Solar Design T-square for Designing Solar Cooker Reflectors


Introduction: Solar Design T-square for Designing Solar Cooker Reflectors

About: I am a stone mason. My hobby is making new solar cooking and gardening stuff. I have used solar heat to cook soil for a couple of years. In mother earth news in January, i read that their compost expert does...

I tried this on a small scale model and then scaled up.
It can better be  used on a larger scale. You could also  design flat parabolic "plates"  with mirrors  on a sheet of  plywood  to make powerful mock parabolic dishes.  (In that case only one laser shining straight down is needed)
This shows  how I used it to  design the shapes of reflectors for unattended solar cooking.
(I did not know what the  shape would be  before I began.)
The design process is done by "Claymation". Little adjustments of one area at a time until the design is complete.
The clam shape has never been repeated even though it has great potential to help people in Dafur or Haiti.
The license is attribution sharealike so  you can produce commercial versions too.



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    14 Discussions

    HI, bikerbob, the whole point of the instructable is that Parabolic dishes are pretty much useless for solar cooking and even dangerous. They are dangerous because they have a secondary focus that occurs when the sun is not shining directly on them, and that focus can be some distance away from the dish. People have accidentally burned down sheds and fences with parabolic dishes. I have seen a picture of a fence with a lovely scorch mark on it. the fence was about 15 ft from the dish and the owner was really lucky that he still had the fence. So anything you find for designing a parabolic dish is useless too. A parabolic dish needs a source of light that stays in the same place. But the sun moves across the sky and it is quite difficult to accurately track its movement. The better solution is a solar cooker that concentrates light from its path. That is what I am trying to design. is a video about the latest models.
    I think it may help people make their own. 
    The good news is that the primary reflector is pretty close to parabolic dish in shape. So it might just be that you can use a half or 1/3 section of a parabolic dish and use  the  secondary reflector to get the one hour or 2 hour cook time that you need for unattended solar cooking.    Perhaps if someone has a small parabolic dish of some kind at home, they would like to try make a model.
    A critical thing with the cheap laser pointers is getting them pointing straight down.
    They are generally not accurately pointing in the same direction as the barrel of the pointer so you have to twist them in the hole until they do!
      I only noticed that recently.  It is easy to correct IF you know it is happening.

    Just a note that I did a few simple models today. You can see them at  They are the clam shell models for 2 hour and one hour unattended solar cooking.
    I might need to find a mathematician to do calculus to solve the curves of the surfaces. My models were made with little mirrors and some are not in the same plane as the surface they are on.  That means  that if you made the shape from ordinary reflective material, it would not work exactly the same.
    So, not at the stage of making a panel cooker or dish just yet!

    I don't know where your getting the mylar but here's a little help for you since i like working rough designs in mylar. First get the 7mil its firm and more resistant to wrinkles. You can get it here.  They are reliable and friendly. You can easily fix it into shapes for things you design be aware though its not a forgiving material, thicker also makes it harder to cut. The shape you were showing is a torus, i believe you could do that with the 7mil. Its dupont mylar and very durable for this stuff at least for testing anyways. permanent is done in aluminum mirror polished sheets. If you just want a quick test get the mirror mylar from walmart camping section its used for emergency blankets. You will have to back it with something foam sheet cut to shapes you want to test. foams not expensive at about 10 dollars a 4'x8' sheet 1in thickness. Cut your pattern from poster paper first so your mylar is the correct size and shape.

    3 replies

    May I give your info to a solar cooking group?
    I am not doing anything with the tsquare right now.
    All the new info is at
    The first and 3rd diagram there are useful.
    I did a model with glass mirrors and mud and that worked superbly.
    The shape I came up with was clam shaped. (see the link)
    People would have patted me on the back if it came out like a satalite dish.
    They will have big trouble accepting "clam shaped"!
    It is what it is.
    I looked up clam shaped on google and they did use clam shaped sound stages to project the sound long distances forward in the past. (reverse of what I want).
    Sidney opera house is clam shaped, come to think of it!
    Anyway, thank you for your comments.
    Brian do you have a work around for exporting wave OBJ. from sketchup it would be very appreciated.  I presently use sketchup for my designs but if you've ever tried it you know theres no mirror ruby, no light ruby and no corrected materials reflection for light. So ive been using the shadows in reverse to track the light paths for the mirror sets. I saw your video on Art of Illusion and downloaded it to give it a try my only issue is that i will have to learn how to use yet another program. Not only that but i cant get the OBJ pluggin for sketchup to work on complex geometries. Do you have a solution?? I've tried ricks ruby from the forum but it doesnt work with complex geometries. I really want to try out my designs in Art of Illusion but each one took hours to set up and draw. The calculations take time, and then getting it just right in sketchup took time. I will let you in on something i figured out though. Use a halogen spot light 1-2 million watt they emit infra-red and the beam is extremely hot so be careful what you have at the end of the mirrors. It may catch on fire. I checked out your T square i like the idea. Your use of the drafting tools is great for checking things. It helps when you can use the 45 or 90 in a graph to visualize the outcome. I like pythagorian theorem and euclid theorems for the point to point checking. With pythagorian theorem you can easily double the triangulated point to form an equalateral triangle for the straight bounce of the light at projected angles.

    I am sorry but I cannot help you. I am rubbish with software. I put the art of illusion thing on here because I thought other people would develop it further and invent great new solar cookers.
    It did not happen.
    In fact that is most of the reason i went to the t-square thingy. 
    You might be able to get help at the "friendly skys" art of illusion forum.  They were pretty good to me for a while. And you might even be able to upload your work in sketchup and let them convert it.  The guy who made art of illusion has a relative who wrote a book about solar cooking so there is some goodwill there.
    thank you for your interest

    That's a nice rig - what did you use in the end for forming the reflector? (I had problems with the video and only watched half)


    3 replies

    Hey, Lemonie,  thank you very much for your interest.
    You kept me going.
    (I thought at this stage someone else would have ran with this thing).
    Anyway, I have not yet made a decent model but the good news is that the shapes of reflectors for unattended cooking may be quite easy to make.
    I have a horrible new video up of my first rough model. (Just for the moment).
    I have plans to replace it with a much better video.
    You need 3 cameras to do it right so I have to go borrowing cameras.
    And I also have  to wait until I get a new roll of mylar.
    I will also start a model using little mirrors stuck in clay. Not as easy to adjust but the mirrors should stay put where I put them.
    It is rewarding  to do but very sad to see such a level of disinterest.
    I think when the bugs are ironed out, it will be an awesome tool for research and education. (It is just holding the model in place that gives trouble)
    Really only you and a higher up guy at have shown any interest.
    Thanks for that..

    If I had the tools and work-space I'd be playing with these ideas, also more sun would help. I wouldn't get hung up on an apparent lack of interest, these things need to be seen by people who are interested in developing solar reflectors and there won't be many around here.


    I only did a "Mock-up" 
    I could see the basic shape forming but I could not keep everything steady enough to complete it accurately.
    Someone else can figure it out! 
    There are just so many ways of holding it together and so many different possibilities for designing the reflectors.  I am sure people will come up with several ways to complete the project.
    I might just dump the instructable  and leave people with the video.
    I failed to make the instructable clear enough.

    I put up a new video
    It is hard to watch because of jerky camera work.  BE WARNED!
    I have crappy reused mylar at the moment so reflections are not great.
    Even so, this seems to show that a 2 hour reflector may not be that difficult to make.  All you may need is one large  sheet of material (for a parabolic (ish) trough and 5 or 6 strips to redirect the parabolic trough line focus  to the cooking pot.
    I still have not figured out how to effectively keep the relfector pieces in place but it is getting better.
    So far, the jig (the t square with the laser pointers on it) are proving to be very useful indeed!

    1 reply

    (I WILL buy proper mylar and do a better model and video). 
    An interested party asked if I had made any progress so thats why the quick and dirty video is up.   The corkboard under is an improvement and I have a crude way of holding the model in place too. And I think this type of model is a lot easier to replicate than the "scallop shaped" reflector that I tried to model earlier.