the Common Core Content Standards for English and Mathematics selected by the California Academic Content Standards Commission (http://www.scoe.net/castandards/). 6

Cost

Design Hours

The following chart includes how much time was spent in each section of the design process.

Figure 2: Total Hours Spent = 713

Building and Materials Costs

Table 2 includes the current retail value of the materials used as well as the cost that our team was able to produce it at.

Table 2: Material Costs

Quantity Material Source Our Cost($) Retail Cost ($)
1 Mylar Roll Ace Hardware 18.52 18.52
4 Corrugated Plastic Sheets Ellis Art & Engnrng 21.39 23.76
1 Full-sized baking sheet Angels of Hope Thrift Store 3.75 17.99
1 Tube of silicone adhesive Pierson's 2.32 2.58
1 4'x8'x1.5" Rmax foam sheet Pierson's 27.24 30.27
2 L-shaped aluminum connectors Ace Hardware 3.50 7.08
1 Bottle heat resistant black paint Ace Hardware 7.62 7.62
1 Roll of aluminum foil Ace Hardware 3.26 3.26
1 Oven thermometer Ace Hardware 8.71 8.71
1 Tube of caulk Ace Hardware 7.62 7.62
1 1/4" drill bit Ace Hardware 6.09 6.09
2 Bead corner drywall 8' Ace Hardware 6.08 6.08
2 Aluminum rivets 100 packs Ace Hardware 5.24 5.24
8 Flange bolts Ace Hardware 4.80 4.80
8 Flange nuts Ace Hardware 4.40 4.40
8 Flange lock washers Ace Hardware 1.04 1.04
8 Flange flat washers Ace Hardware 0.96 0.96
2 Floor flange 1/2" galvanized Ace Hardware 13.06 13.06
2 Wire rope clip Ace Hardware 6.52 6.52
1 3/4" wooden dowel Ace Hardware 3.80 3.80
2.6 foot of chain Ace Hardware 7.07 7.07
4 large S-hooks Ace Hardware 6.08 6.08
2 Stainless steel hinges Ace Hardware 23.96 23.96
6 Hinge bolts Ace Hardware 2.94 2.94
6 Hinge nuts Ace Hardware 1.50 1.50
9 foot of stove gasket (large) Ace Hardware 17.55 17.55
4 foot of stove gasket (small) Ace Hardware 4.32 4.32
9 Plastic bolts Ace Hardware 5.40 5.40
1 metal file cabinet Scrap yard 0.00 60.00
1 Range oven bottom Scrap yard 0.00 55.00
2 Drip edge, galvanized Ace Hardware 8.26 8.26
1 Roll of nylon twine Ace Hardware 4.68 4.68
1 Pane of tempered glass 29.5"x23.75" Eureka Glass 35.70 35.70
1 Tube of epoxy glue Ace Hardware 4.68 4.68
1 Roll of metal repair tape Ace Hardware 5.87 5.87


Totals $286.95 $422.42

Maintenance Costs

The following two tables describe the annual operation and maintenance costs associated with The Solar Swing. Table 3 shows current retail values of possible replacement materials. Table 4 shows the annual labor involved in maintaining The Solar Swing.

Table 3:Material Costs

Material QTY Material Cost
25'x48" Mylar Roll One roll 18.52
Silicone 1 tube 2.58
Total $21.10

Table 4:Labor Costs

Task Time Spent (hrs/year)
Cleaning of Oven 13
Replacing Mylar 2
Total 15

Final Design

The Solar Swing is a box-shaped oven that has one wall that is taller than the rest, creating a top face that is slanted downwards. A pane of tempered glass is used as the glazing on the top face of the oven. The window serves as the oven’s door by swinging open from the top. The oven has three fold-out, removable, reflective panels that are held onto the box by aluminum framing and plastic bolts. The outside box is made from sheet metal, and the insulating material in the interior is 1 ½” Rmax foam board. On the interior faces of the oven, stapled to the Rmax, is reflective mylar. Inside the oven is a swing that is suspended from a wooden dowel. It is on this swing that the baking tray/pan/etc. is set. As the oven is propped at different angles, the swing allows the cooking surface to remain parallel to the ground.

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Building and Implementation Instructions

To use to solar oven, it first needs to be placed with the slanted top facing the sun for maximum temperatures. The Panels are then opened and lifted to that they will direct light into the oven. The oven should be left and allowed to heat before food is placed in the oven. Once the oven has heated up, the glass lid should be lifted, being careful not to touch the panels or the glass. Place the cooking pans in the oven and approximate cooking time. To clean and store the oven, wait for the oven to cool before cleaning it out. The panels can be folded up and placed on top of the oven. The oven can now be rolled to its storage area. The oven conducts heat and will be hot to the touch, so children should be monitored as they use it.


The Box

The box is made from recycled sheet metal from a salvaged file cabinet and side panels from a range stove. Dimensions of the box can be modified, depending on the materials available and the optimum angle for the glazing.

Determining the Angle for the Glazing

The glazing is the surface through which the rays of light will travel into the box. The glazing of solar ovens is often set at an angle instead of parallel to the ground. When determining the angle at which the glazing should be tilted, it is important to consider where you are located; the angle of the sun in the sky varies widely depending upon your latitude and longitude. The website http://www.susdesign.com/sunangle/ can be used to determine the elevation of the sun in the sky for your location. Enter your zip code and determine the sun’s altitude for various times during the day and throughout the year to get an idea of the range of the sun’s location. For example, the altitude of the sun in Arcata, California varies (during mid-day hours) from approximately 20 degrees in the winter months up to approximately 70 degrees in the summer months. Since the oven is for an elementary school and likely will not be used as much during the summertime, the average altitude of the sun in Arcata, California during the oven’s projected hours of use is approximately 40 degrees. This is represented by h, the elevation angle, in Figure 5.SOMETHING below.

AEFprevfilt2.jpg

The most powerful rays from the sun are direct rays, as opposed to reflected rays. An oven that has its glazing at an angle of z degrees from the horizontal (the zenith angle; see Figure 5.SOMETHING ) will bring in the most direct rays and be the most efficient. To find the best angle of the glazing for the oven, determine the average elevation angle h for your location and subtract h degrees from 90 degrees. This zenith angle z is a good angle for the glazing. (see Figure 5.SOMETHING below)

AEFprevfilt2.jpg

The Solar Swing is designed so that it can be propped up along its back edge so that more direct sun rays enter through the glazing while the food being prepared remains parallel to the ground. The Solar Swing can be propped up to approximately FIND MAX TILT degrees, which creates a range for the glazing’s angle. When building the oven, cutting the cost of materials and the desire to use as many recycled materials as possible may be high priorities. Due to the limited amount of sheet metal and, thus, limited dimensions, The Solar Swing has its glazing at approximately 12 degrees. The tilting effect allows the glazing to range from 12 degrees to 12 + FIND MAX TILT degrees, which approaches the desired angle z.

Cutting the Metal

The metal can be cut using metal shears. The dimensions will vary, depending on the angle that the glazing will be set at. The base and front wall likely will be the same dimensions as The Solar Swing’s, while the two side walls and the back wall will vary. Base – 23.75” x 30” Front Wall – 9” x 30” Two Side Walls – 23.75” x 9” x 24.25” x 14” Back Wall – 14” x 30” Use trigonometry to determine the height of the back wall. An imaginary triangle is created if you draw a horizontal line from the upper corner where the front wall and side wall meet across to the back wall. The base of this triangle is the width of the oven (23.75”), and the angle z is the angle that the glazing will be set at (see Figure 5.SOMETHING). The height of the triangle (Y) can be determined by the following equation: Y = 23.75 * tan z The height of the back wall should be: H = 9 + Y Lay out the five pieces once you are finished (Figure 5.SOMETHING).

AEFprevfilt2.jpg

Note: The remainder of these directions will be depicted as if The Solar Swing is being duplicated at its original dimensions. As the glazing angle and dimensions vary, the measurements given in the following sections will need to be modified.

Cutting the Aluminum

Using tin snips, begin cutting the L-shaped aluminum siding to the correct lengths: 2 @ 9” 2 @ 14” 2 @ 23.75” 6 @ 30” 4 @ 24.25”

AEFprevfilt2.jpg

Riveting the Box

The box’s walls are secured by riveting the walls to the L-shaped aluminum. Drill holes through the aluminum and the sheet metal at approximately 4” intervals and use a riveter to secure them to each other. Do this at all places where walls meet, but leave one side wall off for now. Along the top perimeter of the box, secure the L-shaped aluminum so that the L faces the ground. Then, rivet another piece of L-shaped aluminum around each of the four sides so that the L faces the inside of the box. This creates a frame for the glazing to rest in (see Figure 5. SOMETHING below). Take care to place your rivets for this glazing frame closer to the interior edge of the frame, as more aluminum framing will be slid underneath the frame from the outside later on in the process.

AEFprevfilt2.jpg

The Insulation

Insulation for The Solar Swing is made up of 1.5” thick Rmax insulation board, often available from hardware stores in 4’ by 8’ sheets. Use a measuring tool and a drawing tool to draw the outlines of the five pieces needed. The dimensions of these pieces are as follows: 1 @ 23.25”x29.5” 1 @ 29.5”x7” 1@ 29.5”x12” 2@ 20.25”x7”x20.7”x12” A circular indent must be cut into each side wall with an exactoknife so that the wall fits snugly against one of the two flanges that support the dowel that holds up the swing. Use the flange to trace the circle out on the Rmax board. The flange should be placed about 1” below the slanted edge of the Rmax and 9.5” inwards from the taller edge of the Rmax. Cut out just enough foam so that the flange sits flush with the Rmax (see Figure 5. SOMETHING below).

AEFprevfilt2.jpg

Next, use a 3/4” drill bit to drill a hole through the center of each of the two indents made (see Figure 5. SOMETHING below). This is the hole through which the dowel will slide.

AEFprevfilt2.jpg

Now that all five pieces of insulation are ready, cut pieces of mylar that are large enough to “gift wrap” each piece of Rmax. Secure the mylar to the Rmax using a stapler(see Figure 5. SOMETHING below).

AEFprevfilt2.jpg

The wrapped piece of Rmax that serves as the base can now be placed inside the box (see Figure 5. SOMETHING below).

AEFprevfilt2.jpg

The Swing

The swing is made of a full-sized baking sheet (18”x26”). The sheet is suspended by a 3/4” wooden dowel that is supported by the two flanges. Cut the wooden dowel so that it is 30” long. This can be done with a hand-saw (see Figure 5. SOMETHING below).

AEFprevfilt2.jpg

To thread the wooden dowel, place one of the flanges on the floor, step on it, and press and twist the dowel into the flange’s center. Before threading dowel onto the second flange, make sure the dowel is run through both pieces of the side wall insulation (see Figure 5. SOMETHING below).

AEFprevfilt2.jpg

Use the flange holes cut in the insulation to determine where the flanges will be secured to each of the side walls. Mark the flange’s perimeter and the locations of its holes onto the sheet metal. Drill into the sheet metal at the locations of the flange’s holes so that stainless steel bolts can fit through. Use the stainless steel bolts, washers, and nuts to secure the first flange to the side wall that is already riveted into the box’s structure. Before the final wall can be put into place, two stainless steel hinges that support the glazing must be bolted to the back wall. Position each hinge on the exterior of the upper edge of the back wall, each at approximately 7” from the outside edges. Use tin snips to cut rectangles out of the aluminum framing so that the hinges are free to rotate in and out over the frame. The hinges must be bolted so that they leave a gap for the glazing and the stove gasket insulation. Drape the stove gasket along the inside of the frame and rest the pane of tempered glass on top. The hinge will be glued to the outside surface of the glass, so rest the hinge on top of the glass and mark the hinge’s position. Remove the gasket and glass, then drill holes for the hinges and fasten them into place with washers and nuts. Slide the two side wall insulation pieces into place, then slide in the remaining wall of the box. Rivet the final wall into place. To suspend the swing, drill a hole into each of the four corners of the cookie sheet so that the S-shaped hooks can fit through. Two galvanized, 5/8” wire rope clips are secured at each end of the dowel to support the chain that holds up the swing. Use two pieces of mason line to suspend the sheet. Each piece should be secured to two S-clips and should run up through the wire rope clip on the wooden dowel. Find the length of mason line needed to suspend the sheet, and then get two pieces of chain cut at a hardware store that match this length. Note that the string you use for the test suspension may stretch.

The Panels

The panels are made from three pieces of flat-surfaced, corrugated plastic. The plastic should be cut into three panels of the following dimensions: 1 @ 30”x20” 2 @ 24”x20” Use silicone adhesive to glue sheets of mylar onto one surface of each panel (see Figure 5. SOMETHING below). Allow the glue to fully dry.

AEFprevfilt2.jpg

Cut two more pieces of L-shaped aluminum siding 24.25” long. These will be used on the upper edge of the two side walls. Cut three more pieces that match the lengths of the three segments that make up the frame on the upper edge of the back wall. Slide each of these between the two L-shaped pieces already secured to each side of the box’s upper perimeter. Use tin snips to cut away excess material along one side of the L on each piece of aluminum- the slid-in piece should create a gap with the existing frame that is just big enough to slide a corrugated plastic panel into it. Rivet the four slid-in pieces into place. Next, slide the three panels into the holders created for them. Drill three holes in each panel that go through the panel’s bottom edge and each of the two pieces of L-shaped aluminum siding that hold the panel in place. Use long plastic bolts to slide through the frame and the panels. These will help secure the panels to the frame but are easily slid out, creating removable panels. Note that the aluminum siding is bendable. The housing for the panels can be adjusted as the oven is used to maximize the amount of sunlight entering the box.

The Glazing

The glazing is made of a 29.5”x23.75” piece of tempered glass. This likely will need to be ordered at a local glass dealer, as tempered glass cannot be easily and safely cut to different dimensions. The glass will rest on ½” diameter stove gasket. Rivet the gasket inside of the frame on the top of the box (see Figure 5. SOMETHING below).

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Lower the glass into the frame and slide it upwards so that its upper edge hits the middle of each hinge. Use high-strength epoxy glue that works on glass and metal surfaces to glue the hinges to the outside of the glass. Also, glue a plastic handle to the lower edge of the glass. Allow the glue to fully dry.

Finishing Touches

Use a file and metal repair tape along any sharp edges of the oven. Set a stove thermometer on the swing in the oven’s interior so that the oven’s temperature can be monitored. Since this is a solar oven for elementary school children, a fun project is to allow the students to create magnets to decorate the outside of the box. Once the magnets are put on, the oven is ready to be tested (see Figure 5. SOMETHING below).

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Results

Testing of the solar oven solution is in progress and the results are not yet available. The oven has been able to get bred to rise but the temperature value was not recorded.

Discussion

The solar oven built for a school fits the criteria required for this project. The results of our testing are still unavailable but as soon as we get it in updates will be made.

Next Step

With the solar oven complete our next step will be to take it to Trinidad School and have the Junior Chefs use it and give us feed back so we may make any minor alterations they might have.

References

These are our references.

2011 Team

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