Thursday, April 18, 2024
Wednesday, April 17, 2024
Mounting Fire Base Activities
Mounting Fire Based Activities
Considering Ground Surface Impact
Introduction
A physical demonstration of many crafts activities requires the use of high temperatures as a transformational method. Those involved with living history presentations have a secondary problem, as modern generated heat sources (torches) or containments (metal ‘fire bowls’) are obviously not historic methods.
Land owners may have established a ‘no ground fires’ rule. There are several underlaying (logical?) reasons :
- Not wanting surface lawns to be damaged.
- Not wanting to have pits dug into the ground
- Concern about transportation of fire wood, or gleaning activities
- Concern about potential dangerous spread of a poorly managed fire
- Concern about the liability aspects of burn injuries
Generally these concerns are expressed by three commonly stated rules :
- Only fires on raised metal fire bowls
- Only fires in specific pre-determined and equipped locations.
- No open fires of any kind
Event organizers need to be fully informed of the technical requirements related to individual craft methods. The physical size or working dynamic of a specific activity may itself impose limitations on how to properly and safely layout a fire based heat source. This is especially the case for historic demonstrations which will require the use of wood or charcoal fuel. A good example would be glass bead making, where modern practice is to use bottled gas torches the historic method is using a small enclosed clay furnace, charcoal fueled.
Often the response when contacting event Organizers, who may be constrained by simple rules dictated by land owners, is something like ‘You can work at the edge of the single shared camp fire.’ This is not a workable solution, as craft working requires considerable control of fire sources, if not specialized builds entirely. The desire for a companionable ‘fire circle’, or need for group cooking are just not compatible for the technical requirements for metals casting as one clear example.
There are a number of possible solutions that can be utilized by conscientious and experienced crafts workers that should fulfill at least the requirement for general safety and prevention of ground surface damage. Artisans need to explain these solutions in clear detail, Organizers need to understand physical requirements.
Contained Fires
Many historical craft techniques utilize fires inside specifically fire proof containers. Examples would be small glass bead making and metal casting furnaces. Larger and longer duration fires for ore smelting, pottery firing, even bake ovens, again all require durable containments. In all cases the purpose of these builds is specifically to hold the fire inside, concentrate and control these fires for correct function over time. Because of this technical requirement for fine control of heat, constant management of a very specific sized fire is necessary. In all these cases, the fires are normally contained inside clay or brick walled structures, and can not be in any way considered ‘open’.
Even the most extreme of all the potential fire based historic methods, bloomery iron smelting, requires a structure intentionally designed to withstand internal temperatures in excess of 1350 °C, over a day long operation.
Experiment /
Demonstration of ‘Celtic’ bronze casting by Rey Cogswell during
their Master’s studies at University College Dublin in 2018. Clay
walled melting furnace to rear, stone walled crucible warming fire in
front, both mounted above ground surface.
Surface Protection
Often land owner rules will state ‘raised fire, just because this is the easiest description. It is expected that Organizers will be logical when considering the following long proven options for safety and limiting surface damage. The question needs to be considered : ‘How high does ‘raised’ actually mean?’
Iron Smelting Furnace built on concrete pavers preserving a grass lawn. At Western Michigan University, International Congress in Medieval Studies, 2013.
Smaller furnaces can be built on special purpose refractory plates, such as pottery kiln shelves, or even on slabs of thin stone.
Demonstration
of the high temperature Aristotle iron re-melting
furnace. This furnace is about 20 cm at the base, and safely sits on
a refractory plate. At a Society for Creative Anachronism event.
If absolutely
conserving lawn grass is a consideration, lay down a standard wooden
shipping pallet, then place the same concrete slabs on top. This
method was first devised in 2005, when a full iron smelting
demonstration was mounted on archaeologically sensitive ground
(Canadian National Blacksmith’s Conference at Annapolis Royal NS).
It has been used repeatedly to also conserve concrete flooring and
decorative lawns, and proven to have virtually no impact after being
removed. Positioning several lengths of 4 x 4 lumber will also leave a protective air space below the concrete plates.
For smaller furnaces, the same effect can be achieved by laying down a couple of cut to fit pieces of standard 2 x 4 lumber. In either case, and potential heat transmitted downwards through the fire proof plate is vented by the air space created underneath
Faced with the problem of not damaging archaeological ground in Britain, but still wanting to create a historic looking solution, the long standing living history group Regia Angolorum (back about 1990?) developed a protective design suggested by a panel from the Bayeux Tapestry.
In it’s simplest form this is a set of clay bricks, placed loosely on the ground, contained in a wooden framed box. These can be covered with a thin layer of sand, which both hides the more modern bricks and also will fill any gaps between bricks. The basic design can be improved by laying a piece of light sheet metal down first. More elaborate equipment is also constructed along the same principle, with use of short legs to lift the entire surface clear of the ground. This form is more commonly seen in European re-enacting, where the problem of not marring archaeologically significant ground is always present.
No details of who / where. The fire surface appears to be a 10 cm deep bed of sand seen to the left end. – uncredited internet source
These fire boxes, on the ground or raised, were introduced as a response to a specific problem inside a specific region, they are also being applied for cooking purposes only. A slightly smaller version may be suitable for supporting smaller furnaces (metal / glass bead work). These activities require quite specific heights for safe and efficient working. Again, physical transport needs to be considered, with table frames, crates of bricks and pails of sand.
It is worth remembering that the most common solution suggested, a completely modern stamped steel dish, is not suitable physically for containing a craft working furnace or kiln. What is required for any of this equipment is a flat supporting surface, not a depressed bowl.
Value of Experience
Organizers need remain aware of the value of the accumulated experience of individual Artisans. This may be considerable, and certainly any long working artisan will be fully aware of the operating dynamics of their heat sources and safety measures involved. Rather than applying a simple blanket rule, individual cases need full consideration. Organizers should never forget the considerable effort undertaken by Artisans, and the overall value any physical demonstration brings to their event.
Wednesday, April 03, 2024
the 'French Nail' : Field Expedience
I was recently contacted by a long ago army buddy, who was looking to have some replicas made of an early World War One object.
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| Image from the Imperial War Museum |
'French Nail' fighting knife ['Clous Français']
The reference he provided was from the Imperial War Museum : https://www.iwm.org.uk/collections/item/object/30003377
These were not 'regular issue' weapons, but were made at the front by blacksmiths working primarily as farriers, who's primary role was shoeing all the horses and mules used for the bulk of transport in that conflict.
The basic raw material was supplied by converting 'screw pickets', steel posts used for holding strands of barbed wire in entanglements.
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| Photograph by Lt. J.W. Brooke : 1917-10-23 (IMW) |
The IWM description provides the following dimensions (of the sample pictured above) :
Depth 11 mm
Height 318 mm
Width 54 mm
Weight 0.314 kg
As is my normal practice, I took the reference image and converted it to life size, and printed off a copy.
My first surprise is the diameter of the round bar used. I would have expected French metric sizes at 10 mm / 3/8 inch. That 11mm is just a strange size, converting to imperial to 7/16. These knives were also made and used by both British and American troops, where I would expect 1/2 (12.5 mm) stock. Given the few clear reference images I could find of British (hence also Canadian) troops with screw pickets, I decided to use 1/2 round mild steel stock.
In use, the hand would grip inside the ring, around the blade side. The blade would point upwards from the thumb. This allows for a 'low line' stab to the gut. The heavy loop of bar thus runs over the fingers, creating a 'knuckle duster' effect for punches. The knife is primarily a stabbing tool, so the long point is more important than the cutting edges. Simple, brutal, efficient.
From the life size image, I pulled the following additional measurements :
Blade : 20 mm / 3/4 inch wide x 15 cm / 6 inches long
Handle Interior : 80 mm / 3 1/8 long x 30 mm / 1 1/8 wide
The handle interior space was a bit puzzling, being a bit on the small size. I have fairly small hands and would have found the historic sample a tight fit.
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| The two replicas, upper as diamond / lower as triangle (on 1/4 " grid) |
As a primary thrusting weapon, the blade cross section could have been either diamond or triangle - either would produce two cutting edges. The most likely would have been a more standard diamond, but the triangle results in a thicker, and thus more rigid, central spine. None of the images or descriptions I could easily find via the internet specified which. As a forging test, I decide to make one of each cross section. The one closest to the reference sample (smaller hand grip) as diamond. The second replica was made with an intentionally larger interior grip size to fit a more modern physical build, and I used a triangle cross section. I was a bit surprised to find the forging steps required for either turned out to be pretty much the same. The diamond needed forging on four sides, but the triangle I found needed more control with the hammer blows (although admittedly not a shape I make that often).
I also made some trials working 1/2 round into a triangle bottom die. The die I had on hand was more of an equilateral triangle, so not ideal for the wider final shape required. With the proper shaped die made up, the time to forge the triangle cross section would be greatly reduced, and the forging would produce both a significant central spine as well as thinner cutting edges. This most certainly would speed the work if a smith had a large number of requests for this knife. (Worth noting that the sample does not show the more exaggerated cross section suggested by the test pieces I made.)
Monday, March 25, 2024
'History in the Wind' - past work as prototypes
The last posting showed my design rough for 'History in the Wind', but was thin on details of what the individual weather vane units would actually look like!
I have always been interested in wind motion objects, and have made a great number of both conventional weather vanes and what I call 'sculptural windbiles' in the past.
For the actual submission to the Paisley Street Sculpture Project, I had included images of past works, most replicas or interpretations of historic objects from the spread of history represented :
3) The Norse - ...Bronze Weather Boards like this element were fixed to the ship’s prow, with weighted ribbons moving to indicate wind direction and speed.
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| Copper Weatherboard - one of a set of four, early 1990's |
5) Quebec - The most common early Canadian weather vane is the rooster or cock.
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| Copper Weathercock, lightly sculpted, mid 1990's |
6) Upper Canada - As settlement moved westward into what is now Ontario, ... the Horse becoming one of the most popular.
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| Galvanized sheet steel, mid 1990's |
7) Into the Future - ... the spinning cups of the Anemometer, to measure wind speed.
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| 'La Tene Rotor', stainless steel, 2012 |
For other examples of past work see :
Weathervanes - http://www.warehamforge.ca/WEATHERVANES/wvane.html
Sculptural Windbiles - http://www.warehamforge.ca/DECORATIVE/windbiles/windbiles.html
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