Tuesday, September 6, 2011

JAJFLC

Yesterday I finally got the sun to try out the JAJFLC or John And Julianne's Fresnel Lenses Cooker, but the focus point John had built in caused it to cook very slowly. Matter of fact it would have probably taken hours to cook the 4 hot dogs it was setup for because the area just wasn't hot enough. Of course the wind blowing across the hot dogs probably didn't help any. I jury rigged my rack so that I could cook one hot dog at a time by cutting it in half and placing the two pieces side by side. Still took about 45 minutes to cook me two hot dogs.

Cooking two haves of a dog here. While I was doing this yesterday a large fly decided to sample the dogs. It never had a chance to tough down before it decided that wasn't the place to be. I almost had fried fly to go with my dogs.
Melting the cheese here. Didn't take long.

This morning I modifies the design a little and it took about 12 minutes each to do a full hot dog cut in half and I had two hot dogs for lunch again. I cooked and ate the first one while the second one was cooking. It got a little too well done on one side, but I like them like that. The second one I brought in to eat and then fired up this computer to check email and forgot about the cooker until I started to smell wood smoke. The sun had shifted enough in that short time to where the focus was starting to hit the wooden frame and it was close to igniting the wood by the time I got back out there to stop the process. Whew! Needless to say the lens is covered again now. While I was trying to get the right focus for cooking I threw the t-shirt across the rack so I could get an idea of how big the focus area was. At that time it was almost at full focus and it instantly burned a hole in the shirt before I could get it off.

Looks like using the laser at the party was really the only way to fly though because in the time it would have taken to cook all the hot dogs that were eaten at the party there would have still been a line of people standing out there waiting on their first hot dog. I don't see a future for cookers this small to be used to cook large quantities of food, but its fun to play with and cooking for a couple or three people could be done. If the lenses were about 4 times as large then it might have a future at a party. I had a chance to get a lense that large someone had left at the legion some time back, but at the time I didn't snap to how it could be used and by the time I did someone else had already gotten it. :(

Those type lenses are used in the old rear projection TVs so if you see one setting by the curb to be hauled off it would be well worth the effort to remove the lens!

Update
More pictures of tried modifications. I think its where it will stay and no more modifications.
I made sort of a solar oven type deal out of aluminum foil and connected it to the under side of the grill to reflect any night not blocked by the hot dogs back to the underside of the dogs. I crinkled the foil so it would give wider dispersion of the light.
Then I used a Pyrex pie dish I had laying around to cover the dogs.
I'd moved the rack up and to a position that would allow the 4 half dogs to be covered with the light and tried this out on my last two hot dogs. Thanks goodness because I'm burned out on hot dogs after eating two a day for the last 4 days!

The focused light would have been a little cooler than on the other experiment yesterday, but the dogs still took about 20 minutes to cook. Perhaps they would have cooked quicker, but the hot dogs kept steaming and fogging up the bottom of the dish. At any rate I'm finished modifying the cooker and am calling it finished.


 

29 comments:

  1. I am gonna stop by when I have the chance , and check out yer lense , again I wish I could have been there for the part but life here is just one big party anyway right?

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  2. Can that be used to heat water?

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  3. Abby, I saw a video somewhere where one was used to heat water and did it pretty quick, But! it was in a clear thermos bottle with stainless steel wool inside it. The light heated the steel wool and that's what heated the water. Otherwise the light goes through the water and doesn't heat it. Also the reason the thermos was used was to keep the outside wind and temp from cooling the water off faster than the light could heat it. It did bring it to a boil pretty darned quick.

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  4. I'm thinking that maybe a covered Dutch Oven might work. Those things heat up pretty evenly, and should distribute the concentrated heat to the food inside in a more predictable way. Interesting project, though.

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  5. Allen, no doubt a cast iron something would help, but the area of heat is so small that the rest of the vessel that isn't being heated radiates off the heat from that one spot. It would have to be well insulated to keep that from happening. I'd imagine 4 full length hot dogs could be cooked at one time if they were placed in a well insulated dark metal dish of come kind and had a smooth glass lid over it to keep the ambient temperature from keeping them cooled off while they were trying to be cooked plus letting the light through to heat them and the dish.

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  6. My original idea was to use the lens to heat a (not terribly large) piece of steel, then set a rack over the steel for the hot dogs to be cooked by the heat radiating up off the steel. I think this would make a great pre-warmer for a solar oven with something inside to trap the heat. Get the solar oven up to temperature quickly then just use the regular collector area of the oven keep the temp during cooking.

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  7. Sounds like a pretty good idea to me Julianne.

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  8. Sooner or later you'll have it fine tuned! Then it will be time for another party!

    Maybe steak the next time!

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  9. Cool, David - thanks for the detailed info :)

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  10. HJ, maybe a party of 2. ;)

    Dani, looks like JW is going for the big guns with a 49" lens. You should be able to cook a whole meal with that sucker and maybe even roast dogs for a small party.

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  11. When I'm hungry I don't want to watch food cook for an hour! That just makes me more hungry which means having to cook more... which means waiting even longer for the extra food to cook.

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  12. I think trying to cook the dogs by directly shining it on them is not going to produce the best dog. if you focus the light, the outside will burn before the inside cooks, back the lens off and it is just a slow bright light. I think a square cast iron griddle placed inside a box with a glass lid. inside of the box will also need to be lined with steel. then focus one or two of those suckers on the griddle and the rest will heat up. apply dogs near the hot spot and close the lid (tempered glass)

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  13. austinmod, I made yet another modification to the cooker today and made it worse so had to add some blocks to get the grill at the proper height that I want for cooking two dogs at one time. Tomorrow I'll redo it once more to make the platform and sliders hold the grill at the position I want it. I cooked two more dogs with it for lunch (at one time), but it was two dogs cut in half again. Works for me though.

    It took about 20 minutes to cook them both at the same time and they came out about perfect because it took long enough for them to be heated all the way through. I like it like that so once I modify it tomorrow that will be it.

    I may see if I can find a small clear Pyrex dish big enough to fit over the cooking area (Inverted) and possibly cut a piece out of the bottom of an old cast iron skillet just big enough to fit inside the inverted dish. Maybe insulate the bottom of the cast iron and see how that works. I also have another idea and that is to put a foil covered bowl under the grill so that the high intensity light that isn't shining on the dogs will reflect back to the bottom of them. That should speed up the cooking time to and do away with having to keep turning the dogs. Just something to play with for now. ;)

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  14. It will be interesting to see what you cook up in the future. I loved the Ford Falcon Nut sign too. My first car was a Falcon, sweet little car!

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  15. that is the way to go David, disperse the light, so that the heat energy from it cooks evenly. Put nothing under the actual spot of light, let that heat up the cast iron, with the heat contained by the pyrex cover.

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  16. repsychallblues, I'm thinking of adding the earlier parabolic dish cooker experiment, a very large magnifying glass and some mirrors to make a high energy laser that can be aimed in any direction. A little fiber optics connected to a laser shotgun and I can shoot down turkey buzzards and have an instantly cooked turkey dinner. I like most old cars, but have a fondness for falcons.

    Dave, it actually works pretty well as is. One this small would never be a party cooker. Now if you want to heat up metal to cook dogs with then that will take a pretty good amount of time so its just as easy to zap the dogs as is and be done with it. Of course I have a mad scientist type mind so like to try weird stuff.

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  17. It could be with your pyrex idea. in the open, the air is taking the heat away. closed off, with the right size dish, i think you could cook 12 at a time with that thing. the ones closest to the center would probably cook first. put a small dish of water in there, maybe 1/4 cup, in a ramekin, and you could probably steam them to perfection. then put them on a very hot grill for a few seconds to blacken them.

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  18. without the grill, it would be similar to boiling them.

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  19. I think I'll just start using the propane laser again. Too many what if's floating around.

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  20. I'm finished with the cooker and have added three more pictures using foil under the grill and a Pyrex pie plate over it to cook the last two hot dogs. Good thing because I'm sick of hot dogs as of now. Still took 20 minutes to cook the two dogs, but I'm finished playing around with it. I'll probably try a small steak next?

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  21. Hi tffnguy: Thanks for all this. Got me making one of my own. I'd been wondering for a longish while what use could be made of those lenses. The only modification I'm making is that instead of the aluminum foil 'cove' underneath I'm using a stainless steel pot lid inverted dome. Gracias, J

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  22. Sofar, actually that was John and Juliann's plans for the cooker. I just kept trying to improve on it for my use. I'm sure there are a lot of other ways to improve on it, but the main problem is the sun's position in the sky. It changes the focus point in the lens and the position of the light on the grill constantly so the cooker and angle of the lens has to constantly be adjusted. Just during the 20 minutes it takes to cook the dogs I'm sure I have to make adjustments at least 5 times. Leaving it unattended is not wise at all and will probably result in a fire. To really do any good with one as far as cooking goes you'd about need a two axis sun tracking device hooked up to it. I'd suspect that could get pretty expensive, but figure JW will likely do something like that with his new 49 inch lens.

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  23. tffnguy: I'm probably wrong about this, but a simple sun tracker for such a short duration shouldn't be all that difficult and not at all expensive. Just knowing the azimuths of sunrise and sunset would give you the track to line it up, then using a spring loaded cooking timer with the set-knob drilled through for a clamp to attach to the lens and move it should give you enough accuracy for that length of time.

    But I'm probably missing something. Enjoyed the post. Thanks for elaborating. I'm trying out a different type of lens shooting for more heat. Gracias, J

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  24. Sofar, something like you speak of could be done if the focus point were larger, but you have to rotate the base and adjust the tilt both at different times or parts of the target migrate out of the beam. For this wooden monstrosity there isn't much hope as far as automating it. If I were going to go to the trouble of building some sort of tracker then I'd want a much larger lens and would build a completely new cooker on a metal swivel mount and also add the ability to change the lens angle to. Problem is that with the burn ban here I'd have to get a welding permit (Which I need to do anyway), but then I'd also need to move the shower pump to the water tank so I'd have pressurized water to spray down any fires that might start. I'd also need a spotter which I don't have most of the time when I'd need one.

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  25. Oh and I forgot to mention that the part the light hits would also have to rotate upward with the lens if it were used for early or late cooking. That could make keeping anything not solid in the cooking area tough. Matter of fact it would make it hard to keep anything in the cooking area period unless it were actually stuck to the cooking area. You'll probably see that once you start on yours. For now from about 11:30 AM to maybe 1:00 PM is cooking time and any earlier or lated puts the beam out of the target area. (With the one I'm using anyway.)

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  26. tffnguy: Thanks. I've got a couple of timers here I salvaged off old microwave ovens. I'm playing around with one of them to see if I can replace the knob with a wooden disc ground into a cam to push one end up the proper right-of-decimal degrees, if it works, I'll do the other timer similarly for below.

    Same method should work for the other axis, just changing the configuration of the cam.

    I'm just playing with it out of curiosity. Thanks for sharing your info and experience on it. Gracias, J

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  27. Sofar, you could probably use a mirror to reflect the death ray down on the target instead of raising the target with the lens. We're going to be getting in to the star wars initiative if we keep this up though.

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