In this tutorial, we will teach you the process of creating a parabolic mirror. It can be used to generate heat, for example for cooking, although this project leans towards the standards of telescopes.
Parabolic mirrors are used to focus and redirect sunlight. It would be a kind of solar thermal energy center. All with such a simple main material as thermal blanket, which can be obtained inexpensively in specialized stores.
The entire manufacturing process involves the use of compressed air to form a polyethylene terephthalate sheet (or isothermal blanket) on the dish. This is accomplished by securing this material to a flat surface that will be pressed from below like a giant cell of bubble wrap.
The first part of this project will be the surface to inflate the isothermal blanket. You start by using a PVC sheet as the material, because air does not pass through it and it is perfectly flat. Air injection will be needed from the center of the square plate you need to form.
The first step in doing this is to mount a bicycle tire inflation valve on a small piece of trim. Then, a hole is drilled in the middle of the base and with PVC cement, this cut piece which carries the valve will be glued to the stem and turned outwards.
On top of the PVC, outline the size of the mirror you want to create by tracing with a marker, then sandpaper just outside the line so the glue will stick well.
Now you take the insulated cover sheets and stretch them all over the base, but keep in mind that they are usually folded in small packages, so you have to stretch them out and remove all those marked folds.
Apply epoxy around the circle you sanded earlier and place the stretched thermal blanket over it. When it is secure, you will turn on the tire valve and start inflating the mirror. You will see how the dish forms and to keep it strong you need to apply fiberglass on top and wait for it to dry. Once you’ve done it right, apply two more coats and if desired, speed up the process using a hair dryer.
When everything is completely dry, use an angle grinder to cut the dish. Clean the result and you will see that the reflection in the isothermal blanket is very good. To keep the round shape, use some sort of tape or whatever material you have at home that is completely sturdy around the dish to create the same shape. Put a weight on it and stick it with putty.
Once it is dry you would have ready the last step to get the parabolic mirror.
If you want to see all the ingenuity applied by Ben, creators known as NightHawkInLight, you will see that before concluding that the parabolic shape can be achieved with layers of fiberglass, he tried to apply sprayed foam, but failed in the tried: