Solar Death Ray Cooking

Ask questions about or share pics of your latest find...

Solar Death Ray Cooking

Postby bennelson » Fri Apr 04, 2014 7:26 pm

Has anyone ever used a large fresnel lens for solar cooking?

These are the types of lenses used on school overhead projectors, or more importantly, old large screen projection TVs that are getting thrown away all the time.

I mounted a 3'x4' lens in a wood frame, and on a sunny day, I can melt pennies with it. No joke.

I'm wondering about using one to heat cast iron for cooking. Just focus the lens to the size of the pot or pan, instead of a penny-melting pin-point.

Anyone ever do this before? (We haven't had a sunny spring day yet since I've started wondering.)

-Ben

Image
still no idea what i'm doing...
User avatar
bennelson
Teardrop Master
 
Posts: 137
Images: 53
Joined: Sun May 01, 2005 5:49 pm
Location: Oconomowoc, Wisconsin, USA

Re: Solar Death Ray Cooking

Postby KennethW » Fri Apr 04, 2014 8:16 pm

The bad thing about a solar reflector or lens is the sun moves in the sky. If you forget about it, it will burn or melt stuff you don't want burned or melted.
KennethW
500 Club
 
Posts: 959
Images: 80
Joined: Wed Feb 20, 2013 8:01 pm

Re: Solar Death Ray Cooking

Postby warnmar10 » Sun Apr 06, 2014 8:56 pm

I haven't tried cooking with one but I have confirmed their efficacy for wanton, gratuitous destruction.
"When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him." - Jonathan Swift
User avatar
warnmar10
Teardrop Master
 
Posts: 144
Joined: Wed May 12, 2010 9:06 pm
Top

Re: Solar Death Ray Cooking

Postby bobhenry » Mon Apr 07, 2014 6:47 am

I was fiddeling with mine and focused it on a small section of back door trim and in a blink it was smoking.

I now have my projection tv fresnel lense mounted in a wood frame and plan on using it to evaporate gray water from my tiny house. I am looking for one of those old cast iron rendering pots ( witches caldron) to drain the gray water into then focus the beam to evaporate the liquids.
Growing older but not up !
User avatar
bobhenry
9000 Club
9000 Club
 
Posts: 9878
Images: 2280
Joined: Fri Feb 09, 2007 7:49 am
Location: INDIANA, LINDEN
Top

Re: Solar Death Ray Cooking

Postby Vedette » Wed Apr 09, 2014 10:40 am

Bob
No septic sewer system or septic tank where you live? :thinking:
Good Roads
Brian & Sandi
Good Roads
Brian & Sandi
Here is a link to my Build Journal
viewtopic.php?f=50&t=50912
Image109106109111109110138766
User avatar
Vedette
Silver Donating Member
 
Posts: 5054
Images: 443
Joined: Thu Dec 01, 2011 4:28 am
Location: Westbank B.C.
Top

Re: Solar Death Ray Cooking

Postby bobhenry » Wed Apr 09, 2014 10:57 am

We were on Google earth yesterday looking at older aerial shots of the new property trying to determine where the septic field and the well may have been located. In the older pics it appears to have a small building on one side of the property I am guessing it to be a pump house and the opposite corner was a really nice green spot. As we all know "the grass is greener over the septic tank" according to Erma Bombeck. So until I locate them I guess my answer is NO at least not yet.
Growing older but not up !
User avatar
bobhenry
9000 Club
9000 Club
 
Posts: 9878
Images: 2280
Joined: Fri Feb 09, 2007 7:49 am
Location: INDIANA, LINDEN
Top

Re: Solar Death Ray Cooking

Postby GuitarPhotog » Wed Apr 09, 2014 1:37 pm

Bob Henry, how are you going to keep the lens focused on the gray water pot as the sun moves? Manually?

<Chas>
:beer:
GuitarPhotog
Silver Donating Member
 
Posts: 1668
Images: 55
Joined: Tue Feb 08, 2011 12:52 pm
Location: Grants Pass Oregon
Top

Re: Solar Death Ray Cooking

Postby bobhenry » Fri Apr 11, 2014 8:18 am

GuitarPhotog wrote:Bob Henry, how are you going to keep the lens focused on the gray water pot as the sun moves? Manually?

<Chas>
:beer:


For the short term as an experiment it wil be stationary and only moved manually being careful that the beam can not focus on any combustable surface.

I have been looking at a somewhat Rube Goldberg contraption that powers a 12 volt car window regulator. There are 2 very small photo voltaic cells that power it right and left. and a shade guard that doesn't allow the sun to shine on either if in direct alignment with the sun.
Growing older but not up !
User avatar
bobhenry
9000 Club
9000 Club
 
Posts: 9878
Images: 2280
Joined: Fri Feb 09, 2007 7:49 am
Location: INDIANA, LINDEN
Top

Re: Solar Death Ray Cooking

Postby GuitarPhotog » Fri Apr 11, 2014 1:10 pm

Bob, for a sun tracker, it's easier to use 2 photo cells with a divider between that is tall enough to shade one of the cells as the sun moves. Then the tracker moves the assembly until both cells are illuminated equally. We used this method on a solar project in college (many years ago) and it worked well with fewer parts. You just wire it up so the motor drives in the direction of the cell with the higher output (i.e., no shadow).

<Chas>
:beer:
GuitarPhotog
Silver Donating Member
 
Posts: 1668
Images: 55
Joined: Tue Feb 08, 2011 12:52 pm
Location: Grants Pass Oregon
Top


Return to Cast Iron

Who is online

Users browsing this forum: No registered users and 1 guest