Saturday, May 30, 2009

Mária Telkes (1900 - 1995)

Frome Wiki -

Mária Telkes was a Hungarian-American scientist and inventor who worked on solar energy technologies. Her work on solar cooking starting in 1959 made her probably the first person to create a practical oven for serious daily use. Reflectors popularly known as the Telkes design which was one of the best in the series and could develop a temperature of 225° C. , 437° F. The box was a rectangular double-walled insulated box with a door on each side. The box had double glazing fixed at the top, and the there were four main reflectors set at an angle of 60° to the horizontal. The corner spaces between these main reflectors were fitted with four triangular mirrors. The insulated box had a cradle frame to hold the cooking vessel and to assist in tilting. The whole cooker was mounted on to an "A" type frame.

Friday, May 29, 2009

More Drawings

Interior shell with 5" insulation space.

There will be two of these folding side panels with triangles mounted with piano hinges.
The long tab running along the bottom fits into a slot running around the glass cover.

The crossing lines in the rectangles , are slight bends that sheet metal workers put to flat panels to make them stiff. Again, the flanges running along one edge are inserted into a slot running around the outside edge of the glass cover.

Detail of the slot to accept the reflector flanges. Crude drawing.

A gimble rack for the bottom of the oven.

Thursday, May 28, 2009

The Forkner Fresnel Focuser Moves to the Garden

I finished the fork today. This will always be outside :

There are 2 other parts that can be taken inside and stored when not in use, here they are , mounted on the fork :

We are going to have a lot of fun with this device. If I can figure out how to not blind people who stand near it. But that is why I built it , control rods are the next step with the Sun shining . Then a small copper boiler to make steam , and a whistle that goes off at noon. Remember, it's 650 degrees somewhere on the top of that little aluminium table. It ain't Farrington Daniels , but it sure is fun. My mother's garden is the coolest place in West Texas right now, That spot has always rolled around , and we won't have it long, but right now, right here, we got our hands around it.

Shop painting almost done -

Tuesday, May 26, 2009

A Clean Shop & the FF Focuser

I helped the " Twisters " clean the shop this weekend. It was a busy spring with long hours for all, and the place was a wreck. But this weekend marked a change, we added a "Wood Wing" , and we made room for Tony's Sheet Metal Break, to be brought over from the old neon shop. We set it up so we can paint the ole girl, without much trouble. All the metal tools have room to work around them now. I made a classic out feed bench for a great old cast iron saw we have. One more bench for the wood miter saw to finish, and we can start this project in a greatly expanded shop with far more capabilities than we had last week. I will be setting up a fixed camera position of these 2 benches, Hoping to make a time lapse of this oven.

The Forkner Fresnel Focuser

The Forkner Fresnel Focuser ....... My other Solar Project, the one I'm not begging for on the internnet.

This thing has no point whatsoever, except to show people how hot a little sunshine can get.

Lot's of big changes on Buddy Holly Ave. I stood my focuser out in the garden tonight . And damn it I forgot my camera. Where I have it now, is the wrong spot . We will move it's 09' location farther to the east, right next to the cement foot print. A little bond-dough work and some paint, & field testing can begin. We have a lead "pipe part" off a big ass organ , I want to make steam in a small copper boiler on the focuser, and see if we can make the old organ part " whistle".

As a life long student of just what the Sun can do. When the chance came to buy a 22" Fresnel Lenses on eBay at 2 A.M. , I bite hard. This lenses takes just the sun light from a 22" inch circle, and focuses it into a 1/2 inch rectangle. That rectangle is nearly 700 degrees.

We need a sundial.

Saturday, May 23, 2009

The Outer Shell

Friday, May 22, 2009


I am at a loss for words, a rare event folks , enjoy it while you can. As things stand today, after we get the shop cleaned up , we can make a start on the oven this coming week. I set a goal of raising $500 online to defray the cost of this oven. Today that fund has $610 in it.

And that's a good thing, because the $491 roll of reflective film is on a UPS truck coming from Colorado. Still hashing out the steel materials list for the frame, but that is about the last major expense left, everything else has been bought, and paid for. When that is complete , I'll post the whole list and costs here.

To everyone who has helped me with this project, my sincere thanks.

Up Date Sat. Morning
Got the steel list done, and fiddled with the size of the oven to use my materials more efficiently when we start doing the layout. I also forgot to mention the glazing, I will order that when the oven shell nears completion.

In an effort to hold down the number of posts , and to try and make this site more useful, I am adding comments, drawings, and pictures to older posts . I have added drawings and measurements to the post on the frame for example. As the shell construction moves along I will be adding to that post, and so on.

Once again , to all who got in this canoe, and took up a paddle, many thanks.

Colorado Bob

Thursday, May 21, 2009

The Under Carriage

Steel for frame :
1 - 20 ft 3/4 square tube
1 - 20 ft 3/4 - 1/8 angle
1 - 48 in 1/2 round rod - axel

Sketch - Up doodles -

Wednesday, May 20, 2009

Gathering the Materials

As I said in the side bar, I read "Direct Use of the Sun's Energy " a while ago. So this hunt for materials on the net was pretty fun. I bought a couple of real solar age products for it. My first was the reflector film , still hard to find small amounts from these guys who make and sell it. But the upside I bought it at $3.00 a foot, 94% reflective from a company who has just run a series of tests with the National Renewable Lab in Colorado. This outfit is called : ReflecTech, Inc. ( Warning their site is under attack! )
They mail out samples free, and their minimum is 150 sq. ft. As it stands now my machine will need roughly 60 sq feet of that . So the 150 sq. ft. buy breaks roughly into 3 machines. This is good news. Because , I have just ordered the rest of the stuff I need online. That being the wheels.

The other solar age material I bought was this stuff :

The Prodex and steel sheet.

The outer shell of the oven will have this next to it. Then a dead air space, then 4 inches of some old insulation; rockwool board insulation.

I'm building a pizza oven, that weighs like a box kite.

These two materials will give me something like an R - 40 wall under 6 inches thick. And it won't weigh anything. I will be getting the piano hinges from ebay when the time comes. I've got a feel for that cost. Taking in all the research to date. This oven isn't going to cost more than $700.00 in materials.

So here is my latest projection tonight -

A 15 cu. foot oven on wheels , that works when the sun shines. That 2 guys can pick-up , and load into a pickup.

Friday, May 15, 2009

The Drawings

I'm using Google Sketch - Up to do these , it's my first real foray into Sketch - Up.

This image shows part of the Reflector Shroud missing. The total area of reflector surface on this oven will be around 49 3/4 sq. ft.

I'm using a design called the 60/40 that Ken in Canada has supplied to me. My plan is double the size of Ken's oven, and construct it from 26 ga sheet metal. Here's Ken setting up his oven on a winter's day :

What This Is

For 40 years the concept of solar ovens has rotated around the idea of bringing relief to a charcoal starved 3rd world. I read "Direct Use of the Sun's Energy" by Farrington Daniels in 1973. And it was 10 years old when I found it. It's the bible of solar power. Nothing has changed about the things Daniels laid out. Nothing. Materials science developed since 1964, but the things Daniels states about the sun, and the problems of capturing, and using that stored energy, it haven't changed a bit.

But back to the ovens. This spring I planted a lot of sweet corn with the idea I would cook it , and sell it on a stick. Always with the idea of using solar power to do it. So, I went looking for the state of the art in solar ovens. It's still stuck on all those charcoal burners in the 3rd world.

Which is to say , " How do we make a solar oven from cardboard, and tin foil, and heat a 3 qt pot ? "

I'm serious, a fellow perfected that oven . It's called the Global Sun Oven . You can buy one for $289 bucks. Your purchase sends one somewhere into the 3rd world as well. And they're great, but I can't cook 100 ears of corn on one, all at one time. Which made me think , neither can someone in the 3rd world. No one has designed , and built a small solar oven like a backyard grill. With wheels on one end, and handles on the other, about 4 feet long.

So, that's what this is, this is the building of that oven, with that goal in mind. All the designs, plans and clips will be free to anyone who can use them. Whether, it's tamales in Mexico, lamb in Mecca, or corn on Buddy Holly Ave.