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Patent rights are available for this new knife
sharpening system -- contact M. Carbone

Patent number 6,805,619 -- Knife sharpening system

A BRAND NEW IDEA IN KNIFE SHARPENING -- A KNIFE AND KNIFE
SHARPENER THAT ARE MADE PRECISELY FOR EACH OTHER.

We call it the "Parallel Track Knife Sharpening Set" and will be using
" P'Track " as a trademark.

This P'TRACK (tm) system essentially allows the user to move the
sharpening stone in a precise curved or flat plane through contact
with (1) the blade and (2) the rails, which are on a lower plane than
the blade and spaced at an uniform distance from the blade. This
forces the stone to contact the blade at the exact angle which is
set by the fixture. 

THE BASIC P'TRACK (tm) IDEA WORKS WITH ANY STRAIGHT OR CURVED
KNIFE -- even serrated knifes. The drawing shows how the system works
with a curved blade.

Scroll down for more information.

A prototype of the sharpener. This particular serrated knife has been used for years to efficiently cut corrugated cardboard

The following is from the Patent Office website:

United States Patent 6,805,619 / Carbone / October 19, 2004 / Knife sharpening
system

Abstract
A knife sharpening system for sharpening blade edges of knives. The knife sharpening
system includes a base portion having an elongate guide rail having a top surface at a
first level, a knife support for maintaining a blade of a knife being sharpened with its
blade edge spaced apart by a horizontal distance from the guide rail and for elevating
the blade on a plane at a second level which is higher than the top surface of the guide
rail. A sharpening implement that is longer than the distance between the guide rail and
the blade edge is provided, and placed on the blade's edge and the guide rail, and is
moved thereacross to sharpen the knife edge.

Inventor: Carbone, Martin R. (Santa Barbara, CA) / Appl. No.: / 909353 / Filed: July 18, 2001
Current U.S. Class: 451/164 ; 451/356; 451/367; 451/557
Field of Search: 451/162,163,349,371,164,356,367,557

INVENTION DISCLOSURE -- This is to disclose a P'TRACK (tm) Knife Sharpening System

BACKGROUND --
1) Knives have been used and sharpened since prehistoric times
2) No system has ever been available whereby the angle of factory sharpening for a
particular knife has been able to be maintained by an unskilled person.
3) Hand sharpening at too steep an angle has always dulled the knife because the
edge of the knife was partially removed.
4) Hand sharpening at an angle that is not steep enough has always accomplished
nothing because the edge of the knife was essentially untouched by the sharpening
device.

THE P'TRACK (tm) INVENTION is hereby described. It is made up of;
(1) A flat plate of wood, plastic or metal, approximately 5" x 16" x 3/4" thick . 
(2) A cradle/holder to hold the knife to be sharpened in a flat horizontal position.
(3) One or two 1/8" thick metal guide rails, each parallel to the edge of the knife blade
and approximately 1" from the edge of the knife blade. One guide will be on the right
side and the other guide will be on the left side. The blade will be sharpened on one
side using one rail and then turned over. The other side will then be sharpened using
the other rail. For serrated knives or other knives that require sharpening on one side --
only one rail will be used
(4) A hand held sharpening surface -- approximately 1/2" wide and 3" long with a handle.
This can be any regular sharpening stone. The handle for the stone is not shown in the
photos above
(5) The flat plate, the cradle holder and the knife will be made and sold as a set whereby
the elements of the set will be matched to one another and will not be interchangeable
with parts from other sets.
(6) In the case of knives that have straight (not curved) edges and the same width and
thickness as each other, the cradle holder and guide rails of any knife of length "A" will
be able to be used with any knife smaller in length than "A" when they both have the
same handles.

THE P'TRACK (tm) METHOD -- 
1 The knife is sharpened by machine at the factory to a predetermined edge angle.
2 When it needs sharpening, the knife is placed by the buyer/user in the cradle/holder
3 The metal P'TRACK (tm) guide rails are fixed in position in the flat plate such that they
are parallel to the knife edge and 1" from that edge.
4 The guide rails are fixed at a predetermined vertical height, such that when the flat
sharpening surface is placed perpendicular to the rail and the knife edge and across
the gap between the rail and edge, the angle formed between the sharpening surface
and the knife edge will be exactly that angle to which the knife blade was sharpened at
the factory.
5 The flat hand-held sharpening surface is placed across the gap between (a) the knife
edge to be sharpened and (b) the guide rail -- in an approximately perpendicular position
to each supporting edge.
6 The sharpening surface is moved across the knife edge and rail in any motion pattern,
keeping in contact with the edge of both the guide rail and knife edge.
7 The knife is turned over and the process as in #2 to #6 above is repeated for the second
side.
8 If the knife is of the type where only one side is to be sharpened --- step #7 is eliminated. 

ADVANTAGES OF THIS INVENTION -- This invention makes it virtually impossible to place
the sharpening device at anything other than the exactly correct sharpening angle.

DISADVANTAGE OF THE P'TRACK (tm) SYSTEM -- In general, except as noted above, every
knife shape will have to have a sharpener made for that particular shape and the knife and
sharpener will have to be purchased as a set. This will add to the cost of the purchase. We
assume the market will ultimately tell us if a significant number of users are willing to pay
somewhat more for a knife they can keep perfectly sharp to factory standards.

FURTHER -- 
1 In the manufacture of serrated knives, the serrations are usually put on one side of the blade
at a certain angle. The other side of the blade is usually flat. In the case of such a serrated knife,
it is virtually impossible to sharpen the entire cutting surface of the knife completely -- (although
the system described above will sharpen the points of the serrations effectively) .
2 Serrated knives that will be made to conform to the system herein described will be factory
sharpened on the side opposite the serrations to an angle that will result in a 1/16" flat sharpening
surface on that surface which is normally flat over the width of the blade. This will enable this
system to work with serrated blades.
3 This system can be easily applied to chisels and scissors and virtually any other cutting tool.

KNIFE SHARPENERS NOW ON THE MARKET --
Virtually all knife sharpeners have at least three parts -- (1) a sharpening surface, (2) a holder for the
sharpening surface and (3) a holder for the knife blade. Sometimes the user is the holder for either
the sharpening surface or the blade. And sometimes the user holds both the sharpening surface
and the knife. 

In all designs, there is either a (a) sharpening surface against which the knife blade is moved or (b)
a fixed blade against which the sharpening surface is moved.

When it is being used, at any one moment, the sharpening surface is in a certain plane but it can
either be fixed or it can rotate, translate or oscillate in that plane. 

In general knife sharpeners now on the market either have (a) a fixed sharpening surface set at
some angle or (b) an adjustable sharpening surface designed to be set at a certain angle for a
particular knife. Most adjustable units are arranged so the sharpening surface can be held at any
one of five or six preset angles. The very popular Lansky Rod Sharpener and others like it are
examples of this type.

The popular Chef's Choice power driven sharpeners are an example of a fixed angle sharpening
surface. That sharpening surface oscillates, but always stays set at a fixed angle. The user moves
the blade (with the help of a magnetic guide) against this fixed angle. This particular sharpener has
three sets of sharpening surfaces -- the very coarsest is used to grind the knife being sharpened to
an angle that works with the other two much finer sharpening surfaces. This feature means you can
use the sharpener with any knife you have or will buy by essentially regrinding the knife to match the
sharpener. It seems to me it would be more efficient over all if knives were sold that were ground at
the factory to match the angles of this sharpener.

Some sharpeners have an infinite number of settings and the sharpening angle can be set at any
angle. This of course has the disadvantage in that you can never be sure that you are setting the
angle at the exact angle you used the last time for the knife at hand. Any good machinist knows
that it is is practically impossible to set any cutting tool exactly without either (a) having fixed stops
or (b) making a series of trial cuts and taking measurements after each cut. The new system proposed
here does away with any adjustment on the theory that all adjustments are a source of trouble and
their elimination is important.

STRAIGHT CUTTING EDGES. --
Knives that have a straight cutting edge are relatively easy to sharpen at a fixed angle. All that is
needed is that a sharpening tool with a flat plane surface (a stone, grinding wheel or sanding belt)
which is held against the blade and either the stone or the blade is moved so the sharpening surface
stays in contact with the entire length of the blade. The sharpening tool can, but does not have to,
rotate, oscillate or vibrate in its plane while it is contacting the knife.

SOME THOUGHTS ON CURVED KNIFE BLADES --
On curved knife blades, note that the sharpened surface does not lie on a flat plane -- it lies on a
curved plane. If we accept (a) the fact that the sharpened edge of a curved knife lies in a curved
plane and (b), from basic geometry, the fact that the intersection of two flat planes is a straight
line, we can see that any sharpener where the sharpening surface is held in a fixed flat plane,
that sharpener will not be able to sharpen curved blades effectively. In other words, if a sharpening
surface is held in a flat plane and rubbed against a knife which is essentially a flat plane -- the
resulting sharpened surface must be a straight line and that system can't sharpen a curved knife.

In order to sharpen a curved blade at a given angle from handle to tip -- the stone must be held at the
given sharpening angle along the entire length of the blade. If the angle between the blade and the
sharpening stone changes -- it seems obvious that the sharpened angle must change and the desired
angle will not be maintained throughout. This simple fact seems to have been missed by essentially all
sharpening tools to date.

The same principle applies to any curved blade. That is, when sharpening any curved blade, either (a)
the blade must be rotated around the center point of a curve -- where that curve is the same curve as
the knife blank at the point of sharpening, or (b) the sharpening surface must be rotated to achieve the
same relative motion as (a).

In most knives (excepting circular knives) the curve of the knife blade is not constant and is variable
from point to point along the blade. That means the rotation in (a) and (b) above must always vary to
match that varying curve of the blade.

Therefore, to sharpen a curved knife blade at a constant sharpening angle, either (a) the blade must
be rotated around constantly varying center points or (b) the sharpening surface must move along a
constantly varying angular path while it is at the desired sharpening angle to the blade

The P'TRACK (tm) system presented here allows the sharpening tool to move along the path described
above in (b). I do not believe any other simple system does this. Automatic sharpening system in factories
achieve the motion that is needed by various complicated methods that move the blade precisely through
the needed motion pattern. The method presented here achieves the complicated motion by a simple
arrangement that requires no moving parts.

PROFESSIONAL KNIFE MAKERS invariably follow plan (a) above -- they rotate the blade of a curved knife
against a sharpening surface that is fixed in the sharpening plane (although vibrating, oscillating or
translating in that plane). It is not as hard to do that as it might seem -- all they have to do is watch (or feel)
the sharpening line between the blade and the sharpening surface and keep the line perpendicular to the
plane of the sharpened surface at the point of contact. Once they start sharpening, the blade wants to follow
the correct sharpening path as described above and if the knife maker varies from that path, he or she will
immediately feel added pressure which induces them to back off to the proper angle. It is somewhat like
steering a bicycle. Once you are moving along a certain line, the bicycle tries to stay on that line and if you
try to move the handlebars, you will feel a pressure inducing you to keep the handlebars in the proper position.

IN FACTORIES, if a constant sharpening angle is desired either the sharpening surface or the blade must be
rotated out of a flat plane if the sharpened surface is to be a curved plane. That is quite a problem and is usually
solved by an intricate mechanical system. The P'TRACK (tm) sharpener and knife set presented here solves
the problem simply by the use of a set of rails (one for each side) that are parallel to and equidistant from the
blade. As long as the user can keep the sharpener approximately perpendicular to the blade, the sharpened
surface will be a perfect curved plane. By the way, if the user does not keep the stone perpendicular to the
blade, this does not hurt the sharpening process (it does slow it down somewhat) because that lack of
perpendicularity pulls the stone away from the sharpened edge and the user will be somewhat rounding
the back edge of the sharpened area. Some sharpening experts claim that a rounded sharpening area behind
the edge is very beneficial in that it adds strength to the sharpened edge.

THIS IS NEW -- BUT NOT REVOLUTIONARILY  NEW -- We are not claiming we have invented the only method
to sharpen knives. All sharpeners hold the knife and the sharpener in some position relative to each other. I
am reasonably certain that others skilled in the art know that to sharpen a curved knife surface either the blade
or the sharpener must move in a curved plane. We only claim our P'TRACK (tm) method is the only system that
allows the average person to sharpen knives to a professional edge.