Patent Application
20090163123
This invention relates to sanding blocks.
When performing repairs to an exterior of an automobile, surfaces must be carefully prepared to receive paint in order to avoid imperfections. Dents in body panels of an automobile are often repaired by filling them with a paste that subsequently hardens. The paste is then sanded to approximate the original contours of the body panel.
Body panels of automobiles can have a wide variety of shapes given the many models of modern and classic cars that exist. Sanding some body panels having complex contours in order to provide the proper shape and smoothness can be extremely difficult.
Sanding blocks are typically made to be used with industry standard straight line sanding paper, which has a width of 2.75 inches. The sanding paper may be attached to the sanding block by adhesion, Velcro® or other similar temporary attachment methods. Typically, sanding blocks are made so that the industry standard sandpaper fits onto the sanding block without having to cut the width of the paper. For instance, sanding blocks typically have a width of approximately 2.75 inches in order to accommodate the industry standard sandpaper.
One common sanding device is a wood block having a piece of sandpaper wrapped about its exterior. The wood blocks have flat surfaces and work well for sanding flat surfaces, however, they do not work particularly well for curved surfaces. The use of such common sanding blocks on curved surfaces often results in uneven sanding; mainly because such blocks are not bendable to the curvature of the surface being sanded, and because excessive pressure is often applied to some portions of the surface being sanded. Moreover, the application of excessive pressure may result in over sanding and rapid deterioration of the sandpaper, which, in turn, may damage the underlying surface.
In order to accommodate curved surfaces, sanding devices with a curved radius, typically a convex shape curve, are currently being used. The convex shaped blocks may be made from wood or a resilient material such as rubber. A user must use two separate blocks when sanding a surface that has both curves and flat areas, a first rectangular block for sanding flat surfaces and a second curved sanding device for sanding curved surfaces.
Recently, single blocks have been used that have one surface with a curved radius and another surface with a flat surface. However, this requires the sandpaper to be trimmed so that it fits both surfaces. This makes the single block difficult to use since a user would have to cut the standard sized sandpaper each time they wanted to replace the sandpaper on the block.
Therefore, there is need for a single sanding block that can be used to sand flat surfaces and curved surfaces without requiring a user to cut or modify the industry standard sized sandpaper to fit both surfaces of the sanding block.
In one aspect of the invention, a sanding block formed of a flexible material has a constant cross section along its longitudinal axis. The sanding block has a flat lower surface and a curved upper surface, the curved upper surface having an arc length about equal to the width of the flat lower surface. The width of the curved upper surface is preferably less than the width of the flat lower surface. The width and arc length are chosen to be about equal to standardized sizes for strips of sandpaper.
In use, sheets of sandpaper are secured to one or both of the flat lower surface and curved upper surface. Concave surfaces and convex surfaces having large radii of curvature may advantageously be sanded using the flat lower surface by bending the sanding block to conform to the surface. Concave surfaces having small radii of curvature may advantageously be sanded using the curved upper surface.
Embodiments of the present invention are directed toward providing a sanding block and a method of using the sanding block. Certain details are set forth below to provide a sufficient understanding of the invention. However, it will be clear to one skilled in the art that the invention may be practiced without these particular details.
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Sheets 26a, 26b of sandpaper can be secured to one or both of the curved upper surface 16 and flat lower surface 18. The sheets 26a, 26b preferably have a width about equal to the width 20. Furthermore, the width 20 of the flat lower surface 18 and the arc length 24 of the curved upper surface 16 may be chosen to correspond to standard sizes for sheets of sandpaper so that the sandpaper covers both surfaces 16, 18 to the edges. For example, in one embodiment a width of 2.75 inches corresponds to the standard width for strips of sandpaper sold in rolls. The width 20 and arc length 24 are preferably approximately equal to the width of the sheets 26a, 26b. In another embodiment, the width 20 and the arc length 24 are slightly smaller or slightly larger than the width of the sheets 26a, 26b. For example, the width 20 and arc length 24 may be less than the nominal width of the sheets 26a, 26b or exceed the nominal width by up to five percent of the nominal width. For example, the width 20 and arc length 24 may be less than the nominal width of the sheets 26a, 26b or exceed the nominal width by up to two percent of the nominal width.
The curved upper surface 16 and flat lower surface 18 are distanced from one another to provide a mass of material therebetween to be gripped by a user and to make the sanding block 10 somewhat rigid even though it is preferably formed of a flexible material. In one embodiment, the curved upper surface 16 and flat lower surface are separated from one another along their entire widths by an amount at least as great as one fourth of the width 20 of the flat lower surface 18, preferably greater than one third of the width 20. As noted above, longitudinal grooves 14 may be formed between the curved upper surface 16 and the flat lower surface 18. The grooves 14 may be formed between upper lateral wall portions 28a and lower lateral wall portions 28b. The upper lateral wall portions 28a may be separated from one another by a distance about equal to the narrower width 22 of the curved upper surface 16. The lower lateral wall portions 28b are separated from one another by a distance about equal to the width 20 of the flat lower surface. The distance 30 between the grooves 14 is preferably less than the narrower width 22 and the width 20. The lateral wall portions 28a, 28b are straight in the illustrated embodiment such that sharp corners are formed at the junction of the lateral wall portions 28a, 28b with the curved upper surface 16 and flat lower surface 18, respectively.
The curved upper surface 16 and flat lower surface 18 are preferably of equal hardness. For example, the sanding block 10 may be formed monolithically of a single piece of material, such as a polymer. The sanding block 10 is preferably formed of a material that is firm enough to enable a user to apply pressure along a substantial portion of the curved upper surface 16 or flat lower surface 18 when sanding. However, the material is also preferably flexible enough to allow the sanding block to bend along its longitudinal direction 12 in order to conform to curved structures. Materials having a Shore A hardness ranging from about 45 to about 90 have been found to provide such functionality. In a preferred embodiment, the sanding block 10 is formed of a polymer.
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While the sanding block of the present invention has been described in the context of the embodiments illustrated and described herein, the invention may be embodied in other specific ways or in other specific forms without departing from its spirit or essential characteristics. Therefore, the described embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
