Abstract:
A tool sharpening or dressing device provides a blade having a knife edge held within an aperture from below so that as the tool is drawn along a surface above the edge is able to trim the tool. The blade is clamped by a rotating washer with detent grooves to finely position the washer. The washer, in turn, pushes against the blade to position it.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to tool sharpening or dressing devices, and more particularly to a tool sharpening or dressing means having a positionable cutting blade and a guide for moving a tool relative to the blade so as to remove some material from the tool for dressing the tool&#39;s surface. 
     2. Background 
     Tool sharpening and dressing devices are well known in the prior art. These devices are used for sharpening knives, drill bits, and many other products that require either a keen edge or a dressed edge. Flexible plastic film sheet is commonly adhered to window glazing for various reasons. In the art of applying such film sheet a tool that is commonly used is a highly flexible doctor blade made of a rubber-like material. Such a doctor blade is pressed against the film sheet and drawn across the sheet to remove wrinkles and air pockets captured under the sheet. As such, such a doctor blade must have a dressed edge that is smooth and uniform. In use, such edges become nicked and cut so as to require re-dressing and re-sharpening. The present invention is well adapted for such, and may be used, as well, for a wide range of other applications. 
     The prior art teaches blade holders for cutting and dressing many kinds of tools. However, the prior art does not teach that such a blade holder may be adapted for finely positioning a cutting edge in a manner that is simple and inexpensive to manufacture. The present invention fulfills these needs and provides further related advantages as described in the following summary. 
     SUMMARY OF THE INVENTION 
     The present invention teaches certain benefits in construction and use which give rise to the objectives described below. 
     A tool sharpening or dressing device provides a blade having a knife edge held within an aperture from below so that as the tool is drawn along a surface above the edge is able to trim the tool. The blade is clamped by a rotating washer with detent grooves to finely position the washer. The washer, in turn, pushes against the blade to position it. 
     A primary objective of the present invention is to provide such an apparatus having advantages not taught by the prior art. 
     Another objective is to provide such an apparatus that is very inexpensive to manufacture. 
     A further objective is to provide such an apparatus where fine adjustment of the cutting edge is quite simply accomplished. 
     Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The accompanying drawings illustrate the present invention. In such drawings: 
     FIG. 1 is a perspective view of the preferred embodiment of the present invention showing a top side being used to sharpen a tool; 
     FIG. 2 is a perspective view thereof showing an underside of the invention; 
     FIG. 3 is a plan view of the underside thereof; and 
     FIG. 4 is a sectional view thereof taken along line 4--4 in FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The above described drawing figures illustrate the invention, a tool dressing apparatus comprising a rigid body 10 as shown in FIG. 2 preferably having a U-shape for improved rigidity. The body provides a planar surface 20 as shown in FIG. 1, the planar surface having an aperture 30 therein and, a pair of parallel guide surfaces 40A and 40B, the guide surfaces extending away from the planar surface 20 and approximately at right angles thereto. Preferably, the guide surfaces are functionally a part of respective guide ridges 42 as shown in FIG. 1. A blade support surface 50 is positioned adjacent to the aperture 30, the blade support surface 50 providing a cutting blade guiding means 60. The guiding means is preferably a pair of spaced apart elongated bumps as shown in FIG. 3. The apparatus further including a cutting blade 70 having a cutting edge 80, the blade fitting slidingly between the elongated bumps so as to maintain its orientation and attitude. A blade clamping means 90 such as a disk shaped element, is preferably adapted by its size and shape for rigidly holding the cutting blade 70 in the aperture 30 for dressing a tool 5 drawn along the rigid body 10 in contact with the planar surface 20 and also in contact with at least one of the pair of guide surfaces 40A,B. The blade clamping means 90 is further preferably adapted for moving the cutting blade 70 along the blade support surface 50 in a direction 110 (FIG. 3) corresponding to the cutting blade guiding means 60 to a preferred position in the aperture 30. 
     Preferably, the blade support surface 50 is placed at an angle, such as 10 to 15 degrees, relative to the planar surface 20 so as to position the cutting blade 70 at that same angle for enabling a preferred attitude of the cutting edge 80. Preferably the blade clamping means 90 provides a clamping surface 92 and a tensioning means 94 for biasing the clamping surface 92 against the cutting blade 70 for immobilizing the cutting blade against the blade support surface 50. The blade clamping means 90 is preferably the screw and tapped hole best shown in FIG. 4. If the material of which the body 10 is fabricated is soft enough, the screw may have a self tapping screw thread and may be merely installed within the body by rotation into a clearance hole. It should be pointed out that in FIG. 3, the blade clamping means 90 is omitted so that the several features on the blade support surface 50 may be seen, and so that several features of the blade clamping means 90 may be pointed out. 
     Preferably, the blade support surface 50 further provides a detent means 52 for adjusting discrete fixed positions of the blade clamping means 90 and the cutting blade 70 therewith. How this is accomplished will be described below. Preferably, the detent means 52 provides a plurality of ridges for accepting a first bump 54 which is integral with the clamping surface 92 of the blade clamping means 90 and shown in its typical position against the detent means 52 by a dashed circle in FIG. 3. The first bump 54 is positionable between any two of the ridges for establishing one of the discrete fixed positions of the clamping means 90 as it is rotated about the screw referenced by numeral 94. 
     Preferably, the blade clamping means 90 further provides a finger engagable protuberance 96 functional for moving the first bump 54 between the ridges as clamping means 90 is rotated about the screw. Preferably a second bump 98 is also formed integrally with the clamping surface 92 of the blade clamping means 90 and is positioned, as shown in FIG. 3 by the respective dashed circle, so as to contact the cutting blade 70 for positioning and for immobilizing the blade 70. This may be understood in that a force on the blade caused by the passing of the tool 5 will tend to move the blade 70 away from the aperture 30. Second bump 98 is a stop so that the blade 70 cannot so move. 
     Preferably, the parallel guide surfaces 40A,B are positioned at an angle relative to the cutting edge 80 so as to cause the cutting edge 80 to provide a shearing action against the tool 5 as it passes. Such an angle is advantageously about 80 degrees. 
     It should be clear that in use, the blade 70 is placed between the elongated bumps of the guide 60 and clamping means 90 is rotated until second bump 98 forces the blade 70 to assume a preferred position within the aperture 30. Screw 94 is tightened so as to insure that blade 70 is immobile. When the cutting edge must be further extended, it is accomplished by further rotating the clamping means 90 as shown by the arrows in FIG. 2. 
     While the invention has been described with reference to at least one preferred embodiment, it is to be clearly understood by those skilled in the art that the invention is not limited thereto. Rather, the scope of the invention is to be interpreted only in conjunction with the appended claims.