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Ing. Karel Drbal - Patent File Number 91304


Republic of Czechoslovakia

Office For Patents And Inventions

Published August, 1959

Patent File Number 91304

Czech version (Česká verze)  

The right to use this invention is the property of the State according to Section 3, Paragraph G, Number 34/1957

Karel Drbal, Prague

Method of Maintaining Razor Blades and the Shape of Straight Razors.


Submitted 4 November, 1949(P2399-49)

Patent valid from 1 April, 1952


The invention relates to the method of maintaining of razor blades and straight razors sharp without the auxiliary source of energy. To sharpen the blades, therefore no mechanical, thermal, chemical or electrical (From an artificial source) means are being used. There are various mechanical sharpening devices being used till now to sharpen used razor blades. The blade is sharpened by crude application of sharpening material, which always results in certain new wear of the blade during the sharpening process. Furthermore, it is known that the influence of an artificial magnetic field improves the sharpening of razor blades and straight razors, if their blades lay in the direction of magnetic lines.

According to this invention, the blade is placed in earth's magnetic field under a hollow pyramid made of dielectric material such as hard paper, paraffin paper, hard cardboard, or some plastic. The pyramid has an opening in its base through which the blade is inserted. This opening can be square, circular, or oval. The most suitable pyramid is a four sided one with a square base, where one side is conveniently equal to the height of the pyramid, multiplied by p /2. [pi or 3.14/2] For example, for the height of 10CM, the side of 15.7 centimeters is chosen. The razor blade of straight razor is placed on the support made also of dielectric material, same as the pyramid, or other such as cork, wood, or ceramics, paraffin, paper, et. cetra. Its height is chosen between 1/5 and 1/3 of the height of the pyramid, this support rests also on a plane made of dielectric material. The size of this support should be chosen as to leave the sharp edges free. Its height could vary from the limits stated above. Although it is not absolute necessary, it is recommended that the blade be placed on the support with its sharp edges facing west or east respectively, leaving its side edges as well as its longitudinal axis oriented in North South direction. In other words to increase the effectiveness of the device it is recommended lie in essence in the direction of the magnetic lines of the horizontal component of the earth's magnetism. This position improves the performance of the device, it is not however essential for the application of the principle of this invention. After the blade is properly placed it is covered with the pyramid in such a way that its side walls face north, south, east, and west, while its edges point in north-west, south-west, south-east, and north-east direction.

It is beneficial to leave a new blade in the pyramid one to two weeks before using it. It is essential to place it there immediately after the first shave, and not the old, dull one. But it is possible to use an old one, if it is properly resharpened. The blade placed using the method above is left unobstructed until the next shave. The west edge should always face west. It improves the sharpening effect.


When this device was used, 1778 shaves were obtained using using 16 razor blades, which is 111 shaves per blade on the average. The brand used was "Dukat Zlato" made in Czechoslovakia. The lowest count was 51, the highest was 200. It is considered very easy to achieve up to 50 shaves on the average. (for a medium hard hair)

The following shows how the invention could save both valuable material and money: One razor blade mentioned above weighs 0.51 grams. We will consider 50 shaves on average when placed in the pyramid against 5 shaves when it is not. It is obvious that the number of shaves, degree of wear, and the ability to regenerate the dull edge depends on the quality of the material, quality of sharpening process, and hardness. ....given numbers are average and could be in fact much better. In the course of the year one therefore uses 73 razor blades without the aid of the pyramid while only eight razor blades while using the pyramid. Annual saving would be 65 razor blades or 33.15 grams of steel per person.

Only the pyramid shape has been used for this invention, but this invention is not limited to this shape, as it can cover other geometric shapes made of dielectric material that was used in accordance with the invention. And that this shape also causes regeneration of sharp edges of shaving blades by lowering of stresses and reducing the number of defects in the grids of crystal units, in other words recovering and renewing the mechanical and physical properties of the blade.

The Summary Of The Patent

1. The method of maintaining the razor blades and straight razor blades sharp by placing them in the magnetic field in such a way that the sharp edge lies in the direction of the magnetic lines. The blades are placed in the earth's magnetic field and are covered by the hollow pyramid made of dielectric material such as hard paper, impregnated or paraffin paper, cardboard or plastic. The most suitable is a pyramid with a square base. It is the best when one side is equal the height of the cone multiplied by p /2. [Pi or 3.14 /2] The pyramid is provided is provided with square, round, or rectangular opening in its base and is oriented with its side edges pointing to the north-west, south-west, south-east, and north-east directions. The  razor blade or straight razor is placed horizontally on the support made also of dielectric material, same as the pyramid or other such as cork, wood, paraffin paper, or ceramics, the height being height being between 1/2 and 1/3 of the height of the pyramid and which in turn rests on the plane made of dielectric material. The blade is positioned in north-south direction.

2. Method as article 1 and identified by the blade is placed in the cone, same side facing the same direction after each use.



Notes on the Great Pyramid Of Cheops:

Given: Height=146.6 meters

Base=230.4 meters

½ Base=115.2 meters

1) "....a four sided one with a square base where one side is conveniently equal to the height of the pyramid multiplied by p /2"(i.e.; pi or 3.17/2) The side of the pyramid is seen as the base length in architectural terms p (pi) is given as 22/7, as the ancients measured it. 230.4 meters = 146.6 x p /2. (pi divided by two)

2) The square root of the Golden Section of the ancients (expressed as 196/121) is equal to within three percent of error to the height divided by one half the base length of the Great Pyramid Of Cheops.

               a) H= 146.6 meters/.5(B)[115.2 meters]  =  1.272 meters    note: H= Height, B= Base




               b) f(phi) = 196/121

               c) Ö(The square root of) 196/121 = H/ ½ B or tolerance: + or - three percent.

3) The height of the pyramid divided by one half the base equals four divided byp (pi), p (pi) being 22/7.

               a) H/ ½ B= 1.272

b) 4/p (pi) = 1.270

4) From the known measurements of the structure, can we conclude that the architect of the Pyramid of Cheops knew the mathematical concepts of p(pi) and f(phi) ?


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