This is meant to be an addendum to Campsite Crafting 05: The Bloomery
I’m going to need some help with this. I found an out of print book called “The Navajo and Pueblo Silversmiths” which describes the ‘primitive’ bellows.
Here’s the passage that may be relevant:
“…. The three uprights and the ribs are of oak, from a tree felled on the Zuni mountains twenty miles east of the pueblo. Thongs draw in the hide between the ribs, forming three compartments on each side of the center upright. On this bellows, the air spout, made of rawhide, is mounted on the center upright, and there is one intake on each end of the leather bag. An Iron Bar passes through holes drilled in the upper end of the wooden supports and keeps the air bags in line. The top of one of these uprights serves as a handle by which the bellows is drawn in and out. The other one of the two uprights is fastened in a stationary position.”
“… in the Navajo bellows, if one may judge from a photograph of one. In the Navajo bellows, the intake is at the opposite end from the outlet, and on a line with it, while in Keneshde’s bellows, the intakes are in a transverse position. There is an advantage in Keneshde’s construction in that he has made a double bellows, which may be worked by pulling only one handle, while the other hand is left free for manipulating the crucible… The navajo smith built a double bellows by placing the two air chambers side by side, instead of one adjoining the other in a single construction. By pulling and pushing the two handles of the bellows alternately, a steady draft issued from a bifurcated spout.” – The Navajo And Pueblo Silversmiths; John Adair
Actually making bellows is kind of a complicated task, but if we want to melt metal, we need them like the red warrior needs food, badly.
Unfortunately, without advanced tools, or precise measuring equipment, we have to work with what we can fabricate in the wild at our current level of technology.
We have a knife, probably a few knives at this point, made of stone, flint, and bone. We have clay. We have hide. We have glue, and we have bone.
The basic function of a single bellows is thus; a wooden or metal frame that is encased in or encasing an ‘air bag’ with an intake and a spout. When the bellows are pulled open, by a pair of handles joined at a fulcrum, the intake ‘valve’ or flap opens filling the bag with air, like your lungs when you inhale. Then during the reverse action, as the bag is compressed, the intake flap closes and forces the air out through the spout, so it can be directed into the Tuyere, into the furnace, allowing the coals to burn hotter and hopefully reach the melting point of our metal.
Making this device is simpler in theory than in execution.
The theory is that we’d make a pair of A shaped frames out of a soft wood, an air bladder out of rawhide, and a nozzle out of some fire-clay. Lash the construct together with cordage, and seal the bladder with hide glue.
The issues that need to be resolved:
Making our intake flap requires some delicate leatherworking, as it must seal tight when the bag is compressed, so that the air is forced out of the spout.
One suggestion was why make a separate intake valve – while it may work to make a single port in the air bladder and use it for both inhalation and exhalation, each time the bellows is stroked it would have to be removed from the tuyere and reinserted, a viciously inefficient practice. Once we can start making simple metal tools, we can update our bellows with a more effective Double Bellows system, and eventually build machine bellows, but until then, we’ll try to come up with other ways to extract that iron ore.
I’m also looking for schematics for a Roman Bellows, if anyone comes across them drop me a line at SurviveWhatever@gmail.com.
Using our primitive tools, we’ll be destroying a lot of materials in the trial & error attempts to actually construct the final device.
If anyone would like to draw up some schematics, I’d appreciate it, I have no hand for art.
As I experiment with this process, I’ll update this entry.
Edit: Thanks Sam
I’m looking into bag bellows, and hopefully I’ll be able to find a simple tutorial I can hijack and incorporate.
If we can make a bag bellows work with buckskin that might be a primitive enough solution to work into the technology ladder.