Make a Solar Cooking Frame for Cheap (Fresnel Lens Frame)
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Make a Solar Cooking Frame for Cheap (Fresnel Lens Frame)

August 25, 2019


I’m getting a couple of wood 2x4s ready because
my 4 foot magnifying lens needs a sturdy frame. I hacked this out of an old TV in a previous
video, but it’s too flimsy to use on it’s own. We need something that’s super cheap
to make, but sturdy and easy to use, and I’ve got an idea that just might work. Measuring the sides of the lens seems like
a good place to start, so let’s do that and then mark the wood for custom cutting. It’s
best to use as little wood as possible so I’m gonna use this table saw to rip these
studs in two. This shouldn’t compromise the integrity of the frame at all, and it will
cut the weight in half! These 2×4’s are now 2×2’s, and we’ll need to cut a groove right
down the middle. Once I’ve got the center lined up, I’ll lower the blade down to about
3/4″ and get the saw spinning. As the beam glides over the blade, I’m happy to see that
it cuts a clean 3/16″ groove. This is the groove that our lens will fit into and sliding
the pieces into place proves that the cuts were good. The edges match up and the frame
looks functional, but before we secure it, we’ll need to drill some holes right in the
center to accommodate this 3″ bolt. I’ve added a rubber washer to the bolt and pushed it
through the hole, then when this piece goes back in place we can still access the threads.
Oops, I almost forgot. I wanted to add a more finished look to this frame, so I’ll add a
1/2″ chamfer bit to my router, and trim the outer edges. I built this router right into
my workbench so I’d have a lot of room for bigger projects. Look for how to build this router table in a different project. These simple cuts are quickly giving the frame a more professional
look. Ok, those are done so now I can retract my router bit and lay these support blocks
down. The lens goes overtop, and these blocks are helping prevent the lens from warping.
When we’ve got one of the corners lined up, we can drill a pilot hole, and add a 3″ wood
screw. That’s holding well, so let’s repeat that on the other 3 corners. Drilling these
holes first, helps prevent the wood from splitting when the screws go in. The Scorcher lens is
framed, and we can put that off to the side and get to work on making a collapsable “A”-frame.
This time we’ll need to cut two 5′ lengths of 2×4 and rip them into 2×2’s the same as
the others. I wanna make a hinged frame, but before we do let’s router these edges
as well, and save some of the saw dust for a future charcoal making project. Alright,
my table is clean again, and I’m gonna try an idea for a modified hinge with these
eye-screws. These screws were 6 for a buck, and we’ll only need 4. Holes are drilled in
the center of the the chamfered edge, and then these screws are tightened to where they
line up nicely with each other. They stay together closed, and fully open, so I’m hopeful
this is gonna work. It’s time to join the “A”-frame with the Scorcher lens. A washer
and nut go on the bolt, and now I’m cutting this barbed sprinkler line coupling to act
as a spacer. The barb is on, with a washer on either end, and the eye-screws are added
next, followed by washer, barb, washer, and secured in place with a wing nut. Everything
is duplicated on the other side, and these frame legs pivot just the way I was hoping.
Next we’ll need to measure the distance between the legs and cut 4 more pieces of wood to
act as support braces. When those are roughed in place, let’s measure about 10″ from the
Scorcher frame and make some marks. When we’ve drilled the holes and added the screws, the frame is pretty much done. The Scorcher lens rotates a full
360 degrees and seems relatively sturdy. One more thing I wanna try is adding an adjustable
tensioner, so I’m cutting a scrap piece of 1/8″ hardboard into a strip about 2″ wide
and 18″ long. Then I’ll adjust the saw to cut a groove in the center stopping about
1-1/2″ from the ends. A hole is drilled in the frame 10″ from the top and the band is
connected to the frame with a 3″ bolt and some wide metal washers. A wing nut will hold
that together loosely, then this other end of the strap connects to the side of the pivoting
frame about 5″ from the fulcrum. Oops, that’s a little too tight, so I’ll back it off a
touch, and give it a test. I can still rotate the lens nearly 360 degrees, but now I have
the benefit of being able to position, and tighten this securely at any angle I want.
The frame looks great and totally exceeds my expectations for functionality and practical
use. The best part is we made the whole thing custom for about $8! That’s it for now. If
you liked this project, perhaps you’ll like some of my others. Check them out at www.thekingofrandom.com

Only registered users can comment.

  1. Hey Grant, love your idea for the solar scorcher! I built one to the specs you used. Unfortunately my design has a flaw that I was wondering if you could help with.. The finished product puts out a 1"x3" beam instead of a focused dot when focused. Any idea how I could better focus that?

  2. i have always wondered why my stove seems so weak compared to this, it uses blue flame which i heard is usually 3000 degrees f so, why?

  3. I'm sure this has been suggested before, but why don't you publish a book with plans and parts lists for all your projects? I'd buy it.

  4. What table saw do you have? Looks like mine but mine makes terrible cuts. Even after hours of messing with it to get it accurate.

  5. um I got a lence and tested it how do u tell if its a crystal-clear one, how do I clean It ,and what's the length if I'm building the frame from 2by2 also can this count as arson

  6. Awesome build! Just finished one of my own the other day. The guy trimming some of our tree was impressed with it as was my neighbor when I got the scorcher out today. I directed them both to your channel to check out your other videos. Thanks for sharing!

  7. Grant posts awesome videos that I want to try but I cant, I dont have a shop at the house I moved into, (My grandmother came with us and took over the whole garage with her junk) and I'd have no where to keep all of the finished projects.

  8. that if freaking cool. i wonder if you put a couple of bricks under that slab could you cook a pizza under it ? i like green peppers, onions, and mushrooms.

  9. Do all brands of projection TVs have Fresnel lenses like the one you ended up with? Or do different brands use different types of lenses?

  10. Just used this as a template for framing my own lens. upgraded the hinge design by incorporating larger eye screws, a 5/8" carriage bolt and I used metal spacers. Took it out in the sun at 11:30 AM Pacific and instant fire as soon as I found the focal point. Thanks Grant, couldn't have done it with out you. Chris

  11. hey Grant Thompson – "The King of Random" I built the solar scorcher! Finally! It took me a long time, but i finished it. I still have yet to use it, because i have been too busy, but i am pretty excited.

  12. I assume you graduated college, Grant, since the knowledge and skill you possess is too much for someone without college education. So I must ask, what did you do in college?!

  13. I'll save the sawdust for a future charcoal making project doesn't upload the sawdust video until 3 years later

  14. Nice One Bro, You Change The Industry By Using Solar Power To Cook, Melt, Boil And Start A Fire. Thank You For The Life Hack. I Know I'm Just A Teen But I Am Gonna Make One Of This.

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