The Dragonfly






 Last Update-03/13/2010 01:41 AM           

  I have decided its about time to take the next step and add a little foundry to my shop.  I'm not sure where I'm going put the furnace with all the extra stuff piling up in the shop,, but I'm sure I'll figure it out when I need too.

I have decided to build the furnace  (pictured to the left) outlined in David Gingery's book: "Building a Gas Fired Crucible Furnace"  I like the way the furnace is designed.  It gives the operator the ability to raise and swivel the lid out of the way when needed and the ability to raise the body and lid together with a cantilevered, lever action handle that holds the whole affair up while you remove the crucible for pouring. 

At left , you can see a cutaway view of the furnace in its closed position.  On the right, the furnace is in its "crucible insert/remove position" with the body and lid raised with the lever.  The lifting lever cantilevers back and holds the weight while you do your work.



You start off by building the inner form that creates the inside of the main body.  Its simply 26 gauge galvanized sheet wrapped around some plywood rings.  (I am not going to detail sizes as I think that would be taking away from Mr. Gingery's  ability to sell books.  His book is inexpensive and is worth every penny.) The inside form is made in such away that it can be broken down and removed after the refractory has set-up.


AT left is just another picture of the inside form.  On the right is a piece of 24 gauge steel sheet Ill use to create the body part forms.



On the left are the cut to size form pieces for the lid, body and base. 

At right I have the pieces trimmed, drilled and ready for rolling into round forms.  As you can see, this is a fairly easy project thus for.


I have finished forming the blanks into round forms that will be filled with refractory to create the base, body and lid.  I stacked them up as they would set on the stand to give an idea of how they set together. (which I'm sure by now you have figured out anyway)



The air and fuel come into the base thru this burner inlet port that is cast into the base refractory.  The pattern on the left was created in AutoCad (2006 for those interested in what I have),printed and used as a pattern to layout the round fitting.



The burner inlet port as it sits against the inside form.