Giant Fresnel lens for 3000 degree solar welding

These are 3 1/2' x 2 1/2' in diameter. I bought one in 1988 from Edwards Scientific $140 -- haven't seen them advertized in years. Received a flyer from Electronic Goldmine (800-445-0697) today, priced at $79.95. A wood scrap will burst into flame in seconds, water will boil in seconds. Weld, braze, you name it. I've dealt with E.G. for years -- very reliable.

Bill

-- William J. Schenker, MD (wjs@linkfast.net), September 13, 1999

Answers

Hi Doc,

NOW I get it!!! :)

Do you build a frame on a swivel so you can focus/slant it as needed? (kind of like a floor mirror?). This sounds interesting... my dad had talked recently of coming up with something like this. Thanks again for the info. Also, do you still have the name and phone number for the guy who supplies custom crystals for c.b.?

:)

-- Kristi (securxsys@cs.com), September 13, 1999.

KRISTI:

You got it on the configuration of the lens stand. Your dad is a smart man; so is his daughter.

JAN CRYSTALS, 800-526-9825, M-Th 8-5 EST, F 9-3 (orders only.)

Bill

-- William J. Schenker, MD (wjs@linkfast.net), September 13, 1999.

Bill,

Very useful information! I've just sent it out to my local e-mail group.

Thanks, RUOK

-- RUOK (RUOK@yesiam.com), September 14, 1999.

What's the distance from the flat plane of the lens to the focal point, and what is the size of the focal point? (Is it really finely focused?)
My reason for asking is evidently from what you say that you could boil water in a pan with it during mid-day. But could you boil water in a flask (through the glass) to use it for distillation?

-- A (A@AisA.com), September 17, 1999.

http://www.goldmine-elec.com/ is the site. But unfortunately they haven't really "got it" about how to do an on-line catalog. After laboriously loading some .pdf pages, I found a small fresnel lens, but not the one mentioned above. However, even that one will supposedly boil water. It is on page 12 of the .pdf catalog, for $20, and is 15-1/2" dia or 10-5/8" square, with a focal length of 12.5"

-- A (A@AisA.com), September 17, 1999.

Excuse me, -- PAGE 63 -- (don't load the file with page 12, it's 800K).

-- A (A@AisA.com), September 17, 1999.

William ---- Need some help here. Just called Electric Goldmine and they do have the Frensel Lens, it is 41 inches by 31 inches. My question is, how heavy is this lens and what is it made of? Thanks

-- thinkIcan (thinkIcan@make.it), September 20, 1999.

THE FOLLOWING INFO ON THE FRESNEL YOU WON'T GET FROM EL. GOLDMINE --- THEY'RE JUST SELLING THE ITEM AS SURPLUS WITHOUT ANY DOCUMENTATION AS FAR AS I KNOW --- I GOT MY INFO FROM EDMUND SCIENTIFIC'S CATALOG 20 YEARS AGO ALONG WITH THEIR 'FUN WITH FRESNEL LENSES' BOOKLET #9053. DON'T KNOW IF BOOKLET IS STILL AVAILABLE (THEIR GIANT LENS IS NOT IN THEIR ONLINE CATALOG, JUST THE SMALLER ONES.) IT'S A GOOD LITTLE BOOKLET WORTH THE $5 I PAID FOR IT. (www.edmundscientific.com)

A (A@AisA.com:

The focal length is 40". My recollection of the focal point is that it was about several inches in diameter (or maybe smaller) -- lens is still packed away -- haven't got to it in my preps yet. And yes, one of my plans is to do just that: boil water in a flask for distillation purposes. Also maybe distill alcohol -- I want to make ethanol to use for surgical anesthesia post-y2k. Also Zoobie could use this instead of obsessing about his stash of matches. But welding is my BIG ambition with it.

THINK I CAN:

I've got it encased in a cardboard sheath -- the whole thing feels like it weighs about 5 lbs or so. It is made of clear plastic. BTW, be careful about cleaning it -- scratches easily. The Edmunds book gives details about its use and care & safety warnings about eye protectors, etc. GET THE BOOKLET if still available.

Bill

-- William J. Schenker, MD (wjs@linkfast.net), September 20, 1999.