As Sam mentioned, working both sides of the blade is key as is working the sections of the length of the blade, overworking one side will cause more material to become displaced and will result in offsets that cause bends and warps.
Something I do is to try to keep things as straight as possible through out all the forging steps, to do this, durring each heat, once the blade cools to the point where you can no longer move significant material, I always go and true up the edges and any off bits on the profile, etc with light blows before going into the next heat. This intermediate correction process helps keep the corrections small and keeps them from getting out of hand. Do not use heavy blows at these low temps however, working high carbons and alloys at too low of a temp will not make them happy and bad things like cracks will happen.
For straightening a blade that is warped and wavy along its ege, I usually sight down the edge, find a high spot, lay the high spot on the anvil and hit it lightly at its peak a few times (either at a black/dull red heat, or fully annealed), then flip and move onto the next. Once the major waves are corrected, I lay the blade flat on the anvil, or angled on the bevel, then starting at one end use light rapid blows while drawing the blade back across the anvil (thus moving the blows along the edge), then flip to the other side and repeat a few times until everything looks good, usually getting lighter and lighter on each pass. If there are any stubborn waves, individually knock them down.
For twisting along the blade length, I go to the vice.
|