Sharpening...

[Rational Root]

Sharpening
Having a miserable cold, and being able to do feck all, I tried sharpening up a few chisels. It's theraputic. Back and forward, back an forward, change up a stone, repeat.

Of course we all know the Back of the chisel is the important part for sharpening. Here's a simple idea to make it a little easier to hold the chisel steady and flat on the stone, and make life a lot easier on your fingers.

Just whip a pencil onto the chisel as shown with heavy string. Every second loop, go around the pencil and change direction - this locks the pencil in place.
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Two whippings 1 1/2 inches apart is about right.
You just can see in this picture, a low spot just at the business end of the blade (top as you look at the picture). It will never be sharp until I get down to that spot. One thing that helps is only flatten the last inch.
http://3.bp.blogspot.com/_-jLgHzfXWAU/SSNFoqsXMwI/AAAAAAAAAsA/tmv0zHTcVbc/s320/IMG_0265.JPG
The traditional test it shaving hairs off the back of your arm. For those who think that's a myth.... Dada.... Real Live Arm Hairs

http://1.bp.blogspot.com/_-jLgHzfXWAU/SSNFovWFQqI/AAAAAAAAAsI/4lhz37rBfcI/s320/IMG_0257.JPG

I used DMT (no I don't work there :rolleyes:) diamond whet stones. Including the XXCoarse, Coarse, XFine and XXFine, and a dirt cheap carpenters pencil !!!

[Pete E]

Thanks, another good idea.

[Jay Greer]

Forgive my comment but, in flattening the backs of Japanese chisles and plane blades, we use a wider block on the back of the tool and no binding other than the hand. This distributes the pressure over the full width of the blade which, is flattened on a steel plate using carbarondom dust and a drop of water. As the work progresses the powder is pulverized more and more until the tool has a mirror finish on the back. I can see that the narrow pencil allows too much pressure on the forward end of the tool and not enough on the back. Once flattened, the hollow ground backs of Japanese tools are not subjected to the process again as it will destroy the hollow grind.

[Rational Root]

Jay, your comments are always welcome.

I think I follow what you are saying, but if the block is not bound to the tool, do you move the chisel around by it's handle and simply use the block to apply downward pressure ?

I was mostly using the pencil to move the chisel back and forward on the stone so that I did not accidentally lift the handle. The weight of the handle tends to lift the blade, but when I support the handle, if I am not paying attention, I can lift the handle too much....

Dave.

Forgive my comment but, in flattening the backs of Japanese chisles and plane blades, we use a wider block on the back of the tool and no binding other than the hand. This distributes the pressure over the full width of the blade which, is flattened on a steel plate using carbarondom dust and a drop of water. As the work progresses the powder is pulverized more and more until the tool has a mirror finish on the back. I can see that the narrow pencil allows too much pressure on the forward end of the tool and not enough on the back. Once flattened, the hollow ground backs of Japanese tools are not subjected to the process again as it will destroy the hollow grind.

[Jay Greer]

Dave,
The block needs to be the full width of the blade. I never use any binding to hold the two together. One hand grasps the blade and handle and the other applies the pressure. Other wise the narrow block, such as the pencil, allows the pressure to rock under the palm causing one edge to recieve more pressure than the other. This is also caused by the, extended, fulcrum of the arms as the blade moves away from the body. So,
the other trick is to be as much over the sharpening plate as possible. This is why the Japanese craftsmen, "Shokonin", kneel on the ground or use a very low bench. This allows the full weight of the upper body to be directly over the sharpening surface.
Jay

[Rational Root]

I had not considered pressure being different across the blade. I had only considered the pressure from the tip to the handle.

So much to learn, so little time. :(

Dave,
The block needs to be the full width of the blade. Other wise the narrow block, such as the pencil, allows the pressure to rock under the palm causing one edge to recieve more pressure than the other. This is also caused by the, extended, fulcrum of the arms as the blade moves away from the body. So,
the other trick is to be as much over the sharpening plate as possible. This is why the Japanese craftsmen, "Shokonin", kneel on the ground or use a very low bench. This allows the full weight of the upper body to be directly over the sharpening surface.
Jay

[Jay Greer]

I had not considered pressure being different across the blade. I had only considered the pressure from the tip to the handle.

So much to learn, so little time. :(
It has taken me many years to learn the secrets of tuning Japanese tools, which I use almost exclusively in my work. The tuning techniques apply to western tools as well. Tool backs must be dead flat in order to allow the wire edge to be removed. Any lifting of the handle, during flattening, will cause a rounding off of the back making, the tool less efficient. However, it just dawned on me as to why it might be better to bind the block and tool together, as you do, for sharpening western blades. It keeps the block from sliding off of the blade, which is not concave on western blades.
In the case of Japanese chisel and plane blades, the tools are forged to an ergonomic shape. The face of a Japanese blade is forged rough and is slightly concave as is the back of the tool. This hollowing allows the blade to be held more comfortably. The hollow grind on the back is there to allow full pressure to be applied to the bevel edge without having the fingers contact the water stone, which results in bloody fingers!
Jay

[Rational Root]

I tired the lapping plate and carbarondom dust, and it worked very well, but it's quite messy.

The DMT stones are clean enough to use in the kitchen without risking a "frying pan divorce".

One thing that I found was a buffing wheel on an arbour on my drill with some polishing compound will take the edge from "cuts a few hairs and scratches my arm" to " shaves cleanly, removing every single hair with ease".

[Ron Williamson]

You can also buff using a piece of MDF that has the compound rubbed onto it.
R