Friday, May 1, 2009

Simple knee cops part 2

The tuck points should be bent around until they are nearly vertical. These are particularly huge tucks, but they are spaced far enough apart to be able to get onto the horn of the anvil. In this case, I am using the horn of my armourer's anvil. (Rounded horns or balls just cause the tucks to open up.) The heel of an ordinary english anvil works almost as well. The idea is now to hit the rounded tuck down into the anvil, driving the metal upon itself, thereby shrinking it.

There are shrinking tools which can purchase or manufacture. I don't own one, but they incorporate vices which prevent the metal from squeezing out sideways when you whack the wrinkle in the middle. I just use the anvil like this. I only bring down the first centimeter or so, leaving the rest of the tuck nice and proud. I'll deal with it later, right now, I am just shrinking the edge. The goal here is to not smash the metal too hard into the just want to bring the wrinkle down against the surface, not cause it to spread out from the impact. Notice how those big tucks have turned into lumps and bumps?
The next step is to work the inside, popping the lumps and bumps out as required. They have a lot of stress in them, and they will easily "oilcan" outwards with a sharp rap with the hammer. I like to do this on the flat part of the wooden anvil...the wood doesn't scar the face of the metal like a steel anvil does.
You can't really see it in the picture, but the "peen" side of the ball peen hammer I am using is rounded to a 3 inch radius, and polished.

Some judicious working with the hammer will smooth out some of the lumps and bumps, and a couple of whacks in the middle will bring the centre up a little. Not really a lot of dishing...just enough to shape the metal. Dishing (smashing the metal down into a dent in the wood) thins the metal, so I don't do it too much. But on the other hand, there is no faster way to get the required profile.

Naturally, dishing causes some more wrinkles in the edge. I have a steel ball (2 inch diameter) which I bring these little wrinkles down by working from the outside. Alternatively, you can work over a surface plate or anvil face with a carefully rounded hammer....same difference. Because many of my readers don't have fancy balls and wheels, I recommend finishing this from the inside, with the workpiece resting on the flat wood of the anvil.
Why not the steel anvil? Well, the heartbreak of seeing all the scars and gouges in the surface of the anvil transfer to the workpiece usually puts paid to that idea. The extra time spent on the wooden anvil is recovered by the fact you won't need to sand the odd marks out of the workpiece when you are done.

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