Subject: Re: Solar Powered Forges

From: "daryl (d.a.) bender" <[email-masked]>
Date: Tue, 10 Sep 1996 11:33:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars735.b.179:10.08.96.15.34.20]

You are absolutley right!! I simply took the wattage and divided by 746. 
It is not only misleading it is basically wrong in that we are dealing 
with heat energy and the thermo laws deny 100% conversion to mechanical 
energy (to 20-40%) and the conversion is unnescessary. The stupid thing 
is I knew that however I thought that HP is more easily related to than 
KW.

In message " Solar Powered Forges", [email-masked] writes:
>Well no! I realize you said "equivelant hp" but this is misleading as
>the power is thermal. Just leave it at thermal power as this thread
>is mostley interested in thermal power. Comverting to shaft power is
>complicated and unessassary for the smith.
>
>> >Hoping nobody tells me to put my portable forge where the sun don't
>> >shine 8^)
>> >Daryl

Looks like someone just did! ;^)

>Stupid is Forever, Ignorance can be Fixed

Not sure where that puts me but what can I say other than I should 
*stay* where the sun don't shine 8^)

Cheers
Daryl

---

From: Robert Schryer <[email-masked]>
Date: Tue, 10 Sep 1996 13:31:25 -0500

At 06:12 PM 9/10/96 GMT, you wrote:

>>My design is using 180 square foot of mirrors that reflect the 
>>suns power onto a receiver at the rate of about 10KWatts  
>>including all the losses, if no losses it would be 18KW. 
>> 
>OK - serious consideration here: 
>1. You're talking 80% efficiency here || power out/power in 

  Actually about 56 %  10/18   assuming approx 100 watts /sqft

>    Where are the losses ? - let's figure out how to reduce the losses. 

  Most losses would be in heat and light radiation (as well as convection)
out of the opening where the light enters the furnace.   Thats why solar
furnaces mormally use a larger heating chamber with a small aperature for
the light to enter.  Imagine a ping pong ball surrounded by insulation with
a 1/4" hole in side for the focused solar power to enter.          

>2. If most of the losses occur in the mirrors, it's possible to use gold
>surfaced mirrors with 
>   a silicon monoxide overcoat (to protect the fragile gold plated surface)
>that have a high  
>   degree of reflectivity in the infrared. If you're just talking the
>visible light spectrum, there 
>   are coatings to give you 98% reflectivity. 

        With sunlight it is normally cheaper to just make a bigger collector :)

> 
>>-- 
>                                                  Bill Wyant 
>   Bladesmith / Art Blacksmith / Past President, Ft. Wayne Astronomical
>Society 
>                                    Avalon Ironworks, Ft. Wayne, IN 
>                                        [email-masked]
  Robert Schryer
  [email-masked]

---

From: [email-masked] (Katana ---/-----------)
Date: Wed, 11 Sep 1996 13:09:18 GMT

>a 1/4" hole in side for the focused solar power to enter.           
 
If you made a quasi-black body, non-reflective (absorptive) interior
surface, some kind of black firebrick, you could reduce light emmission and
heat emmission. Convection losses is something we have now in whatever
we're using anyway, I don't see a way of improving that. 
>With sunlight it is normally cheaper to just make a bigger collector :) 
 
True, but if you could use the gold coatings (which are only about 15% more
cost) to  
double the heat output, you could get away with a smaller overall unit,
dispense with 
some of the cost to hold the larger amount of standard silvered mirrors,
and make  
the whole "package" much more attractive to use. The gold is only a few
molecules 
thick, so a pinheads worth covers the surface of the mirror, so the cost
increase is 
almost negligable. Someone's going to build one of these someday, and I'm
thinking 
about it. If it is practical, people will use it. If it's not, it will just
be an interesting 
intellectual exercise. If we can overcome the objections to it, it could
just work. 
Sound like a salesman, don't I ? :+) 
Society

---

From: [email-masked] (Katana ---/-----------)
Date: Wed, 11 Sep 1996 13:17:37 GMT

>I have never tried a chicken but I have thrown in a couple foil wrapped 
>potatos at the end of the day. My gas forge is lined with a castable 
>refractory so it stays hot for quite a while when I shut down. The forge 
>baked potatos fry up quick in the morning. Anyone else experimenting with 
>forge cooking? 
> 
>Bon Appetit! 
> 
>Bob 
> 
Ya - at outdoors events, I have a period looking stainless coffee pot that
I sit right on top of the coal forge, and crank to a medium heat. As long
as it's filled with water, it will not burn. We tell eveyone that we're
having forge welded coffee. A little Irish Cream in the coffee helps too ! 
-- 
               Bill Wyant 
   Bladesmith / Art Blacksmith 
Avalon Ironworks, Ft. Wayne, IN 
    [email-masked]

---

From: "D. M. Dickie" <[email-masked]>
Date: Wed, 11 Sep 1996 06:34:55 -0700 (PDT)

>having forge welded coffee. A little Irish Cream in the coffee helps too ! 
I have been told of an old-time 'smith in the area who lived in a corner of
his shop and did all his cooking on the forge.  In the morning, he'd light
the forge, and put on the coffee pot.  When it was boiling real good, he'd
throw in the coffee and a couple of eggs,  and boil 'em in the coffee, while
toasting a chunk of bread on the end on the end of the poker.  'Bout the
time the toast was done, the eggs were boiled and the coffee was ready. So
much for microwaves!

=============================================================================
D. M. (Mike) Dickie 
FLATLANDER FORGE
Box 85
Pennant, SK
Canada S0N 1X0

[email-masked]

---

From: [email-masked]
Date: Wed, 11 Sep 1996 14:06:32 -0600

Bob
>>
>I've just finished building a gas forge lined with kaowool. However, I
>understand castable refractory is the thing to use in the future. Is your forge
>home-made? What refractory did you use and how did you use it?
>
>Any help is appreciated.
>
>Thanx.
>
>Mark

Hi Mark,

I used a product called Kastolite 2500 ($25.50 per 50lbs.). Its good for
2500 degrees F. Kastolite 3000 ($29.50) is also available. I got it from
the accomodating crew at Smith-Sharp Co. in Minneapolis MN. 1-612-331-1345.

I made my forge with a piece of 14 ga. steel rolled into a tube about 11"
diameter and 12" long. The cavity was formed with a piece of 5" stovepipe
(removed after drying of course). I poured it right around the burner tube.
I wrapped the burner tube (1" pipe) with a few sheets of newspaper first to
provide some clearance for later adjustment.

Its an atmospheric burner (no blower). It will get yellow hot but will not
reach welding heat in its present form (I think a blower would put it in
welding range). I built it for a chisel sharpening job that I do every
week. Its blocked in the back with firebrick and the bottom half of the
front is blocked off too. I cut a piece of angle iron to go across the top
front with a couple slots cut in it for chisels.

It works great and I use it for everything that I can get in it (or thru
it). The Kastolite is holding up well after over a year of use. It takes
about 15-20 minutes to heat up. To figure how much you need it takes 90lbs.
Kastolite (dry after mixing with water) to equal 1 cubic foot. My little
forge took about half a 50lb. bag.

I hope this is reasonably clear. If not ask again.

Bob Schade

---

From: [email-masked] (Michael G. Cooper)
Date: Wed, 11 Sep 1996 15:07:15 -0700 (MST)

I built my first gas forge with castable refractory and I was dissapointed
in its performance.  The refractory I used was dense and robbed heat from
the forge until it heated up, lengthening warmup time before I could use it.
I later lined it with ceramic wool (Kaowool) and was much more satisfied.
Since the bottom wore out quickly, I bought a fire brick of the high temp,
low density variety for the bottom.  You can extend the life of the
insulation by coating it with soduim silicate, available at the same pottery
supply where you got your insulation.
Mike C.

---

From: [email-masked]
Date: Thu, 12 Sep 1996 10:08:12 -0600

>I later lined it with ceramic wool (Kaowool) and was much more satisfied.

The longer warmup time works to your advantage when doing a production job
(chisel sharpening). The slower to heat castable is also slower to cool. I
think they call this thermal mass. The burner can keep up with the heat
loss (chisels) if the forge is cooling slower.

Bob

---

From: "daryl (d.a.) bender" <[email-masked]>
Date: Wed, 11 Sep 1996 16:03:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars520.b.372:11.08.96.20.28.21]

In message " Solar Powered Forges", [email-masked] writes:

>the forge, and put on the coffee pot.  When it was boiling real good,
>he'd throw in the coffee and a couple of eggs,  and boil 'em in the
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>coffee, while toasting a chunk of bread on the end on the end of the 
^^^^^^^^

Yup, I think that would wake me up. Not a nice way to wake up but it 
sure would wake you up none the less

Yech
Daryl - not a child of the "well it all gets mixed up anyway" school

---

From: Russell McCrackin <[email-masked]>
Date: Thu, 12 Sep 1996 12:41:35 -0700 (PDT)

To all:  This reply contains a lot of science type stuff that you
may not be interested in, so if science bores you, trash it without
reading it.  And it is very long.  Don't say I didn't warn you.
But Duane C. Johnson wrote a reply to one of my replies,
and this is my reply to him.

Duane wrote:
>Hi all;
>This is my first post to this list as I am not a smith yet.
>I have been accumulating stuff to get started as I have been 
>fasinated by smithing since the fiftys when my father would
>get things fixed at a blacksmith shop in Mora, MN.
>
>I have been lurking for a while. BUT I have to respond now.
>I can take a joke as well as anybody. I give a lot of them 
>also. I am an incurable punster. The solar thing has been
>fun. BUT!
>
>I am a designer of high powered solar heliostats. My prototype
>is not designed for high temperature but it can produse high 
>temperatures and high poweres when needed.
>
>This is not an insignificant amount of power. It is serious
>power.
>
>Russell McCrackin wrote:
>> 
>> At 11:42 AM 9/9/96 -0400, you wrote:
>> >Only 1 square meter?! That's a pretty good output!! There are electric
  
Big Snip

Rusty writes:
Here you (Duane) included a LOT of stuff that I (Rusty) did not write.  
If you note the use of the > and the >> and the >> >> you can see that 
I was not the author of much that you included under that heading.  
Please be careful about who you give credit to for items of  content.  
Better to leave out the author's name if you aren't sure who did it.
In my reply, following, I will identify those parts that I did write.
>> >>
>> >>The problem is to get enough power. One square meter will get you about
>> >>one kilowatt at best (that will just about run a big hairdryer).
>> >>Heating tiny things might work though.
>
>Correct. Melting aluminium and forging steel takes real power.
>The sun has plentu of power. You just need to gather enough of it.
>
>> >>
>> >>Ralph
>> >>[email-masked]
>> >>
>> >
>> >Ralph has it right.  The problem is getting enough power.  And the
>> definition of power is energy per unit of time.  So use the solar energy
>> forges you already have.  (I'll explain that statement later.)
>
I (Rusty) did write the above paragraph to Ralph.

Duane wrote:
>You have your units backwords. Energy is power per unit of time.
>We must be careful in the usage of scientific units when calculations
>are made. I fully understand that many like to use oldtime homey
>terms when describing there historic craft. Even the oldtime smith,
>though he may not have had the language correct, knew instinctivly
>the difference between "power" and "energy". Power is how fast
>you can heat somthing up, Energy is how much coal was needed to do it.

Rusty writes:
Here, you really blew it.  The definition of power (energy per unit of time)
is what I learned and used through High School and 9 years of undergraduate
and graduate college courses in engineering and Physics, and used in 6 years
of engineering, 27 years of teaching Physics Majors during my years as a 
Prof. of Physics, and as a blacksmith in "retirement."  If you change
your phrase slightly to "energy is power multiplied by time" you are correct.

     P = E/t   (energy per unit of time)   and     E = P x t

Class time:  the definition of the scientific unit called the "watt"
     One Watt is one Joule of energy per second.
Yes, this is the "oldtime homey term" for the watt, but it is still being
used in all scientific work all over the world.

Then you say that power is how fast you can heat something up.
In other words, how much heat energy you can put into something per unit of
time.
Correct.  That is what I said, i.e., power is energy per unit of time.

The "Energy is how much coal is needed to do it" depends upon how much energy is
stored in a unit of coal. (how many BTUs per pound, as an example.)

>> Yes, the full sun when overhead on a clear (I do mean clear) day
>> will give you energy at about the one KW or 1.5 HP rate.  But when
>> the sun's rays slant the path through the atmosphere is longer,
>> water vapor, dust, smog, smoke, various "air polutants,"  all reduce
>> the amount arriving.
I (Rusty) wrote the above paragraph.

Duane wrote:
>This is a misnomer. The power of the sun dosn't differ very much
>due to it's position in the sky. Ok, of course, it is less near the
>horison but not a lot less. (I am being vague here). Any solar forge
>would of nessesity have to track the sun and not lie flat on the 
>ground. 

Rusty writes:
The power of the sun itself is fairly constant, yes, but not the amount
you can receive.  Increasing the amount of material between the sun and
a "solar forge" will reduce the amount available to the forge.  In other
words, the atmosphere and its contents act as a variable desity ceiling
that "shade" us here on earth.  The "holes in the ozone layer" allow us
to receive more ultraviilet light, etc.  When the sun approaches the
horizen, the energy has to travel through a longer path of atmosphere, 
and less energy per area arrives at the earh's surface.  And each time I
talk about the energy per unit area, the areas is assumed to be at right
angles to the incoming energy path.
>
>> The amount arriving isn't what you are going to get to use.  A perfect
>> "black body" would collect it all, but most materials will reflect more
>> than 80% of what hits them.  That's the reflected light that you see
>> them by.
I (Rusty) wrote the above paragraph.

Duane wrote:
>I think you are wrong abot this. The sun is a black body radiator 
>at 10000 degrees kelvin. Your metal is not this hot. For the object
>to reradiate 80% it would have to be at about 8000 degrees kelvin.
>( Ok not exactly but not far off). Your object will accept the
>majority of the power shining on it.

Rusty writes:
A black body will radiate as long as there is any heat energy in it to
be radiated, regardless of its temperature.  The higher the temperature,
the greater the amount of heat radiated per unit of surface area.  The
equation for radiation by a black body includes the absolute temperature
raised to the fourth power.

The equation reads :
  The amount of energy radiated per unit area per unit time equals a constant
multiplied by a factor, whose value is between zero and one and depends upon
the surface texture and color, mutiplied by the forth power of the absolute
(Kelvin) temperature.

    To convert Kelvin to Fahrenheit, subtract 273 from Kelvin, which gives
the Celsius temperature.  Then multiply by 9, then divide by 5, then add 32.

    To convert Fahrenheit to Kelvin, subtract 32, the multiply by 5, then
divide by 9, which gives Celsius, then add 273.

>> If you can use mirrors to reflect additional energy to the collector, the
>> collector will get hot. (Solar One, the solar experiment by an oil company
>> and the Southern California Edison Co. is an example.  But their absorber
>> gets visibly hot, which means that a lot  of the energy to it is radiated
>> away, and does not go to the electrical generating system.)
I (Rusty) wrote the above paragraph.

Duane wrote:
>I agree with this. The fact that radiation occures dosn't stop the 
>system from working though. This is one of the engineering factors to 
>take into account when generating power. 

Rusty writes:
The energy receiver reflects as well as radiates.  The reflection reduces
the amount of useful energy received.  Then the radiation reduces it more.
When there was serious dicussion of using solar energy collected in the
Mojave Desert to generate electrical energy to be delivered to the L.A.
basin, the "Grand Scheme" pictured the desert literally covered with
mirror groupings, or direct solar cells if they became efficient enough.
   What they didn't consider is interesting also.  Can you imagine how
the Environmentallists would react to covering all that "empty land" and 
destroying the plants and animals that depend on the sun energy for 
their existance?  
   Another consideration:  Taking all that sun energy from the desert and
shipping it out as electrical energy would mean less energy to heat the
desert.  If the desert is not heated as much, there would be less heating
of the air above by re-radiation.  Less heating of the air would result
in less expansion of the air during the day, which would mean that there
would be less thermal lifting of the air, and there would be less air
motion along the ground into the air.  And a lot of that air now comes
from the L.A. basin, and clears some of the smog out of the basin in the
afternoon.  So generating electricity in the Mojave desert would mean more
smog in L.A.  Maybe they could use the extra electricity to run giant fans 
to blow the smog over the mountains and into the desert?  Yes, that was
actually proposed!
> 
>> You can cook a chicken with a solar stove, but I don't think you will
>> be using a direct solar energy forge with mankind's present knowledge.
I (Rusty) wrote the above paragraph.

Duane wrote:
>Of course you wouldn't cook a chicken in a forge either. We are talking
>about apples an oranges here. 

Rusty writes:
Yes, I would cook a chicken in a forge.  In fact, I have already done so.
Chicken and lots of other stuff.  I don't put it right inside the fire,
but I don't do that when I use a stove in the house, either.
My reference to cooking a chicken in a solar forge comes from a "few"
years ago when magazines carried ads for solar cookers.  Umbrella shaped
reflectors about 3 or 4 feet across that were used to cook things.  Some
of them were taken to South America and given to the natives so they
could cook their food without burning wood, which the natives thought was
an absolutely ridiculous idea.  They didn't have to carry wood when they
moved.
> 
>> So let's all just use our present solar energy forges.  Yes, you
>> read me right.  Any fossil fuel you burn, natural gas, coal, alcohol,
>> charcoal, old corn shucks, old emails from Rusty, it's all just stored
>> up sun energy, stored up a little at a time, over a  very long time, and
>> used in a very short time.  A lot of energy used in a short time is a lot
>> of power.
I (Rusty) wrote the above paragraph.

Duane wrote:
>Come on guys think positivly about this. Solar forges can have some
>positive aspects. How would you like to have a forge that:
>
>1. Had no reactive gasses?
>2. Could heat things not just to melting temp but to vapor temp?
>3. Produced no scale?
>4. Produced steal that was fully shiny, not black, when done?
>5. Could heat things like titanium or magnesium without combustion?

Rusty writes:
Comments about the 5 items above.
1. Had no reactive gasses?  If you heat air composed of mostly Nitrogen
and Oxygen to about about 650 F the oxygen and nitrogen start to combine
to produce NO2 and NO3 (the 2 and 3 should be subscripts) which are what
are generally called NOX, as in air polution.  Any fire, inside a car
engine, a fireplace, a forge, or campfire does this.  
2. Could heat things not just to melting temp but to vapor temp?
Anything hotter than welding temperature I don't want!  If you are going
to heat to melting temperature of steel, you better have a way of keeping
the air away from the steel.
3. Produce no scale.  If steel is heated in the presence of free oxygen,
it will get scale.  If it is in the presence of free oxygen at any 
temperature, it will get scale.  Some times it is black, and sometimes
it is a rusty color.  How is a solar forge going to prevent that?
4. Produced steal that was fully shiny, not black, when done?  See 3 above.
5. 5. Could heat things like titanium or magnesium without combustion?
So titanium and magnesium don't oxidize the at the same rate that steel does,
but I don't see how using a solar forge will make and difference.  Keeping
oxygen away will, but sunlight won't.

>> Rusty
>> 
>> Get it hot and hit it hard.
>> 
>> Never use force, get a bigger hammer.
I (Rusty) wrote the above signature.

Duane wrote:
>I apologize if I have offended you but I think we need to 
>try to work with new ideas as well as with the old. The smith
>of old was working on the leading edge of technology in his time.
>We need to work at the leading edge of technology of our time.

Rusty writes:
No, Duane, I am not offended in any way, and I also hope that you
are not offened either.  I agree on using new ideas as well as old,
and am currently using tools made from alloys that were undreamed 
of not too long ago.  Time allows us to learn new things that 
change ideas and understandings.  

Duane wrote:
>This solar thread has inspired me to look into a solar powered
>forge. Anyone want to use it if it workes next summer?
>
>Did you hear the one about the solar guy from Barstow.....?
>
>---
> 
>CUL8ER
>
>Stupid is Forever
>Ignorance can be Fixed
>
>Duane C. Johnson
>Ziggy
>WA0VBE
>Red Rock Energy
>1825 Florence St.
>White Bear Lake, MN, USA 55110-3364
>(612)635-5065 w
>(612)426-4766 h
>[email-masked]
>[email-masked]
>http://www.geocities.com/SiliconValley/3027/
>
Rusty writes:
If you got this far, and you are not Duane, then you have an
amazing ability to take punishment!  I wish solar forges, 
induction furnaces, etc., were available and inexpensive, but
I probably won't live long enough to see them happen.  The
truth (as I see it) is, we aren't going to find a way to do
it cheaper, quicker, and easier, and if we did, would we
want to do it that way.  If so, why did I pay so much for
a leg vise when I already had a good vise on the corner of my
bench?  Why do I have 3 hand cranked blowers when I usually
use an electric blower when I run my forge?  Why do I make all
my own tools when ever possible, when they are often available
in the 106 yr old hardware store right here in town?

And finally (atlast), Duane, don't give up thinking, dreaming,
and trying.  If the solar forge works,fine.  If it doesn't,
the experiment is not a failure.  I used to tell my students, 
"No experiment is ever a failure.  It just says you can't do
it the way you tried."

Rusty

Get it hot and hit it hard.

Never use force.  Get a bigger hammer.

 [email-masked]