[TheForge] How to melt steel with sunlight:

[James Binnion]

Good luck with the Fresnel lenses, I think you will find it is not so easy.

On Nov 27, 2010, at 8:14 PM, Bruce Freeman wrote:

> A) We don't need no stinkin' cooking pot!
> B) That installation can get a cooking pot up to 6300*F = 6790*R =
> about 2 or 3 times any temperature a blacksmith or welder would need.
> 
> The more I think about it, the more I think that a single 11" square
> Fresnel lens would do the trick.  Combine that with Peter's idea of
> flexible mirrors, and you can probably assemble an array of 1.5 meters
> square (that's about 5' square) at small expense.  I.e, mirrors direct
> sunlight onto Fresnel lens; lens directs light to focus.  Simple.
> 
> Mount the assembly on a pivot to rotate the assembly to face the sun
> without the focus moving at all.  Once the device were set according
> to latitude, the tracking could be controlled by either a timer or by
> a very simple device that moves the assembly as the image of the sun
> through a small hole moves relative to a light sensor.  Make that a
> UV-sensor, and the tracking would work on cloudy days, albeit the lens
> would not produce nearly as much heat then as on sunny days.
> 
> One warning -- wear a welder's helmet, as the focused sunlight
> contains quite enough UV to destroy your vision if reflected into your
> eyes.
> 
> 
> 
> On Sat, Nov 27, 2010 at 10:47 PM, James Binnion <jbin at well.com> wrote:
>> You might want to look at this. It will give you an idea what size installation you would be looking at for a hot zone the size of a "cooking pot" http://en.wikipedia.org/wiki/Solar_furnace
>> 
>> 
>> 
>> On Nov 27, 2010, at 5:24 PM, peter fels & phoebe palmer wrote:
>> 
>>> Sounds even better.
>>> But we are talking about a pretty big fresnel lens then ...though i
>>> suppose a bunch of them could be used in a grid, given a bulge to mount
>>> them on.
>>> Those cheap dimestore mirror strips designed to fit on a wardrobe door,
>>> have the interesting property of bending into a mild arc,i
>>> found....which could be used as a focusing mechanism.
>>> Tempered glass will bend even further.
>>> 
>>> 
>>> On 11/27/2010 6:01 AM, Andrew Vida wrote:
>>>> 
>>>> peter fels&  phoebe palmer wrote:
>>>>> Thanks Bruce;
>>>>> That's delightful!
>>>>> Brings me back to my old proposed solar forge
>>>>> If one were to use an array of cheap mirrors with tracker/step motor
>>>>> rigs like Kurt's,
>>>>> combined with a big lens...say a pool of water in a plastic sheet hung
>>>>> from a frame.....
>>>>      Too much fuss.  Fresnel lenses can be made arbitrarily large yet remain
>>>> very light in weight.
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>> 
>> James Binnion
>> jbin at well.com
>> 
>> 
>> 
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> 
> 
> 
> -- 
> Bruce
> NJ
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James Binnion
jbin at well.com