Introduction: What to Do With All Those AOL CD's
I wanted to do something with plastic CD's besides adding them to the land fill - My solution was to use them build 3-D geometric constructions. I describe here how I used 12 CD's to build a Dodecahedron. I also built a 32 CD trucated Icosahedron, 12 of the CD's must be cut smaller an that takes a lathe,.
Step 1: Materials and Methods
1. CDROMs are made of Lucite (acrylic)plastic
2. I connect them by gluing 1/2" sections of flexible lucite hinges purchased from Tap Plastics - $1 for a 12" hinge. 25 joints are needed so you need at least 2 hinges.
3. The glue I used is "WELDON #16 clear, thickened cement for acrylic" Also purchsed at Tap.
4. A single dodecahedron "ball" is constructed in 2 halve of 6 CD's each using a layout jig I will describe.
Step 2: The Gluing Jig
The basic idea for each half, is to place a single CD in the center surrounded by 5 others so that the hinges can be glued accurately and simply. I used 6 "pegs" on a 2' by 2' piece of plastic or plywood. Drill a 3/8" hole in the center and 5 others at exactly 72 degrees apart and 4 13/16" from the center. The CD center diameter is 9/16". This is not a common size so my solution was to make the center pegs from 3/8" dowel with 3/8" ID clear Tygon tubing slipped over it. You can get both at any hardware store. I use a CAD program to lay it out, but you can also construct it on paper with a compass and protractor. Accuracy is important!
Step 3: The Connectors
As I mentioned, the connectors are 1/2" pieces of flexible acrylic hinge. I cut them using a small hobbyist saw and miter box.
1. Place the hinge in the miter box and make a firm but shallow cut at 1/2" increments. It is not necessary to cut all the way through.
2. Using a pair of pliers, you can break the 1/2" piece off the longer length of hinge.
3. Note, after snapping, the hinge will not not separate completely because the center is flexible (what we want). Use a scissors and cut it free as shown.
Step 4: Gluing on the Connectors
1. Place 6 CD's on the jig as show above.
2. Using a fine tipped permanent marker, draw a short line at each 72 degree position around the edge of all the CD's. You will need this to line up the hinges and especially the final gluing.
3. Glue the 5 hinges on the center CD and connect to the surrounding CD's - see photo.
4. Glue 2 more hinges on each CD as shown in the 2nd photo. NOTE: only add the hinges shown.
Step 5: Assemble Half the Dodecahedron
1. When the 6 CD assembly previously done is dry ( ~15 minutes) remove it from the jig.
2. Assembly Jig - this is a scrap piece of 4x4 that is 4 1/4" long with a 3/8" hole drilled in one end. Remove one of the dowels/tubing from the gluing jig and place it in this hole.
3. Take the 6 CD assemply and place it over the new jig so the the center CD fits over the peg on the 4x4.
4. The outer CDs should hang down so that they just touch where the unmatched hinges meet.
5. Glue the remaining half hinge on each CD to it neighbor. Use the line drawn with the permanent marker to get the positioning correct. This is a bit tricky, so be patient
6. You are done with half the project.
7. Make the other half with another 6 CD's
NOTE!!! The 2 halves are not exactly the same. Recall that the hinge positions marked in reg shown in the second picture were not used in the first half. In the second half, glue a hinge there and NOT in the position to the right ( see previous section ).
Step 6: Final Assembly
1. Assuming you have the 2 halves done place them together to make the sphere.
2. Remember that there are 5 matching hinges on each ( 10 total ) that should each match up to one the the lines previously drawn on all the CD's.
3. If each half has a hinge at the same mating position there is a problem. See step 5.
4. Gluing is tricky - carefully work your way around the perimeter, making sure to press each glue joint firmly and wait for it to dry before moving on the next one.
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