Instructables
Turn a flat sheet of anything flexible into a parabolic reflector.
 
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Step 1: Prove it to yourself

Download this template and print it on cardstock, add something shiny cut it out and tape the edges together, don't cut all the way to the center. The template is Deltacad 6 format

Step 2: Now what?

Wel, you're done, you can print that template out any size and go to town, the plywood dish at the beginning was made that way. However if you like, in the next step i'll give you the math.

Step 3: So here's the math

Sort of, for the educated its based on the difference between the arclength integral and x, you can take it from there, for those not fond of thinking read the attached file.

Step 4: Now to build one

You could just cut one out with a jigsaw like the one at the beginning, but for better accuracy I printed out a section and made a router template

Step 5: Next I acquired the materials

I want to say I acquired all these signs LEGALLY, with permission, from the dumpster of a polling place, and I'd really like to see more instructables based on this resource, i know i'm sickened that signs are printed on a material designed to last a million years and are up an average of 2 days.

Nothing like dumpster diving in the rain

Once again these were collected legally.

Step 6: Now cut them out

quick work with a router, lots of plastic curls eveywhere, once they're cut out apply shiney aluminum tape from the hardware store.

Step 7: Now find a cool spot to work

And tape the peices together, or use cable ties, it came out a little peaked so I added a ridgid disk in the center to flatten the curve, I should have done that first.

Step 8: Finally flip it over and tada a parabolic reflector, now to turn it into a solar oven

eventually I hope to turn it into a tracking solar oven with drill head motors. a word on the coroplast plastic in these signs, to glue it u can flash it with a blow torch and use super glue, and hot glue works well to glue it together, the "rigid disk is just two pieces with the corrugations orthogonal glued with hot glue. Sorry no pix in operation, it's dark out.
ratsoso12 days ago

Just find an unused satellite dish and convert it....easy

lansry1 year ago
Get a large smooth beach ball the larger the better because the outer edges of the dish we'll make have to be cut away since they'r perpendicular to (i.e. not reflective the incoming signal. Use polyester laminating resin (fiberglass resin) and 1 or 2 layers of fiberglass cloth to cover half of it (keep it this for light weight). The focal point of the deep dishes is closer to the center than the shallow satellite dishes. This makes it less cumbersome and not as top heavy. Get some tacky adhesive (try 3M or similar) and roll strips of aluminum foil inside with a small smooth ball or 4 inch paint roller covered with a plastic bag. Focal point will be: http://www.analyzemath.com/parabola/parabola_focus.html https://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&gfns=1&q=google#sclient=psy-ab&q=focal+point+parabolic+mirror&oq=focal+point+parabo&gs_l=serp.1.1.0l3j0i20.0.0.1.126273.0.0.0.0.0.0.0.0..0.0...0.0.0..1c..17.psy-ab.-ixL3Blp4jE&pbx=1&bav=on.2,or.r_qf.&bvm=bv.48340889,d.cGE&fp=baea18be682a6c13&biw=1024&bih=679 Use the metal rod out of a lamp or other. Make a pivot out of cardboad and polyester laminating resin. Take the rod that bolts to dish and put in the center of a square of cardboard. Place pieces of cardboard to either side of it. The cardboard pieces must not be higher than it's diameter. Remove the rod and fiberglass the pieces keeping them in same position as when rod was present. Do the same for the vertical rod which will be the floor mount. Get a piece of auto inner tube or similar rubber to go between the fiberglassed cardboard. Put the two pieces together (one hole will be vertical the other horizontal). Drill a hole put a bolt with a flat washer through it, another flat washer on opposite side, then a lock nut and a wing nut to tighten it. Cut a large circular piece of plywood for the base. Glue a piece of 2" x 4" wood (or similar) to it in the center. Drill a hole in it's center the same diameter as the vertical rod which will support dish. Place weights (perhaps liquid soap bottles filled with water until you find more aesthetic) on it to prevent tipping. Use an Alfa AWUS035H wifi adapter mounted with cardboard pieces in the shape of an "L" bracket. Punch holes in the cardboard and put 2 rubber bands through to hold the adapter in place (this makes it adjustable). Tape the cardboard mount to the dish and then glue cardboard tabs to the backside to prevent it's moving. Sorry folks this is as simply as I can put it without photos. Ask your friends if they understand. Hav fun . . . digit while U can. Kiss kiss ttfn, bye now
br0dy1 year ago
An easy way to get the diagram needed to build a paraboloid from a flat sheet with different distances from the vertex to the focus http://ma.rcosbartolo.me/paraboloid
"...for the educated its based on the difference between the arclength integral and x, you can take it from there, for those not fond of thinking read the attached file."

Would it be a violation of the "be nice" Policy to tell you to flippin' piss off!!? 

Arrogant little twit. Why do people that are good at advanced math seem to think they are better than others? I learned to read at age 4 but I happen to hate math. I passed high school Algebra with a D and never looked back.  And I have done ok so far. If I wanted to be a rocket scientist I would have study rocket science. Really this is no more than the math it would take to figure out the arc of a boat deck. I've also built a 17 sided end table and covered it with 6 inch wide 1/4 inch thick mirrors without a calculator and it came out perfect. I also know a little about GPS, Grammar, Punctuation and Spelling. (subtle hint)

Does that make me "not fond of thinking"? As if I care about your opinion. I was just looking at your channel and had almost decided to follow when I read that comment. Now you can you can take a long walk off a short pier for all I care.
tstark19702 years ago
For pete sake people someone talk english here... we are not all science buffs.. just put the math on here so we know what the heck to do. It would some much easier then giving us this sight and that sight.. just tell us what the piece measures that way we all can make on and go about life. I can't open it either and I have the program for it.. SO TELL US PLEASE :o(

I convert the file to PDF format with Any DWG to PDF Converter - http://anydwg.com/dwg2pdf/

drmattyg2 years ago
I wasn't able to reproduce your math. Here's what I worked out, I'd be interested in your derivation: https://docs.google.com/document/d/19uwcK3_8pTK7NEc2ifPoZrFViOP3_v-oYplNIviHVEg/edit

Ah, I see now that you were approximating for shallow parabolas. Given the ability to use, e.g., wolframalpha.com to do complex integrals, and the fact that it has a closed form, I don't see any reason to use the approximation, but it all comes out the same in the end.
Modarius6 years ago
How come I can't open this file? I have an IMac and the parab16 wont open. also the "dxf" file shows up as a bunch of letters and numbers and lines. Please help a newbie out as I'm not good with this stuff. maybe a PDF file or something like that
Hello,I always use the dxf viewer to view dxf files. You can google it, or you can visit http://www.autodwg.com/dwg-viewer/ to download a free trial version to try.
Use Inkscape.
hi well i use Windows XP but i convert the DXF file to EPS and CorelDraw just click on donwload RAR file on this link http://vallesan.deviantart.com/art/How-to-build-a-parabolic-174064501
Here is a free online media format translator that should help: http://media-convert.com/
you need adobe illustrator
vallesan4 years ago
Hi TOOL USING ANIMAL I took you design and convert it to a Corel Draw 14 and EPS ..so anybody can download it from here : http://vallesan.deviantart.com/art/How-to-build-a-parabolic-174064501 if you don't agree let me know i will erase the file .. thx in advance ........................ Aqui esta el archivo convertido a CorelDraw14 y a Vectores en formato EPS .. por favor hay que distribuir cocinas solares para que c deje de contaminar y talar arboles : http://vallesan.deviantart.com/art/How-to-build-a-parabolic-174064501
Ardnoc4 years ago
in your example calculation I think you have the petal count and focus transposed. 

nice instructable!  using this for the mirror on a solar cooker.

Thanks
spinach_dip7 years ago
People call that stuff "street spam" and when it's not election season, it's no more illegal to harvest the neat corrugated plastic than it is to pick up litter on the side of the road (which it exactly what it is).

Yea, of course there's an exception for elected officials and those who seek public service to pollute, but you can go shopping with a clear conscious. after the election law deadline.

I've used this stuff to hold the insulation away from the under eves vents in my attic.

Here's another use:

http://www.iamanangelchaser.com/products/street_spam_lounger/street_spam_lounger.html

Thanks for the link. I love the lounger. I don't have room for it but can use it for insiration. I think this would be a great instructables challenge to start the day after the election.
A freeware program for those that haven't found a way to view and print .dxf files:

http://www.irfanview.com/

Irfanview has a Paint plug in so it's very easy to cut, paste and print sections of that paraboloid.
cactii4 years ago
 In the rain hey... That explains why all the signs are blurry. ;)
strmrnnr5 years ago
Just wondering if you have ever used this with a photovoltaic cell. What kind of an effect do you think it may have on the output of the cell? Do they have a Max. designed for standard direct sunlight? Might be able to turn a cloudy day into a sunny day, for the cell anyway. Just wondering.
I saw a video on youtube where a fresnel lens was focused on a pv cell and the cell was under water to stop it from bursting into flames.
I've never tried, but readed about photovoltaic cells. Apparently (and obviously) you'll get more energy out of it (compared to no reflector) but it will shorten the life of the cell. I haven't tried but it sounded logic to me. Instead, I plan to use a stirling engine (coupled to a dynamo), which looks to me more efficient.
matroska5 years ago
"Nothing like dumpster diving in the rain." That's a new favorite quote for me!
radon2225 years ago
If I print out this template at some other size, how would I figure out how far out the focus is? I want to make a reflector for a wifi transceiver and I need to know where to place the transciever. When I printed it out on 8.5x11" paper as large as possible using a crapy dxf viewer, I was able to get it to print it on 2 pages at 8.75" in diameter so there must be a way to calculate the focus distance from that...
strmrnnr5 years ago
Go to Wal-mart and get a couple of those full length plexi glass mirrors for $10 and cut it into 1" strips to line the inside. You'll get some reflection then.
bazalaz5 years ago
save the dxf file to your desktop then convert it to pdf using anydwg
bazalaz5 years ago
google dxf to pdf converter or go to http://anydwg.com/dxf-to-pdf-ex.html they have a free trial that will convert to pdf for acrobat reader
fishhead4556 years ago
FLATULATIONS--Not sure if you guys already know this but here

http://home.arcor.de/ernst.willand/amsi-model.html

is how I figure the curve for my trough collectors. Carefully constructed these will turn water to steam in a pipe quickly...so I use engine oil. Build a small trough and heat water quickly.
Thanks to Homohabilis for starting this thread.
I would be SERIOUSLY interested in details of how you made trough-shaped collectors. I've thought about building a heliostat (that is, a steam engine powered by solar heat) for years!
wanzewurld6 years ago
I've been thinking along these lines for a couple of weeks recently and for a few years off and on. I was wondering what I could do with an old(er) ~8 Ft. satellite dish receiver. All I could come up with as a coating was aluminum foil which would cut the efficiency down and re-mounting it on a squared "Y" mount. Then it would be a matter of clock driving the vertical main mast and rotating the dish from one side. That would give control over azimuth and altitude. I was thinking along the lines of using a cone as a pulley or belted drive which would give varying tracking to adjust for the hours of daylight and approximately the same thing to adjust for daily altitude changes on relative sun position. It seems unwieldy but should work in theory. Any feedback on this? Adding to the "heating water" and running a sterling engine I read years ago about a long parabolic reflector heating a long tube but the heat transfer liquid they used was Tung oil. I'm trying to research that but Tung trees seem to have fallen out of favor since my childhood; they grow well in this section of the country though and make beautiful shade trees. They make a sort of "Fruit" that was once the basis of almost all oil-based paints. A "nut" was a bit smaller than a tennis ball and left a bruise if you were unfortunate to be standing at the right place at the wrong time! I'll furnish an E-Mail address in the near future for anyone caring to correspond and collaborate. Wayne
paladin426 years ago
would like to apply this to my batch collector to help focus the sunlight. what angle is most effective for heating my water tank. also can i use this to possibly lengthen the amount of time in the day in which the sun will hit my collector. my thought is as the sun goes down the reflector will focus and intensify the waning sunlight. any help is greatly appreciated.
The angle is always--your latitude plus 15 degrees. (Example: if you live at 30 degrees latitude the angle will be 45 degrees).This in the correct alignment to take advantage of the planet wobble between the relative positions of the sun in summer and winter.
Sandisk1duo6 years ago
hey, that's not tape, you just blurred it out in photoshop! Great instructable though!
Tool Using Animal (author)  Sandisk1duo6 years ago
No that's tape, the blurring was because I worked for the county at the time and didn't want to get in trouble for using the political signs.
oh ok
Thank you!! I've been looking for a way to do this (easily) for three seasons now! And without figuring out the math! I'm just not built that way. There's this amazing spanish video on youtube that shows that you can cook anything in the cooker (fried, baked, boiled, canned, and even popcorn)! Enjoy: http://www.youtube.com/watch?v=9lvIJStLdYk
Hopefully I'll post my replica before September :)
wanzewurld6 years ago
I see that I seem to have an E-Mail address at this site so someone please send me something - anything so I can see if it works. I don't see any way of sending anyone else E-Mail but haven't explored my "Inbox" yet. Perhaps they have an address book there. Wayne
nuke-em6 years ago
Totally agree with macrumpton. The picture could be written in an easier format.
for mine, instead of using signs i used reflective duct tape, i don't know what it is called and i put it on my dish, one problem though is that i accidantly put more tape over a lot of spots and so now the focus point is really hard to find oh well, GREAT INSTRUCTABLE!!!!!!! thanks
I don't exactly understand the equation Can someone help me out please
The easiest think to do is download the dxf file open with a cad program, print and go from there.
ARVash7 years ago
I wonder what would happen if you put a solar panel in the middle of this XD.
depends what you mean by solar pannel, well, not really,but back to the point, you could use the solar collection to turn water into steam and drive a sterling engine to generate power....
Truik ARVash6 years ago
Most solar panels would generate more electricity but would also burn out more quickly. There are a specific solar panels especially designed to have "more than one sun" and they are meant to be set up with reflective mirrors for generating more energy but they are also more expensive. I wouldn't burn out a regular solar panel attempting to tweak more out of it with a parabolic dish. Especially this one. I'm sure it would damage it quickly.
you don't want to put a PV panel at the focus of this thing... you want to put a Stirling Engine at the focus of this thing...
It should work 'better' if you don't burn it up! Put it a little closer than the focus. I was thinking of trying to get a metal/copper plate, solder copper pipes to the back of it as a heat exchanger, and get some of the solar 'film' kind of solar cells to put on the other side of the copper plate. Now put that in the focus area, and it should heat the cells, and you can get hot water off of it too. You might try using PEX rather than a garden hose to run the water through it.
J_SCAP6 years ago
PARABILUA...... just throwin that out there
tinglystix7 years ago
How parabolic does it need to be, really? I have a 1.5 foot diameter parabolic mirror, but it's only very slightly curved. It should work except for that it would have a longer focal length, right?
I know this comment is very late but where did you get that mirror? I want a large parabolic reflector with a long focal length, and I don't want to have to build one.
I know this comment is very late

Doesn't matter, I get the email saying someone replied to one of my messages just the same as any comment. :)



where did you get that mirror?

The college I was helping out at was clearing out the junk that'd piled up in their science department, and I got to take whatever I wanted. Therefore, I made off with a Van de Graff generator, a ginormous Fresnel lens, and the aforementioned parabolic mirror.
you are right, the 'flatter' it is, the further out the focus is.
So theoretically, couldn't you cut a hole in the middle of this, add a wireless USB network adapter and pick up WiFi from forever away (sort of like the WokFiWokFi)? Incidentally, if you did that you probably wouldn't want to make the inside shiny lest you burn down your neighbors house, eh? ;-)
you know they did this on mythbusters adam and jamie used one inch mirrors on a satalite it was huge and instant flame
yeah but it was a couple thousand 1 inch mirrors
Galume7 years ago
Animal, can you please post a jpeg or pdf of the template? I plan on making a solar-powered laser (& accompanying instructable) and I need a good template for the experimental dish. I don't have an autocad programs, and the computer from which I'll be printing a large copy of the template DEFINATELY doesn't have one ;-] Thanks-
Tool Using Animal (author)  Galume7 years ago
I'll put it on the to do list, maybe this weekend
Cool...I apreciate it. :-]
Tool Using Animal (author)  Galume7 years ago
they're in step one with the other templates, 300 dpi jpegs
easycom897 years ago
I'm so glad you posted this!!!!! i have been searching for ages on how to make one of these things. I built one of these about 5 years ago and it was sweet. Thanks for posting this!!!!
HOMEPIE647 years ago
question could i use one of the parabolic shaped sleds and spray paint it silver(sterling silver spray paint) it looks affective but im not sure???
thanx
PLEAS POST PDF TEMPLATE PLEASE PLEASE
vlxwgn7 years ago
I know I could probably find a converter or a program to open those files, but could it please be possible for a jpeg of the layout?
Veovis7 years ago
HAHHA! rock on!
rhino7 years ago
I also would like to see a dxf.
And this is supposed to do what? Don't take it offensivly, i just don't get it...
You point the shiney side at the sun and anything at the focus gets VERY hot.
tescavko7 years ago
I like the idea of using that metal tape on the disk, I have been looking at the mini satellite dishes to make solar ovens, because of two reasons. 1. they have an arm extended out already that is the right length to concentrate the sun energy. 2. they come with many different types of mounting options. and i guess there are a couple more reasons. 3. they are almost available in every town. 4. they have adjustable skew plates and elevations. 5. people throw them away all the time, a good way to recycle about 15 pounds of steel or metal. Also if you have a car junkyard nearby the motors used for wipers are strong enough to move the dish, and a plus is that they are stepper motors.
static tescavko7 years ago
While some time has past since I worked on one, I'm surprised to learn that auto windshield wipers now use stepper motors. Can anyone advise the time frame this change took place? Thanks... S.
(removed by author or community request)
Here you go
I can't open either of those. I don't know what DWG is, and neither does Firefox. Firefox says the DXF file is and AutoCad file, and I have nothing that can open either file. Can you post an SVG or PNG?
static Ian017 years ago
Forgive me if I'm stating the obvious for some, but it seems many don't know about this. When you run into a file you can't open simply google the file extention. Chances are you will find a free application that will allow to both view and create files that use that extension. At the very least you (should find a free viewer/plugin that will allow you view it only. Nodays if there is an image I want to share, if I can't use the generic edit commands( control A,C,P) I simply hit PrintScreen, Open Open Office Writer, use control C to paste the clipboard contents into the document, and export as a PDF file. Using the print screen is a last result, beacause it creates an image with undeed parts. S.
takuan7 years ago
regarding the cutting of Coroplast:: This material can be cut on its corugation axis by the use of a specialized knife. It is basically a double hook blade. One hook engages the internal square tube in the the sheet as a guide whilst another hook cuts the upper surface of the sheet. It essentially uses the sheet itself as a cutting guide. I believe the manufacturer is in Quebec, Canada and markets this tool as "Plastikut" or somesuch. Enquire at your local plastic sign supply sales agent. This knife permits freehand straight cutting, slitting and various trick cuts that greatly simplify working with Coroplast..
GEOD9987 years ago
SORRY, NEW TO THIS SITE, BUT WHERE CAN I FIND THE DXF???? ID LIKE TO TRY MAKING YOUR DISH. THANX
Tool Using Animal (author)  GEOD9987 years ago
here yah go
foobear7 years ago
what did you use for the silvery side? aluminum foil?
binnie foobear7 years ago
haha to reflect light in his case, but can reflect sound and stuff better
macrumpton7 years ago
Of course we all have the deltacad 6 program... Not. How about a format like DXF or Tiff or Gif or PDF or something that other programs can read?
Tool Using Animal (author)  macrumpton7 years ago
I linked a dxf in the main comment thread
carbon7 years ago
Has no one thought to put two of them together to get holographic goodness?

http://www.optigone.com/holograms/mirage4.html

Although, we would need a better reflective thingie on the inside. Also: You can sometimes put two flashlight reflectors together to get the same effect.
randName7 years ago
Where is the focal point of the parabola?
Tool Using Animal (author)  randName7 years ago
of the one i built, or in general? The one I built, i have no idea at this point, boredom and space constraints consigned it to the landfill. In general y=x squared /4p where p= focal length.
How did you manage to cut the cooroplast strait? I'm kind of a perfectionist and like strait lines, I buy the huge 8 by 4 foot sheets at my local sighn store to make the bottoms of my dove cages but I cant seem to figure out an easy way of cuting it. The 4 mill allways seams to make my exacto knife slip over to the next bar and the 2 mill allways seams to be to too bendy and dose'nt hold its shape without creaseing. What am I doing wrong?
illuminate7 years ago
sorry I meant put one instead of puton it's like 6:30 in the morning
illuminate7 years ago
oh so you make solar ovens out of them? hmmmm...interseting maybe I could put a mirror that's reflecting most of the sunlight on the ground and puton of these things right over a metal can of liquid explosive where it would reflect a beam of sunlight right over the can and make it go boom! but I'm to lazy and probably won't do it actually I know I won't do it
tescavko7 years ago
and, yeah i install satellites for a living.
illuminate7 years ago
I dont mean to sound like a total moron and I guess I should have stayed in the explosive department but what is a parabolic reflector and a heliostat thing? thanks for the help and one more question, could it help me blow anything up? :)
Tool Using Animal (author) 7 years ago
Of course when (if) I continue the project I'll post it. The silvery stuff is two things, one half is silvered mylar tape, it tends to bubble up, the other half is shiney aluminum HVAC tape from Home Depot, it tends to wrinkle. I wanted to see which was the better choice, personally i'd go with the aluminum tape next time.
Tool Using Animal (author) 7 years ago
you're right of course, the end goal is a helistat, right now it's just a reflector
Cool! Are you planning to post the instructions for the rest of the project? I'll look forward to it...
oskay7 years ago
This looks like a parabolic solar reflector, not a heliostat.
http://en.wikipedia.org/wiki/Heliostat
spinach_dip7 years ago
add the keyword "Coroplast"