Forge Fire and Bellows: Andrew, The only difference between an open fire and a forge is a forced air supply from a bellows or blower. The open fire works if there is a slight pit with the forced air coming in from the bottom.

You start fairly large and burn down to coals. At that point the forced air will produce a white hot fire. Once you get going you feed a little more wood in at a time. However, this makes a very smokey fire that if hard on the eyes and lungs. If you coal the wood first then the fire is cleaner, hotter and much more efficient. Many places where you see indoor fire pits with no chimney and a roof vent and burned charcoal, not raw wood.

There are many primitive bellows types.

The most primitive type is blanket or hide over a pit, the esges stakes down and sealed with dirt. The hide is lifted by the center with a corner held open to let in fresh air, then the corner hled down as the center as the hide is pressed down slowly. This requires one or more helpers that can withstand kneeling or squating on the ground for hours (as is the case with many primitive bellows).

Slightly more developed is the wineskin. This is the stomach of an animal that has been prepared to carry water or wine. Two are used to pump air into the tuyeer (the pipe or passageway leading into the fire). A hole in the end that is opened and closed by hand acts as an intake valve for fresh air.

Paired bellows were the next step in the evolution. These were boards seperated and hinged with leather and had an internal flap valve (check valve) for the intake. A pair was used to create a steady flow of air. They could be operated individualy with short handles or as a pair with a rocker handle that leift one up while it pressed the other down. Properly built the outlet nozzels were close together and blew air into a seperated tuyeer creating a pneumatic check valve preventing hot air from sucking into the filling bellows. Most are not properly built in this regard.

The Great Double Bellows was the ?apodeme of lether bellows development. These are two bellows built one over the other with a common stationary board. There are wood or leather check valves in the bottom board and the center board. The bottom chamber pumps air into the top chamber and the check valves between them positively prevents the air from going back. This was a true positive displacement pump and is the style of bellows used for hundreds of years.

The Oriental Alternative is the box bellows. It is a long wooden box with a board that acts as a piston to move the air. The piston is moved by a long slender round or square wood rod that passes through a snug hole in one end of the box. Each end of the box has intake valves. There are two designs for exhust valves. One style uses two valves and a manifold on the side of the bellows. The other has air passages in the bottom and a single valve that closes the outlet of each chamber alternately. The second type is a very clean design but takes a little more knowledge and skill to make.

The advantage to the oriental box bellows is that it uses no leather and is cheaper to construct as well as more durable. While it provides an almost ?continuous blast of air there is a brief moment of switching similar to the paired bellows. 


Cultural Advisory-- PBS has a thing on tonight called Guns, Germs and Steel, a Nat'l Geo 3-parter examining howcum some civilizations do it and some don't. On at 9 p.m. in the greater Albuquerque viewing area. (Followed at 10 by an historical thing about the Zulus clobbering the Brits, this time without the help of Michael Caine and Jack Hawkins.)
Miles Undercut - Monday, 07/11/05 20:55:46 EDT


Zulu Blacksmiths making a spear point 1879

OK, THIS is a primitive forge. The interesting thing about this scene is that it would be filmed as a 10 second scene in King Solomon's Mine staring Paul Robeson and Sir Cedric Hardwicke filmed in 1937 using extras that were in fact real Zulu blacksmiths.

A couple years ago a fellow from India sent us a photo of a poor local smith using a pit forge with an electric blower. The 19th Century meets the stone age. . . He said the clay was bonded with the waste from the "sacred cow".


The image below was drawn of Zulu Blacksmiths in 1879. The book King Solomon's Mines, first published in 1885. Later in the classic British movie "King Soloman's Mine", staring Paul Robeson and Sir Cedric Hardwicke filmed in 1937 with the exact scene below. For all of 10 seconds a bit of ancient technology is recorded. The guys in the film knew what they were doing unlike the common actor we often see who has never held a hammer. . . The only difference from this 1879 engraving is that the guys in the film were using short wooden tongs.