A project initiated many years ago which has finally come to fruition. A part of the Islandrovers Adventure Co. project, this is the first kotanto forged from rover steel, 1965 Series 2a Land Rover leaf spring steel, to be specific. This blade was crafted as a test of the forging and hardening properties of the steel, which seems to be listed as 60sicr8 steel and has not changed formulation since 1948 when the very first Series 1 Rover was built.
60sicr8 steel is suitable for applications that require high strength and durability, used for springs and other mechanical parts that are subject to heavy-duty operations and impacts, and in railway engineering, particularly in rolling stock for parts like bumper rings of railway wagons.
Having already skipped the first few stages of testing scrap steel for knifemaking due to its former use as a leaf spring, this knife was crafted at the museum forge. It began as a short section of leaf spring from a 1965 Series 2a Land Rover and was forged to shape in a charcoal forge using a hand hammer. Traditional swordsmith style yaki-ire gives it a very hard edge while maintaining toughness in the body. Finally, a simple vinegar etched finish removes the forge scale to reveal the character of the steel and the surface pitting from the decades it spent under a Land Rover traveling on adventures near and far.
After several tests of yaki-ire on this blade the main takeaway is that this steel performs best when the critical hardening temperature is as low as possible, a very dull red that is just above the point where it will not harden. This is generally always the best temperature but where some lower alloy steels are more forgiving when quenched at higher temperatures this particular one will tend to harden significantly above the clay line or even crack unless very careful heat control is observed. This deep hardening is likely a result of the manganese content and possibly affected by the high silicon content as well.
Ready for a day at the museum forge, the old 1966 Rover still earning its keep hauling tools overland at almost 60 years running (and on its original springs).
Opening the forge and preparing to unload the tools and steel.
A load of several hundred pounds of tools ready for a day at the forge.
This knife began as a section of leaf spring from a 1965 Series 2a Land Rover.
The springs were definitely nearing the end of their useful service life, removed from a vehicle that was undergoing restoration.
A hammer and cold chisel were used to separate the leaves of the spring.
The leaves are cut and sorted by size and condition with some requiring cleaning and preparation due to heavy pitting.
The selected piece for this blade will be used to test the forge-ability and hardening characteristics of this particular steel.
The charcoal swordsmith style forge with hand-powered wooden box bellows is used to heat the steel as it is forged.
View across the forge and out to the forest between heats on a cool and cloudy spring morning.
The steel has now been forged almost entirely to its final shape, including bevels, using only a hand hammer.
After heating evenly to critical temperature and cooling in air to normalize the grain a small amount of hand filing will form the notches and clean up the spine and tang, completing the profile.
A sen-dai (staple vise) holds the steel flat while the edge is adjusted with a file to an even 1mm thickness.
Finally the portion near the edge is smoothed with a coarse polishing stone.
A mixture of natural clay, charcoal powder, and polishing stone powder is prepared with water.
Adding the thin clay layer to delay the cooling of the body of the blade during yaki-ire (hardening).
Drying the clay over the flame in preparation for yaki-ire.
The steel is heated carefully in the forge to the lowest possible red-hot critical temperature and plunged into water to cool quickly. This blade has survived the stressful process of yaki-ire without cracking or warping.
Due to the differential cooling rates caused by the clay, the strip along the edge is now very hard while the rest of the blade remains tough and ductile, the best of both realms. A small amount of tempering is applied to release stress in the blade.
The blade will be coated with a thin layer of 100% natural tung oil and then baked at 300 degrees F (below the tempering temperature) to harden the oil into a durable protective coating.
Lunch break view towards the forge, toolboxes and tools must be onboard for whatever may be required on a given day.
Late fall sunlight still bright at midday but shadows are lengthening as the museum season comes to an end.
A segment of reclaimed copper pipe is annealed in the forge, the copper oxide giving a beautiful colour display.
A seppa (blade washer) blank is cut from the flattened annealed copper using hand shears. The opening for the blade is cut out with a small chisel and filed carefully to fit the tang.
After final fitting and coining the edge with a file in edo style the seppa will be ready for service.
A batch of subsequent Rover steel blades receiving various fittings in preparation for mounting.
The tang is constructed in a similar manner to a Japanese sword requiring only a single bamboo, horn, or hardwood peg to hold the knife assembly together. In addition to the sense of beautiful simplicity, this design allows the knife to be field stripped for cleaning, polishing, detailed cutting tasks, or major resharpening work.
The blade is 4″ long, the overall length is 7.25″, and the spine at the munemachi is about 6mm thick.
形 Katachi (geometry): hira-zukuri, slight iori-mune
刃文 Hamon (edge pattern): rising suguha
帽子/鋩子 Boshi (tip pattern): maru
中心/茎 Nakago (tang): funa-gata, ha-agari-jiri, no mekugi-ana
銘 Mei (signature): mumei (unsigned)
拵 Koshirae (mounting): none
Materials: reclaimed 1965 Land Rover series 2a leaf spring, reclaimed copper water pipe
This piece is in a private collection in Sweden.
Resources
Some helpful links for planning, designing, and crafting a handle and scabbard for an unmounted blade. Additional resources may be found via the search page, as well as scrolling down the process page, or in the tanto geometry archive.
