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Freitag, 4. Oktober 2013

On the bench-more steel!

 Currently there are a load of projects going on. The blades in the topmost picture are what we typically make at the Bethaus smithy on customer request, with a raw finish, a blade out of spring steel with a selective temper by edge-quenching, forged bolster / guard out of mild steel (file steel on request). They normally get a handle burned-to-fit and get peened over a copper buttcap. With those two, hot - punching the blade décor went a bit awry, so I kept them for myself.
 Top is a damascus Kopis with the squiggly bit;-) fallen off, so it will get some annealing and some new forging a squiggly bit. Next is a file steel blade that´s needing some forging still, and a Nessmuk and a hunting / steak knife out of ancient spring steel with a carbon content of about 0,75% and nothing else;-). Nessie´s already quenched (you can see the quench lines illustrating the technique quite well. For I always use a double quench technique. I heat the steel to the upmost part of the temperature window suitable for quenching. I wait until it is cooled in the air a bit and just right for quenching (you can use a magnet if you want to be sure). I quench the edge part very conservatively. When the temperature is coming down further to a dull red colour I put it in further. It is crucial that this part still isn´t magnetic! Then I take it out, while the spine still has some heat. I remove the scale and oil with a wet wire brush. When the edge part achieves a golden colour with cutting knives and a blue colour with cleaving knives, I put it in the oil to cool down. I then take a file and run it along the edge. It can have some grip, but must not bite, if that makes any sense. If it slides off completely, I use the heat radiance from the forge to bring down the hardness some more to enhance elasticity. After cooling down again, I repeat the file test and allow it to rest some. I then slam the edge against the edge of the anvil. It must not dent too much, best it shouldn´t dent at all. Then it has to carve iron rods. Next in line is a test of elasticity and shock resistance: I slam the flat blade over the horn of the anvil. If it breaks, it breaks. The next test is levering up a 30 kg anvil. If it survives all that, it´s ready to rumble;-). I will then remove any nicks or dents and put an edge to it. It has to cut paper in the least. Then I like to chop at least ten times into hardwood or antler to test the edge-holding capacity. Another good test is carving hardwood from the broad side. It has to stand up to those tests also and at least cut "any which way";-) through paper.

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