One last note - As a teacher, thanks so much for including your initial failure, with this project. It's great to be able to show students an example of how we shouldn't always see failures in a negative light, but rather, as learning experiences. It speaks highly of you to have included yours.

You should be able to buy a roll of mylar from a hydroponic shop, their used in grow rooms, and won't have creases!

What's pretty neat about aluminized parabolic reflectors, and "funnel" style solar ovens, is that they can also be used to cool objects as well at night , by radiating the IR energy up into space. Make a container that is very well insulated in relation to conduction and convection, but very transparent to IR, find a part of your yard with a clear shot to the sky, point the reflector straight up and especially on cloudless, dry nights, over night, the contents inside the container will significantly cool in relation to ambient air temps.

An idea that I have been wanting to try is to use a discarded DishTV antenna. Use the same "Space Blanket" foil to glue to the antenna. The antenna is an accurate section of a parabola with off-axis focusing.

I like that you showed what didn't work and used whatever was available to keep going

Very nicely done, and thank you for making a well-organized video that didn't take five times longer than it needed to, like most KZfaqrs seem to do!

it was a true pleasure to hear you speak, and watch you work.

Nice work. Space blankets are quite transmissive, and wear very easily. I've used hydroponic mylar for parabolic troughs in the past, it's significantly more reflective, thicker, just as cheap, and a little more durable tho still not enough to just leave outside.

Nice! It's great to see the whole project -- including things that didn't work.

I love how you uses smoke to show the light! Great video

This is one of the coolest DIY videos that I have seen around for creative stuff.

I was playing with these long ago. After several versions I made just two flat rings around 3 feet in diameter. I placed a tire valve into a hole drilled into the rings. Then I took a clear piece and a mirrored piece placed them together and bonded them between the rings so the valve is between the films. Then pump air inside and it inflates like a balloon. The rings keep the lens stable. This can be scaled up quite easily to make giant mirrors. If you wish to replicate this feel free to do so. You may need to add a spacer ring to allow the space for the valve.

I did a similar thing a few years ago where I stapled down the mylar with a layer of cloth over it in a circle onto a piece of plywood with a hole in it that I attached my shopvac to. Then I inflated it and applied some resin to the cloth, which stuck it to the mylar. After the resin cured in a couple of hours I just cut off the dish with some scissors. It was pretty floppy, but if I added a ring like you did I imagine it would have been fine.

DUDE - this is absolutely awesome. Best creative thinking I've seen in ages.

Neat idea! I like how you showed your various attempts and what you learned from the failures. When I was a teen, I made a solar stove from a plan I found in a book about solar energy. It consisted of cardboard panels with aluminum foil taped on, and a plywood frame to hold it all together. Certainly not the most elegant thing, but it worked pretty well and I astounded my family by cooking a hamburger with it!

Very cool! I think you might get an even better result by making the circle frame for the mirror first (ensure it is perfectly circular), then gluing the space blanket to that.

Not bad at all! I like this design better than the one where they temporarily suck the dome in from the rear, yours has a fixed focal point, which makes it better for a lot of applications. Thanks for sharing, the compressed air + fiberglass idea was brilliant!

absolutely amazing, innovative craftsmanship and video!!!!

Bought a ten pack on Amazon. I used spray adhesive and glued several gold foil space blankets to a tarp. Tried it out a couple of times and it reduced the temperature under them by 20 degrees. Great to put over your tent when you're camping in the desert. Tried them in the winter too. Hung the tarp inside of my tent by surrounding my sleeping bag. Outside temp was 21 degrees F. Temp inside the tarp 59.

Terrific video! Can't wait to try out some of these fantastic DIY ideas. Thanks!

I'd love to see more of this telescope project!

This is beautiful, and a fantastic idea! As a physics teacher myself I will be sure to make one of these as demo pieces for my students. But I would also show your video so they can see the process you used and that initial failure... er... learning experience. Thanks so much!

Great demonstration on how to build your own parabolic mirror. I was considering buying one from Amazon, but not now. I really appreciate comments of failure or "this didn't work like I thought it would.." and then how you fixed it. Keep up the great discoveries for us folks out here in bleachers, watching you. Hartley (garden grove, CA)

Wow! Thank you for another well made, informative video. Just imagine the savings these mirrors make over burning fuels. Awesome!

Nice video! I was thinking it might be easier to create a high quality mirror without the fibreglass. Just create a box with a circular hole, place the film over the hole, and apply suction to the box. I know it will be more fragile, but the mirror would be near perfect. Also the focal length would be adjustable. There might be some limitations I'm not aware of, but would be interesting to compare the performance of both methods.

Sometimes I wonder if I could have done things differently. Then I remember I probably wouldn't be subscribed to this channel. What a time to be alive.

PRICELESS. Larger the radius at this curvature, the more distant the focus point. Can come in handy as alternative protection.

love your videos Years ago I had the experience of coming off an escalator and almost stumbled because my eye caught a mirror setup like yours but with two little differences that made it eye catching. One they had some surface that was a bit more mirror like so the reflection was good. Two they had not backed the mirror up with a hard surface - it was stretched taut across a ring and the space was pumped with a small bellows that caused the internal pressure to go positive and negative. So their mirror was like a fun house one - cycling between concave and convex. Very arresting image.

Such a nice project - but hearing about the "square larger in diameter" made my day :D

Great job! Thanks for including all the mistakes also.

I've always wanted to make one of those, and you came up with a good idea to form the paraboloid shape

human ingenuity is awesome, at every level, and a lot of work makes the project actually happen...

Nice, but note obvious the resulting shape should be parabolic. Due to the equilibrium between tensions (i.e. blanket and pressures), it rather be closer to a spherical shape. This explains the aberrations we see when you blow smoke at the focal point... but it's a better point because you need a good repartition to heat, e.g. water in there !

you always have amazing project man! when my situation allows me, i'm gonna become a patreon for sure!

An absolutely stunning piece of craftmanship and innovation.

Green Power Science , Dan, did a similar project years ago. A practical application is for a long distance laser communicator collector-receiver with the light sensor at the focus area. Thumbs up, nice construction methods.

I have been looking for exactly this spark of genius! Thank you so much!!!

That's really cool! How long does it take to set cardboard on fire on a sunny day?

Green power science did this many years ago. But used a garbage lid and a vacuum. It's worth a watch too. I like your design also, great work.

Excellently done. Thank you for posting!

5:40 marriage in one sentence.

To make a telescope, the parabolic curve would have to be much, much shallower to get a longer focal length. Telescopes tend to have f ratios of a minimum of about f/4, and anything up to f/12, meaning the diameter of the mirror is 1/4 or 1/12 the focal length. So for a 1 foot diameter mirror, you want a 4 foot to 12 foot focal length. The mirror shown here seems to have an f ratio of about f/1. To make a shallower curve, you could pour water into the middle of the mylar, stretched over a circular hole. Stretch the mylar out very tightly by clamping with lots of G-clamps over another material to spread the load. It is important to get the tension equal all the way around to get a symmetrical shape. You can check the focal length by shining a torch onto the mirror and trying to get the reflected image of the torch's filament or LED in focus. However, the water will probably affect the focal length, but I haven't done the calculations to work it out. I like the fibreglass idea, but you could probably bond a rigid support to the fibreglass with vertical and horizontal cross brace rib pieces similar to an aeroplane wing construction, before removing the clamps. Then bond those ribs to a solid base and cylindrical side-wall and it will be really rigid. I'm not sure how viable this mylar would be for imaging, as it looks a bit uneven and the reflections look kind of blurry when compared to a polished piece of metal or metalized glass mirror. Another method to consider is metal spinning - spin a large piece of sheet metal and bend using a tool to match a former underneath. I wonder if vacuum-forming (vac-form over a large open hole) could be used with a metal-coated plastic sheet, or maybe you could electroless-plate a normal piece of vac-formed plastic with metal? You could even ditch the vacuum and use heat to make the material sag under its own weight, or use water or sand to weigh it down.

Thank you for sharing this process. Fascinating!

Revolution! Perfect Idea for selfmade!

Oh this is awesome. Thanks NHIL for posting on my birthday too!

I think you'd get a smoother finish if you do a gel coat. Vacuum the resin to get air bubbles out. Pour resin like you did in the center but don't touch it. Let it spread thin and let it set up until hard but still a little tacky and then put some layers of fiberglass as you did. It should be super smooth.

You and people like you can solve this world's energy problems. Good work.

The light rays coming down onto that mirror in a cone shape is so beautiful.

Alternative: A "rotating liquid-metal mirror" automatically makes a perfect parabola, but only while it's spinning. If you instead spin resin (or molten glass or molten aluminum) until it hardens, you've made a smooth parabolic surface (which then must be "corrected" if necessary, polished, and possibly plated with reflective metal). You have to spin a "pan" that closely approximates the paraboloid you want (CNC cut or 3-D printed); the more it departs from perfect, the more liquid you need to cover it. (If the resin floats on water, maybe you could use a plain cylindrical vessel filled with water as the parabolic "pan".) Problems: Air currents could make the parabola slightly imperfect. When the rotation stops, centrifugal force stops, and the shape will change very slightly. Dust, etc can settle on the resin while it hardens.

make a round ring to hold the mylar down instead of just epoxy, then you can really put pressure to the mylar. Make the ring just smaller than where you glue and round the edges 2mm radius "so mylar does not tear" then run your fiberglass and fiberglass the ring to the mylar as well. Now you have the stable mirror and you do it all in one process.

Brillaint concept, insightful construction process, well produced video!

I identify with your thought process. Well conceived

A $1 space blanket... And $200 of other supplies. Jokes aside pretty cool.

This method might work for making parabolic sound collectors like you see on the sidelines at football games. Nighthawk, maybe you could make one and see how well it picks up distant sounds. Thanks for all your work!

A really beautifully made documentary!

Parabolic dish making very easy to showing.I love and thanks this video

Excellent! I'm interested in parabolics for solar heat investigations and this looks like the best construction method I've seen so far. Thanks v much. I don't know enough to understand the geometry, so do you know if your inflation shaping method could produce a parabolic trough? If the film was glued down around a long thin rectangle? Hmm, I guess you would have to shape the ends.

Wow!

Thanks for sharing your project/ideas.

Keep up the great work boss. Happy New Year!

When you look into the mylar and see your reflection, is the image crystal clear like it is in your bathroom mirror? If there's any fuzziness at all, then it really won't be suitable as a telescope mirror. Furthermore, the tolerances required for the paraboloid shape are tight in order to get a clear image. But don't despair -- there are other good uses for an approximate paraboloid -- like the solar cooker you've shown. I know that -- in theory -- rotating a shallow dish of liquid will generate a parabolic shape, but the liquid needs to have viscosity high enough to damp out waves and turbulence, and you'd probably need to run it for a while until the final shape is stable. I wondered if a long-curing syrup-like 2-part epoxy, rotating in a shallow dish would solidify into a nice parabolic shape. This could then be used to (1) make a long-distance acoustic spying device or (2) serve as a template for making parabolic surfaces via vacuum forming hot thin plastic sheet.

You're a fan of GreenPowerScience? Love your customization of these products. Some of which I've seen elsewhere and some I've seen here originally. The ones I've seen elsewhere are still cool because of the customization.

This is very cool. This at least has convinced me to try it on my own. 👏👏🤓 Really great DIY !! 👌

It is interesting. Excellent method! Thanks

Awesome idea! I suspect matemaematically this should be a catenary, not an exact parabola, but it burns cardboard, so it is close enough! What if you sucked the air out instead of inflating it? I mean, with the circle already in place and closed from the bottom.

Very easy to make, and it packs some heat! :-) I have to say, the audio quality of your videos is outstanding. I need to look for better audio recording equipment.

Thanks for showing this!

awesome transparency in you stating how much Rayton/CrowdfundX paid you! Very admirable!

My thought would be to make it as a vacuum system -- build the frame, seal it up, add mylar, then pull a vacuum to get an adjustable focal length. The pressure would keep the shape.

I know this is a very old vid, but this is a thought experiment I run in my head, ad infinitum: How to make a big mirror for a Dobsonian telescope. There was an article in Popular Science, I believe, which had a great method -- basically a 15"-20" bowl, on an old record turntable with the central spindle removed, filled with very slow setting epoxy. And set the whole thing up on some foam in a place far from traffic or other vibrations. It creates a parabolic surface, the focal distance determined by the RPMs of the turntable. But you still have to send out for silvering. I love to think on ways to achieve such a surface myself. This is a clever solution, I wonder how I could manipulate a space blanket to work with an existing parabolic form?

Wow, that's amazing and fun to watch!

Dude you got me hooked with starlight.... now this? Amazing👍👍👍👍👍

Spinning a fluid or liquid in a round flat container will cause the liquid or fluid to form a Parabolic shape If you use resin once it hardens you have a perfect Parabolic shape or you can use large amount of mercury to make a telescope mirror as long as you keep it spinning. I have used this in making telescope mirrors in a glass furnace to cut down the grinding of mirror for telescopes.

Hmm, wouldn't inflation create something approaching a spherical shape rather than parabolic? Obviously not in this case but I would love to know why. Also, if this is anything like using gravity to make a parabola what it actually makes is a catenary which would be fine for solar but probs wouldn't work for telescopes.

Incredibly powerful for such a small piece.

Great job man, very inspiring, thanks a lot!

Interesting. I was thinking of using a space blanket for a box solar oven. Looks like it will work.

I've made a parabolic solar reflector. Just uploaded the video on KZfaq. thank you

Wow, Super!! Smart moves! Trial and error with the right state of mind

Dude, yes! Thank you for sharing.

What if you used the dish from a satellite tv antenna? It would make a nice rigid form too. Aren't satellite dishes true parabolas? I could be wrong about that though.

Have you gotten anywhere with the use of one as a telescope mirror? That will be tougher of course, but this is seriously interesting. I've made a number of mirros for telescopes and there are some very different designs, like spherical mirros that are pulled into a parabola with a bolt on the bottom. Anyhow, good luck, and I'll be checking back to see your progress. In the meantime think relatively large in diameter, and short in focal length. Both will make for a mirror that doesn't need quite as high quality.

Really liked the concept and effort

I'M Very impressed cant wait for a telescope video!

5:00 Feels like those Ohm's eyes from Nausicaä of the Valley of the Wind...

And the neighbors say: NightHawk is signaling his mother ship again.

That is such a great idea on how to make your own large parabolic mirrors! I would like to see this applied to a solar powered wood gas generator, for people who live in the desert.

You are amazing brother. My highest respect!

“A weight from my work bench” *slaps a brake drum on top of it* 😂

Time to get six of these, an old crt screen and do some careful math and finally build that heat/death ray I've been wanting to take over the world

Using a high density closed cell polyurethane pour foam works great for me too. Doesn't require any extra reinforcement.

Great job, indeed!!! Cogratulations.

The Brain: "I shall make one the size of the moon & finally conquer Earth!" Pinky: "I'm hungry & we're out of cheese."

Two things, 1) I have used a solar blanket to shield the sun from south- facing apartments that were experiencing oven- like temperatures unless the air conditioning was on continuously. When stretched tightly over the window, you could see outside perfectly like through mirrored sunglasses. The Mylar film was allowing about 30% of the light through, not the best thing for solar concentration, but I am impressed how it does work in your video. Thin aluminum foil reflects 100% of the light... Could this idea be revisited using this instead? Where can you get a wide enough roll? With the same bonding process to fiberglass, the fragile foil would become a strong structure. 2) With this process, the shape created would not be a parabola, it would be more like the a section of the edge of a balloon, spherical in shape, good enough for the purpose, but less than perfect. Try as you might, but I doubt you get an optical surface that would work for a telescope... What DID work was a spinning dish with reflective mercury placed in it, the liquid automatically forms a perfect parabola, whose curve depends on the speed at which it is spun, but it is obviously constrained to only being able to point straight up... Hmmm, any way this could be used with an epoxy type liquid that is spun until it sets?

You certainly fired my imagination awesome demonstration thanks!

Great video. Very clever and resourceful design and execution.

Next video - make it heat water in copper pipes and make it rotating, to falllow the sun with arduino.

Nice I've used this polyester to reflect sunlight off of windows for years I knew this material was good thank you thank you thank you

If you just need a quick parabolic mirror you can ge a much smoother surface by laying the mylar on a bucket of any sort that is air tight and apply a vacuum you can even use the pressure to adjust the focus

Thank you for a most interesting video! However: by this method, in 3-D mathematical terms of space geometry, will the outcome be a paraboloid, or rather part of a sphere? Have you compared the longitudinal section to the contours of a parabola cut out of cardboard, to see whether the surface aligns with the mathematical ideal?