[TheForge] How to melt steel with sunlight: 2

[Bruce Freeman]

Take a big cylinder or bowl - like 6' dia, fill it with liquid and
spin it at a low speed the resulting surface will be a parabola of
rotation -- i.e., a parabolic mirror shape.  If you can get it to
freeze without significant contraction or expansion, you're most of
the way there to a parabolic mirror.  Or use a reflective liquid
(mercury comes to mind, but is too dense, expensive, and toxic to be
reasonable) and just keep spinning it !

On Mon, Nov 29, 2010 at 2:11 AM, peter fels & phoebe palmer
<artgawk at thegrid.net> wrote:
> Why polish up there Jerry. when you can just use it as a mold to cast an
> ice lens, or 7?
>
> On 11/28/2010 9:02 PM, Jerry Frost wrote:
>> I've given thought to buying an old 6' plus satellite dish and polishing it
>> but wouldn't you know by time I had room they were pretty much all gone. Oh
>> well.
>>
>> Jer
>> ----- Original Message -----
>> From: "peter fels&  phoebe palmer"<artgawk at thegrid.net>
>> To: "Blacksmithing List Sponsored by ABANA"<theforge at mailman.qth.net>
>> Sent: Friday, November 26, 2010 11:30 PM
>> Subject: Re: [TheForge] How to melt steel with sunlight: 2
>>
>>
>>> I brought the solar forge up because historically, vast forests, all
>>> across the old world,  were felled to make charcoal
>>> for metal smelting and working.
>>> It was an ecological disaster.
>>> OK..the potters helped..but we made the axes.
>>>
>>> On 11/26/2010 2:42 PM, Bruce Freeman wrote:
>>>> How to melt steel with sunlight:
>>>>
>>>> http://blog.makezine.com/archive/2010/11/2_square_meters_of_sunlight_focused.html
>>>>
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-- 
Bruce
NJ