Straightening a Twisted Blade

How to restore antique arms & repair practice swords.

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Scott M. Rodell
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Straightening a Twisted Blade

Post by Scott M. Rodell » Fri Mar 09, 2007 3:02 am

Philip-

After this week's Test Cutting training in Netherlands, it occurs to me that the common beginners error of rotating the wrist & sword (not maintaining proper edge angle) could result in a twisted blade. Can you please explain how to straighten a blade that has been twisted?

Philip Tom
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Post by Philip Tom » Mon Mar 26, 2007 12:31 am

Blade distortion caused by bad cutting technique (resulting in the blade getting stuck and the inertia of body weight creating excessive stresses) can take two forms: bending and twisting. The former has, I believe, been addressed in another thread.

Examine the blade to see if it is bent or twisted, or both. Sight down the edge and the spine (of a saber) or both edges (of a sword) as though aiming a rifle and you can tell what is the case. If both conditions are present, do your best to straighten the blade first, ensuring that it is as true as you can get it without any serious bowing or kinking.

For the twists, you will need:
1. Sturdy vise securely fastened to a heavy workbench that won't move easily.
2. Two pieces of wood, about 3/4 in. thick and a bit wider than the blade, just long enough to fit between the vise jaws. These need to be carved out to fit the blade snugly.
3. A sturdy piece of wood about 20 in. long, with a sawcut at midpoint just deep and wide enough to hold the blade securely. A 2x4 is good, you might want to shape the ends into rudimentary handles for ease of grip.

With a marking pen, locate the boundaries of the twisted area. The two pieces of wood should fit at the boundary that's closest to the guard. Clamp the blade between them, in the vise, with the blade horizontal. Place the saw cut of the other piece at the other end of the twisted area, and with both hands rotate in the desired direction with easy, gradual pressure to twist the blade back to its original straightness. Be careful not to jerk, or to apply sideways pressure -- rotate on the same axis.

Tempered steel tends to have a "memory" that enables a distorted section to regain its original shape with carefully applied, gradual force.

I would not advise using large wrench for the job (even with padded jaws) because there is the tendency to apply asymmetrical torque in such cases. It's better to apply the torque with both hands, working at 180 degrees position, to rule out sideways force that might induce a bend.
Phil

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