[TheForge] propane burner poll

[Bruce Freeman]

I just looked up Zoeller's forge:

http://zoellerforge.com/simplegasforge.html

This is virtually identical to the forges NJBA has built.

The tin can shell works, but we prefer to "roll our own" from sheet
metal -- preferably SS.  Slip roll needed.  Those 5-gal tin cans are
getting scarce these days, and the plastic ones hardly last one
firing!  I've heard of guys using 1' dia. tubing with 1/4" walls, but
you really don't need a bulletproof forge, and the weight of such a
thing is excessive.  Rolled into a tube, 14 ga is probably overkill.
(I don't recall what we last used.)

We prefer to leave both the front and back open and to provide a door
insulated with 2" of mineral wool to seal the back.  The same could be
done on the front, but insulating firebricks are easier.  For long
work, you remove the back door and pile bricks front AND back.

"Durablanket" is a brand name.  Other brands of mineral wool will do.
For a 1' deep forge (good for anything but swords) you need mineral
wool that is 1' wide by 2" thick.  You can do it with 2' wide by 1"
thick, but you'll do more cutting.  (Cutting is easily done with a
knife pressed through the blanket against a stick of wood.  Wear a
face mask and gloves, and change out of your clothes ASAP.)  As he
says, you want the 8# mineral wool rated to 2300*F.   You'll find this
at boiler repair shops (along with castable refractory).  Some shops
may have to  order it for you.

The firebrick  bottom is essential.  I prefer cutting holes in the
mineral wool below this and to place some rigid firebrick pieces in
these to support the brick.  Even firebrick is not resistant to
welding flux.  I've found a thin piece of SS sheet metal curved to fit
the bottom of the forge helps protect the refractories.

Our burner is different from Zoeller's, but functionally similar.
(See "Bienstock Burner" on http://ronreil.abana.org/design2.shtml )
Ron's criticism of its length strikes me as irrelevant, and it was
actually easy to build in quantity, once we jigged up for it.
Remember, we built about a dozen of these at a time.  Requires arc
welding.  I have no data on comparative performance of these burners.
My impression is that virtually any design of an aspirated burner will
work if the general design is followed.  (If  you want to get
sophisticated, get the venturi from a gas furnace for a more gradual
transition.)

On thing -- for use in a gas forge lined with mineral wool, there is
no need for the burner to have a flame retainer (that outer tube
around the burner nozzle).  The mineral wool glows incandescent
immediately the forge is lit, and keeps the flame burning.  Without a
flame retainer, the burner will not work outside the forge, however.

On Sat, Oct 15, 2011 at 7:17 AM,  <mlforge at cebridge.net> wrote:
> Larry Zoellers is the easiest to build, the other 2 are porter burners as in his book, more adjustment but not a great improvement. Look at the burner Nathan Roberts is selling, thing they are an inprovement. Will get contact infro if needed Ralph

-- 
Bruce
NJBA