Forging San Mai How close to shape do you forge?
Posted 25 September 2011 - 06:55 AM
Posted 25 September 2011 - 11:14 AM
As the maker you have to be able to develope a vision of the intended blade and that includes the pattern and size. Once you have it welded, you are free to draw it out as you like, but here is the thing that will make it look right. You mentioned it already. Forge it evenly. Try to keep the pattern centered up in the blade. You will get a feel for it, but sometimes you may have to let it cool off during the forging process and grind off the scale and check it by dipping it in acid to actually see the pattern. If you have'nt gone too far with your forging, there might be opportunity to make corrections if need be.
Forging evenly. How do you do that? Besides the obvious, you should take into consideration that while you are hammering one side of the blade, the other is against the anvil and cooling faster. I try to hammer one side, then go back into the forge and then hammer the other. I try to keep the heat within a range, not allowing the blade to get close to being too cold. So, even heating, similar hammering techniques and patterns of progression along the blade as they relate to each side, is important.
Posted 25 September 2011 - 08:16 PM
Lin gave some great advise and as he said, you have to develop a vision of the finished piece. If you draw what you would like your finished blade to look like (especially where the transition line is where the 2 materials meet), it will help you answer the questions on how much forging you need to do.
The more you forge in the bevels and distal taper, the closer the transition (line where the 2 materials meet) will be to the edge.
The above diagram illustrates this. Each diagram has the 3 pieces and the darker lines represent the bevels of the blade converging at the cutting edge (everything on the outside of the darker lines represents what will be ground off). The image on the left would be a stock removal and the right would be the bevels forged very close to shape. You can see from this how you have control of the outcome by forging. Similarly, you should also be able to get a feel for how the thickness of each material can have an effect on the outcome.
Posted 26 September 2011 - 06:16 AM