Instructables
A few months ago I got into my car, and it was really hot. (over 100 degrees, I was really interested so I checked it with a thermometer)
This inspired me to build a solar oven, I mean, if my car can get that hot, just imagine if heat was actually the goal.
I built this http://www.instructables.com/id/CERC-Green-Solar-Oven/, which worked incredibly well (325 degrees F) but I feel it's severely limited by the use of tinfoil as a reflective surface.

I decided CDs would be a perfect substitute, they are more reflective, and I happen to have tons of them lying around. But my goal had never really been to create a solar oven, just to create heat from sunlight. So instead of improving my solar oven, I decided to build a parabolic solar concentrator.



Step 1: Materials

Picture of Materials
DSC00103.JPG
-Cardboard
     Corrugated is harder to cut, thin cardboard will make it more difficult to attach the mirrors*
     (I used a thin corrugated cardboard)

-Tape or Glue
     Tape will partially cover parts of the mirrors, cutting down on the actual light reflected, but it allows for the mirrors to be more easily          removed and adjusted

-CDs

-Protractor
-Ruler
-Pen/Pencil/Marker
-Scissors
-Box cutter/X-Acto Knife

*The mirrors are actually just pieces of the CDs, but it's easier to refer to them like this

Step 2: Preparing the CD Pattern

-Draw two parallel lines with the midpoint of each line touching the slightly raised inner circle of the CD
-Rotate 90 degrees, repeat.
-Connect the endpoints of the pairs of parallel lines

You should end up with 4 squares containing only reflective surface, nothing clear, a square in the middle, and some arc shaped pieces.
Only the first 4 squares are important.

This CD will become your guide for cutting multiple CDs at the same time.

 
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Thats a cool poject man right on.
Discarded steel cans would be quite reflective, and nearly immune to heat or discoloration.. as would aluminum soda cans or the inside of mylar balloons. Even the inside of modern potato (or corn) chip bags.
I tried chip bags, I think it was difficult to smooth them out, or maybe it was something about the grease (or both). I haven't tried cans though, that's something I'll check out. And I would love to see how mylar works but I'm too lazy to go and get some...
its because there bendable :D
dhendricks33 years ago
That's a brilliant idea. I should try it sometime, I have load of extra CDs that I haven't been using anymore.
kretzlord3 years ago
my 2 cents, put a Thermoelectric generator (with a black heatsink attached to one side and a shaded heatsink on the other) in the focal area. Instant heat-to-electricity conversion. possible portable camp charger?
I'd like to see someone expand on your idea by mating this with a Stirling cycle engine. I know there are large commercial versions but I haven't seen any DIY versions. I can see someone who's into camping using something like this...
Imsosickxxx3 years ago
I think this is a great idea. After I return from Iraq I am considering expanding on this idea. I figure that if you are able to attain over 300 degrees. Then by taking a small satellite dish and the small mirrors from a disco ball that I should be able to compound the intensity to an exceptional degree...any words of advice or problems you ran into?
Magnelectrostatic (author)  Imsosickxxx3 years ago
Actually, the 300 degrees was obtained from an oven I built based on this http://www.instructables.com/id/CERC-Green-Solar-Oven/
I decided to build the concentrator because it's much easier to expand upon, hopefully will obtain higher temperatures and take less room, and won't catch on fire over 451 degrees F.
And to be honest I got distracted with other projects after finishing this instructable (so I haven't obtained particularly high temperatures), but I plan to go back to this and make it larger.

I had some slight alignment problems, but the use of a satellite dish should fix that. All I can think of is that if the center mirror is slightly off, the other mirrors may not be correctly aligned. I think the light would still focus, but the focus would move.
Good luck!
And make sure to say how it goes, those sound like great materials for this.
Awesome!
Voted for you on the competition. Best luck!
Magnelectrostatic (author)  FennecCooper3 years ago
Thanks!
mgimbel3 years ago
you should have made a true parabola. If done properly you can use tin foil pulled tightly using a vacuum to make an adustable parabola.
Magnelectrostatic (author)  mgimbel3 years ago
Yes, but, how do you do it properly?
aaires13 years ago
It would be more sustainble if you cut the round parts in triangles and join 2 triangles to make a square. xD
Magnelectrostatic (author)  aaires13 years ago
That does seem like it would use a lot more of each CD, great idea.
Alas.... I am very lazy
also the curve would be smoother
bconway13 years ago
you could cut foam with the wire. its rather fun
Magnelectrostatic (author)  bconway13 years ago
Hmmmmm, if only I had something to make out of foam
Dollar Tree stores has Foam Board panels in the 18"X24" range (guessing on the size).
They are just right for making poster signs,etc. And from the looks of your project, would be the PERFECT mounting structure.

Excellent Instructable, THANKS!
That's a pretty great idea, and cutting (I think) would be a lot faster.
I may try this eventually....
thank you!
lemonie3 years ago

There's some nice work here, but what is this business about "Well really there's not much I can tell anyone online without getting raped? is there"?

L
Magnelectrostatic (author)  lemonie3 years ago
I know this isn't 4Chan or anything like that, but it is still the internet. Gotta be careful out here.
I believe s/he meant, "why did you make this offensive comment?".

It does not belong on instructables.
And, thank you.
ramses3 years ago
I would have bought that windows 2000 professional disk (with license) for like $20.
maewert3 years ago
Very nice 'ible.  As a kid (before there were CDs) I made a four foot diameter cooker using somewhat similar techniques.  I made a parabolic curve template and cut  cardboard vanes which met in the center which I attached to 1/4 inch think plywood panel.  To these vanes I glued aluminum foil (I can't recall what I used as backing on the foil, maybe duct tape) to the vanes.  The thing was a bit heavy for me and before I used it the first time I moved it into position and I backed away still facing the parabolic surface and said 'Whew" just as my mouth and ears were at the center of the parabola :-)  My quiet 'Whew" echoed back into my ears very loudly.  I had fun with this before ever collecting sunlight!  I think the parents destroyed it thinking it trash.  I never did actually bake anything with it.  You bring back great memories though.
Best Wishes.
I'm not sure how reflective CDs are, but you might be underestimating kitchen foil. It's actually very reflective, aluminium being second only to silver in wide spectrum reflectance. And maybe gold, but that's probably not very practical information.

If you really want to get this thing cranking, I'd approach your local printing company for some lithographic offset printing plates, they'll probably be scrapping several hundred of them a week, and they're pretty much pure alu, very very reflective and easy to work with. You can cut them with scissors.

Also, if you're going to be working with parabolic curves, for mercy's sake get a copy of Rhino3D or other cad package, and just print out your templates. It'll take you an hour to learn how (msg me if you have any questions), and then about two minutes to draw up any curve you want. If you're doing stuff with optics you really want this stuff precise, and sketching out curves with a slide rule is for suckers.
Reflective layer on the CD made of aluminium too.
http://www.madehow.com/Volume-1/Compact-Disc.html
Yes, but then messed with. It could well be that it's still highly reflective, but it could also be not, and your still only going to come back up to raw alu, which is what kitchen foil is to start with.
Plus there's a layer of plastic in the way.

The good thing about cds I guess is that they're nice and flat, whereas foil's a bit of a hassle to work with. I find double sided carpet tape makes a nice job of it tho, long as you aren't concaving the surface too much.
jokoh3 years ago
How many degree you get with CD ?
Very nice, this is a very brilliant contraption sir.