Posted by: woodbeecarver   in Knives, Tu Tor Plus, Tutorials

Two Blade ShapesTwo Blade Shapes

Carving on the Edge is to imply that the cutting edge of the carving knife blade is what separates the wood fibers while removing a chip.  The cutting edge, when magnified will reveal minute cutting teeth much like a hand saw.  It is these cutting teeth that create the cutting action when the knife is used in a slicing action.  The slicing cut is to follow the path of the cutting edge through the wood so that as many of the cutting teeth are utilized. In conjunction with the cutting edge teeth, the bevel on the side of the blade be it skinny or fat, provides the angle at which the cutting edge enters the wood.  So it is both the slicing action and the angle of the cutting edge that work together to create a clean cut.

The typical and traditional carving knife blade has a straight cutting edge as in a wharncliffe and sheep foot blade shape.  The straight cutting edge is most efficient when used in a slicing action which requires that the cutting edge travel in a skewed direction into the wood.  A perpendicular position of the cutting edge to the wood results in a wedge cut which is forcing the cutting edge into the wood breaking wood fibers rather that cutting the fibers.  Illustration # 1 shows the “wedge cut” while Illustration # 2, # 3 and # 4 show the “slicing cut” as it moves through steps 1, 2, and 3 of traveling along the cutting edge.

Wedge CutSkewed Slice  Push Stroke SlicePull Stroke Slice

The best illustration of both actions is to picture the old timers who sat on nail kegs on the porch of a general store carving fine and curly shavings off a cedar stick.  The goal was to start at the top of the stick and slice as thin of shaving as possible the full length of the stick without it breaking loose.  The curly shaving was then thrown up in the air and the whittler would blow under the shaving to keep it aloft because it was light as a feather.  To accomplish this feat of whittling the old timers had discovered that if the blade was skewed in the slicing action they could control the fine shaving to complete length of the stick.  If however the knife blade was perpendicular to the wood, then as it was pulled down the stick it would either dig into the wood or exit the wood without creating a fine shaving the entire length of the stick.  It was the skewed position of the blade that allowed for the most efficient slicing action of the cutting edge as the knife was pulled along the path of the stick’s length.

Another illustration is slicing a loaf of bread.  Forcing the knife blade straight down in a wedge cut through the loaf of bread when the knife is perpendicular across the top of loaf is to squash the bread before it is cut. On the other hand, when the knife slices across the top of the loaf, the slicing action will cut the bread efficiently.

 Another illustration, the guillotine became a more efficient means of execution over the broad axe of the axe man executioner because the guillotine’s blade was skewed along its cutting edge which created a slicing action as it slide down the blade guide of the guillotine as opposed to the wedge cut of the axe that used the force and muscle of the axe man executioner.

Other illustrations include cutting steak, a paper cut, or the slicing cut of carving knife across the carver’s thumb while carving.  Slicing is the key to the most efficient use of a carving knife.

With the typical and traditional carving knife blade with a straight cutting edge, the blade almost always needs to be skewed to allow the cutting edge to slice through the wood.  The straight edge cannot reach into every area of the carving project to do a slicing cut resulting in forced wedge cuts and stop cuts followed by angled cuts of only the tip end of the blade.  Such cuts are using only a small portion of the cutting teeth which does not create a clean and even surface.

A curved cutting edge is more efficient in creating a slicing cut in both the push and pull stroke of the carving knife through the wood.  Carving on the edge is to following the direction of the cutting edge in the slicing motion. A straight cutting edge only slices on the straight while the curved cutting edge slices on the curve.  The curved cutting edge can reach into areas where the straight cutting edge cannot. A curved cutting edge can create “soft” surface cuts imitating the result of a gouge carving tool. A curved cutting edge can cut clean notch cuts because it uses more of its cutting teeth with its curved cutting edge.

Slice and Roll CutCurved Cutting Edge

The curved cutting edge is most efficient when using a Slice and Roll action in either the push or pull stroke. This Slice and Roll action is following the curvature of the cutting edge when pushed or pulled through the wood.  The Slice and Roll action can be used with a straight cutting edge knife but with a shorter radius and more “tear out” of wood fibers than cleanly cut fibers.

Slicing Notch Cut                 Slice and Roll  Slice and RollSlice and Roll

The most efficient cut is a slicing cut and the most efficient slicing cut is accomplished with a curved cutting edge knife blade. Learning to slice with every cut does take some practice to get over using the wedge cut or short forced cuts.  Learning to Slice and Roll with a curved cutting edge takes some practice to get used to the feel of the action but once learned the Slice and Roll and the curved cutting edge will become a favorite in the carving journey that will set the carver free to be more creative with the various ways a carving knife can be used.

“Slice with the cutting edge,” is a good motto for all knife carvers to remember and to do for a more satisfying carving experience for Carving on the Edge.






This entry was posted on Monday, December 9th, 2013 at 3:55 pm and is filed under Knives, Tu Tor Plus, Tutorials. 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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