Viking Age Blacksmith's Bellows

(edited with images from a series of posts to NORSEFOLK)

A layout for a Viking Age blacksmith's bellows that I have seen copied numerous times is the one presented on the Regia Anglorum web site. There are two main problems with the Regia design as depicted. The first is the bellows bags are cut incorrectly as simple triangles. The second is that the overall measurements are not based from the actual historic references - but the proportions are based on modern commercially available lumber. This pictured layout has then been duplicated without those people checking back to the original sources.

I'm not going into great detail here. For a detailed commentary and
working plans for a (speculative) Norse style sand table forge set up -
purchase 'Experimental Iron Smelting from the Viking Age' available on the Wareham Forge web site . (There is a
photo essay on bronze casting on the disk as well.)

There are photos of two versions of the reconstructed Norse double bag
bellows on the DARC web site
(scroll down to the sections on bronze casting and smithing work)

There are two available images of bellows from the Viking Age. One is a
wood cut from the stave church at Hylestad, Setesdal, Norway. This
gives us a side view in proportion (??) to a human figure.
The second is the 'cartoon' from the rock carving at Ramsund, Sodermanland,
Sweden. This gives us top down proportions of length to width and relative size of the inlet hole.

reconstruction for 'World of the Norse'
My estmates from the period illustrations give the rough overall size is about 28
inches long by 20 inches wide (including handles). Each of the main
chambers are about 20 inches long by 10 inches wide. In use, a
comfortable lift to the top plate is about 12 inches (at the handle
end). Average air delivery is about 2.2 litres per stroke.

The shape of the bags is actually a segment of a sphere. So the cutting pattern from flat material is a series of three lens shapes roughly 8 inches at the widest point tapering to maybe 3 inches at either end over a total (for the version described yesterday) of about 48 inches. Double stitching the seams allows for the threading of a wire stiffener into the joint. I have used leather for all of my blacksmith sized reconstructions. To make the 'Ubber Bellows' used for the 2005 iron smelting experiments leather was going to be too expensive. Instead I used a heavy canvas which was painted with tar roofing patch from the hardware (to simulate pitch). This worked extremely well in terms durability and being air tight.

I have made maybe about a half dozen of these at this point. My standard design
uses one solid wood block for the head piece - to which is attached the
two separate bottom plates. This makes it a lot easier to apply the
leathers first! Top plates float of course. The best performance results
from the use of a Y shaped bellows tube (three short tubes joined by a
leather box Y. The advantage of the leather is that it is a flexible joint. This reduces any motion from the bellows action towards the bellows stone itself. I set up the smithing equipment for LAM using this same coupling method.

I have used a heavy modern commercial door hinge under a
leather cover to extend the working life of this joint. The leather is required to seal the top end of the bellows anyway. Kevin has made a
couple of bellows using a heavy leather strip which is re-enforced by a
metal plate on either sides of the hinge joint. This is a more historic
method and has proved quite durable.

Mark Pilgrim, the staff interpreter at LAM has certainly more time at this forge than anyone else in North America. He showed me the trick to the action that Bruce mentioned in his last. You have to start each downward stroke with a small snap of your wrist which comes JUST BEFORE the completed downward stroke on the opposite side. This seems a bit weird till you get the hang of it. The purpose is to start the second exhaust stoke before you start the first intake stroke. This motion prevents any kind of suck back from the fire end.

I have used a heavy modern commercial door hinge under a
leather cover to extend the working life of this joint. Kevin has made a
couple of bellows using a heavy leather strip which is re-enforced by a
metal plate on either sides of the hinge joint. This is a more historic
method and has proved quite durable.

Note on the design - by using the correct wider planks, it is possible
to locate the handles down the centre axis of the bellows plate. It has
proved critical that the operator does not torc / twist the plate as it
is moved up and down. ( I have had metal hinges destroyed by unskilled
operators.)
I have found that a U shaped handle, of a width large enough to place
your handle in the bottom of the U as the most efficient. Both the
historic illustrations show straight bar handles (but also the operator
not actually using that handle).

PS - sorry about the lack of pictures - my terminally slow rural dial up is keeping me from uploading any new images!)