Re: Forging Info Needed

To address a few comments from the various posters -

Steve-
    Melting cast iron with propane would be difficult - you'd get further
using coke or even charcoal I believe. I think that it is possible, but a
serious attempt would probably require an O2 line somewhere.

John-
    I definately agree - whatever suits the situation. I've got some real
old torches - almost antiques - I love em' for brazing because they are
hotter than a Bernzomatic, but not as hot as the OA.

Andy & Jerry -
    I definately agree, burning oils, plastics, old tires, etc, it all
produces a disgusting black cloud of smoke which contains some of the most
toxic substances known to man. <<< This is true. However, if you burn any of
these materials correctly they will go through complete combustion to
produce harmless gasses just like anything else. The trick is maintaining
extremely high furnace temperatures and balancing O2 ratio correctly. Many
environmentalists >recommend burning< used motor oil for home heating
because that will keep it out of groundwater. There should be no heavy
metals in used oil - just some iron and mabe some aluminum - very little.
    There is a guy who made a furnace unit for burning old tires. This thing
is patented, is it recouperative, some of the heat from combustion is
channelled back to melt and vaporized tire feedstock into vapor, this thing
burns like the gates of hell and produces no smoke. That's right, he burns
old tires and there is no smoke. This produces a tremendous amount of heat.
    Of course, if you are making black smoke then you are definately
polluting.

Steve again -
    Check out various refractory materials. You can spend a fortune, or you
can do things without spending a fortune.
    Sand - SiO2, is an incredible refractory material. It is also free.
    Fiberglass is dirt cheap, but cant take too much heat.
    Ash, thoroughly washed, makes a great refractory.
    Perlite is great stuff.
    Vermiculite is pretty good stuff.
    One of the best insulators is motionless air. Cenospheres can emulate
still air.

    Never use portland or plaster as a binder. It will not work. I might
explode, and it will definately melt at low temperatures.
    For a decent binder, use sodium silicate solution from McMaster Carr
(cheap).
    Colloidal silica is also a good binder if you can get it. You can make
your own by acidification of sodium silicate solution but it must be
stabilised by titrating to very slightly basic otherwise it has no shelf
life. It is also very easy to make your own sodium silicate if you really
wanted to.
    Some clays will also work, the best is Kaolin. Some clays melt at high
temps, but some can take the heat.
    There is a material - I think it's European. Cant remember the name, but
they use it for electrical insulators etc. This stuff is a formulation of
silica, mica, and glass. The glass melts and acts like hot glue. It is
considered a ceramic material, might be OK for a furnace. Not sure.
    If you REALLY want the hottest furnace in town, try making yoru own
fused silica tiles. All you need is a good source of clean sand. Now melt it
and let it fuse. You will need an extremely hot furnace for this. The
resulting fused silica is an EXCELLENT refractory, and it has an incredible
resistance to thermal shock. You will probably need O2 to get things hot
enough, but it is probably worth the effort.
    And on, and on, and on...............