31
May

SHARP CAN BE SHARPER – Sharpening Knives by Hand

   Posted by: woodbeecarver   in Knives

“Wood carving is more the journey than the destination,” and an important part of that journey is learning to sharpen one’s carving knives.

There is no magic formula or method as each have their own way of sharpening.  However the “KEY” is to practice to develop what works at this particular time and place on the journey because sharpening is an ever learning process that will be improved upon further down the wood carving journey. 

Another rule I follow is “The only right way is if it works for you.” Practice and practice to discover what works for you and then use it until further practice opens another way to sharpen that works a little better.

When I started out carving seriously in the early 1970’s I had one small oil stone that belonged to my Grandpa Bill.  Because it was called an oil stone I assumed oil needed to be applied to the stone.  I had observed old time farmers sharpen their pocket knives by moving the blade in a circular method over the stone, working one side and then another.  Occasionally they would test the sharpness by trying to shave hair off their arm which supposedly was to indicate sharpness.

As to establishing a bevel it was widely recommended to lay the blade flat on the stone and then raise the back edge up twelve degrees or the thickness of a dime and then concentrate sharpening the edge which would produce a noticeable bevel along the cutting edge.  Once sharp the knife was to be stropped on a piece of leather, be it an old belt, the side of a leather boot or even using the palm of one’s hand as “Uncle Remus” did in the “B’er Rabbit” stories.

Not knowing what I was doing, I assumed that the knife was sharp as I could shave hair on my arm and pull shavings off a piece of wood.  As time went on with repeated sharpening experiences, reading about sharpening and listening to others explain how they sharpened their knives, little by little the process changed through trial and error experimentation.

I discovered that a blade with a less noticeable bevel  seemed to carve easier and appeared to be sharper.  Then I discovered that oil was not necessary on the stone while sharping making the sharpening process a little quicker.  All that was necessary was to occasionally clean the black residue off the stone with mineral spirits.  Andy Anderson in his book, “Carving Characters in Wood,” used his sharpening stone dry without oil or water, which was an encouragement to experiment on a dry stone and it worked.

As the sharpening journey continued I learned that a carving blade carved sharper if the side of the blade was flatted from the back edge to the cutting edge without any noticeable bevel except for a micro bevel that occurs during the stropping process.  Through trial and error with the mechanics and physics of moving the blade across the abrasive stone it was discovered that if the cutting edge was skewed as it was pushed and pulled in a slicing action across the stone that a more even sharpening of the  cutting edge occurred.

During the same process it was learned that instead of picking up the blade at the end of each pass and returning to the starting place that it was difficult to keep the blade flat on the stone.  So the process is to keep the blade flat on the stone with the cutting edge at a skewed angle while slicing into the stone and simple rub the blade back and forth in order to create a flat plane on the side of the blade.

STONE SHARPENING SYSTEMKey to learning came the recognition to use several abrasive stones with progressive finer abrasiveness.  The sequence finally was determined through expirementation to start with a medium grit carborundum stone to flatten the sides of the blade until a “burr” edge was well established on the cutting edge.

 

The next step was to use a fine India stone continuing to keep the blade flat on the stone rubbing back and forth making the scratches on the side of the blade smaller and making the “burr” edge finer.

The third step was to use a Soft Arkansas Stone continuing to keep the blade flat on the stone rubbng back and forth making the scratches on the side of the blade smaller still and making the “burr” edge finer still.

The fourth step was to use a Hard Arkansas Stone and repeat the same process as the previous steps.  The side of the blade became mirror like and the “burr” edge was so fine it could barely be seen.  In all the steps of using the stones the cutting edge of the blade sliced into the stone.

The final step is to strop the blade across a strip of leather by dragging the cutting edge backwards across the leather strop, picking the blade up with each pass and stropping the other direction.  This is continued until the “burr” edge is rubbed away. Often it is in this stage of removing the “burr” edge that a very fine “wire edge” will come off revealing the true cutting edge.  Continue stropping several more times after the “burr” edge is no longer visible because “sharp can be sharper,” and a little more stopping will slick-en up the side and the cutting edge.

To test sharpness is to cut across the end grain of the piece of wood that would produces a curl of a chip and a shiny surface after the blade has passed through the cut.  When the knife is used in a slicing action, the cutting edge separates the wood fibers and the slick and mirror polished sides of the blade burnish the wood as it passes through the cut leaving a clean and slick surface that sparkles like a diamond.

This was the method  used for many years but as I said about the journey continuing to teach us another way, I have discovered that using “diamond sharpeners” works just as well, maybe even a little better than the sharpening stones.  At least “diamond sharpeners” are more convenient to carry with you and don’t wear or break if dropped.  Using a series of photos utilizing ‘”diamond sharpeners” the process will be explained once again in a “show and tell” fashion.

DIAMOND SHARPENERSIn this photos two types of diamond sharpeners are displayed:  the smaller version on a plastic handle and the credit card size sharpener.  Notice that there are four brands featured to indicate that one is not any better than the next.  Abrasiveness is graded in coarse, fine, super fine or by numbers 200 – 325 (coarse) 400 (medium) 600 (fine) and 1200 (super fine).  The # 1 indicated the beginning position of the knife on its journey across the diamond sharpener. The next three photos will show # 2, #3, and #4 to show the positions of the knife in its journey back and forth across the sharpener.

DIAMOND SHARPENERSDIAMOND SHARPENERSDIAMOND SHARPENERS

In the photos the diamond sharpener being used rests on a flat and thin piece of wood that has a strip of rubberized mesh drawer liner that grips the back of the metal credit card diamond sharpener so that it will not slide around.  For safety purposes the sharpening stick should rest on a table or work bench and not on one’s knee as a knife can slip off the diamond sharpener.  That is a painful lesson I learned along the journey, so keep in mind the Old Boy’s Law: “You don’t learn anything the second time you are kicked by a mule.”

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LEATHER STROPAfter using the super fine diamond sharpener the next step is to strop the cutting edge on a leather strop impregnated with chrome oxide or similar abrasive compound.  The blade is held at a skewed angle and pulled backwards the full length of the strop.  At the end of the journey pick the blade up and go back to the top and start again continuing several times.  This is illustrated in photos #1 and #2.  The other side of the blade is stropped as illustrated in photos #3 and #4.  Stopping continues long after the burr edge and wire edge has been stropped away remembering that “sharp can be sharper.”

LEATHER STROPLEATHER STROPLEATHER STROP

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LEATHER STROPLEATHER STROPFLEX CUT STROP

The photos above show various sizes of home made strops made by gluing leather onto a thin and flat strip of wood and applying chrome oxide abrasive compound.  The final photo show commercially made strop by Flex Cut with their abrasive compound.  While continuing on the wood carving journey of continuing to learn how to keep your knives sharp always remember, “Sharp can be sharper.” I know because I am continually learning that lesson over and over every time I sharpen a knife.

This entry was posted on Saturday, May 31st, 2008 at 8:46 pm and is filed under Knives. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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