US 3699729 A
A sanding hand tool comprises an abrasive-surfaced strip of cloth in narrow endless belt form looped around a bow-shaped holding member of resilient metal having a convex rear surface on which a rear, reserve portion of the belt snugly fits and a concave front across which the remainder of the belt is exposed to provide an operative portion stretched under yieldable tension.
Description (OCR text may contain errors)
United States Patent Garvey et al.
SANDING HAND TOOL Inventors: Francis J. Garvey, Newfield; Bruce Winterbottom, Green Bank, both of Assignee: Carrier Craft Corporation, Newfield, NJ.
Filed: May 14, 1971 Appl. No.: 143,316
US. Cl ..51/391 Int. Cl. ..B24d 15/00 Field of Search ..51/358, 372, 381, 391, 392,
[ 1 Oct. 24, 1972  References Cited UNITED STATES PATENTS 2,132,889 10/1938 Ayres ..51/393 X 3,648,418 3/1972 Churchich ..51/392 Primary Examiner-Othell M. Simpson Attorney-Albert H. Kirchner  ABSTRACT A sanding hand tool comprises an abrasive-surfaced strip of cloth in narrow endless belt form looped around a bow-shaped holding member of resilient metal having a convex rear surface on which a rear, reserve portion of the belt snugly fits and a concave front across which the remainder of the belt is exposed to provide an operative portion stretched under yieldable tension.
7 Claims, 6 Drawing Figures PATENTEU 0m 24 I972 25 BRUCE WINTERBOTTOM ATTORNEY SANDING HAND TOOL The present invention comprises a sanding hand tool, particularly but not exclusively adapted for use in wood-working, and more especially provides a combination of abrasive strip and a holding member therefor constituting a handle device for mounting the strip with a portion of the abrasive surface exposed in operative position and the remainder held in reserve for ready exposure to operative substitution when required.
The device in a particular and preferred form of embodiment provides a tensioned strip of abrasive material, of the kind generally known as sanding cloth, in a holder in which it is readily mounted and released and replaced, with the exposed portion of the strip maintained yieldable for operative application to curved surfaces, such for example as the rounded areas of wood material to be sanded.
Objects of the invention are provide a tool of the character indicated which will be inexpensive to make, which will securely hold the sanding material in operative position and will readily free it for shifting to expose a new surface when required and will readily release it for replacement when worn out, and which will be essentially very simple in construction and reliable in use.
BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawing, illustrating a preferred embodiment of the invention,
FIG. 1 is a perspective view of the complete tool, comprising the combination of the abrasive element and the holding or handle member;
FIG. 2 is a detail top plan view of the central portion of the tool;
FIG. 3 is a longitudinal section taken on the section line shown in FIG. 2;
FIG. 4 is a cross section taken on the section line shown in FIG. 3;
FIG. 5 is a side elevational view of the tool shown in operative relation to the curved surface of a workpiece that is being sanded; and
FIG. 6 isa view similar to that of FIG. 5 but on a somewhat smaller scale, showing a modification.
DESCRIPTION OF THE PREFERRED EMBODIMENT In the preferred embodiment thus illustrated, the tool comprises two principal parts: the sanding or abrasive element 1 and the holding or handle member 2 on which the sanding element is mounted in operative position.
The sanding element 1 is an endless belt of abrasive cloth (or equivalent, such as non-woven plastic sheet material), having its outer surface 4 coated with sharp particles of flint, Carborundum Aloxite or the like. Such belts are commercially available in a number of sizes appropriate for the present purpose, being widely used as the abrading element of power sanders in which the belts are trained over vertically spaced driven and idler pulleys. A size that has been used with success in practicing the present invention is formed of a strip of 28 inches length and one inch width, with its ends spliced together to constitute an endless belt 1 which fits into cooperating relation with a holding member 2 of convenient size.
The holding member 2 is a strip of resilient or spring steel, in the present illustrative case one inch in width and slightly more than 28 inches, e.g., 28% inches, long. The strip is reversely bent on itself into bow shape, by turning opposite end portions 5 of the strip back at points 6, approximately 7% inches from each end, thus leaving a straight front portion 7 approximately 13 inches long between the points 6, 6, with the end portions 5 of the strip arched back into abutting engagement midway of the back are, at the line 8 in FIG. 3.
The abutting ends are secured together through the medium of a combined connecting and grip or handle element 10. This is a short length of metal which is formed generally in channel shape, some 3 inches long, with its longitudinal edges inwardly curved toward each other to form spaced apart side flanges 12, 12, spaced a half inch or so above the bottom of the channel. The bottom is cut crosswise along two lines a half inch or so apart in the central area of the element 10, and the intervening metal is struck up to form a bridging portion 14 defined by slots 16 open transversely of the element and just wide enough, and long enough, to admit the end portions of the strip, as best seen in FIGS. 2 and 3. With the ends abutted, a hole is drilled through the two ends, bisected by the end edges, so that each edge is notched by one-half of the hole, and a nut and bolt fastening 18 is set through the hole and an aligned hole in the bridge 14, so that the grip or handle element 10 and the meeting ends of the strip are securely held together.
The arrangement thus provides a holding member 2 for the sanding belt I which, prior to application of the belt, comprises a segmental shape made up of an arcuate back 5 formed by the two bent back portions and connected at the ends 6 by a straight length or front potion 7 which is related as a chord to the are formed by the back portion.
The longitudinal dimensions of the holding member 2 and the sanding member 1 are such that, in order to apply the sanding member to the holding member, the straight chord forming the front portion of the holding member must be bent or curved back into arcuate shape, by bringing the end points 6, 6 closer together, thus altering the originally segmental shape of the holding member (with a straight front chord subtending a rear arc) into the double arc or bowed shape shown in FIGS. 1 and 5. In this form, in which the holding member is maintained by the tension in the sanding member, the arc of the front portion 7 is on a considerably longer radius than that of the rear portion, with the result that the length of sanding element that spans the concavity or opening between the ends 6 of the holding member is stretched straight, under tension, as a chord to the newly formed are of the portion 7, as shown in FIG. 1.
It will be understood, of course, that the sanding element is installed on the holding member by the very simple operation of bowing the ends 6 toward each other sufficiently to permit the loop of the sanding ele- The tension by which the front portion of the sanding element is held between the end points 6, 6 is yieldable, with increased bowing of the holding member portions 7 and 5, 5, so that when the tool is applied to a workpiece, as shown at 22 in FIG. 5, the operative length of the sanding element will yield back into the concavity formed by the front bow of the holding element. Thus the abrasive surface is able to fit around a substantial area of a curved surface of the workpiece 22, as seen in FIG. 5.
It will be noted that the holding member is normally, prior to application of the sanding belt, static in the shape of a segment, with the front portion 7 a straight chord subtending the arcuate rear portion 5. The dimensions of this member of the combination are such, relative to the dimensions of the loop constituting the sanding belt, that the holding member must be deformed in order to be received into the looped belt. The deformation conssits in bending the front portion 7 inwardly, so as to transform the straight chord shape of that portion into an arcuate length of somewhat less curvature i.e., of longer radius, than that of the rear portion 5. The result is the stretching of the belt into true segmental shape, comprising a straight chord front portion, forming the operative area of the belt, which subtends an arcuate rear portion conforming exactly to the arcuate rear portion of the holding member.
It is to be understood that the dimensions and proportions given by way of example in the foregoing description of a preferred embodiment of the invention are merely illustrative and suggested, and not critical, so that they can be altered considerably within the principles of the invention and the scope of the appended claims.
FIG. 6 shows, on a somewhat smaller scale, a modification of the preferred form, differing therefrom principally in substitution of a simpler type of holding member. The modified member 24 is a single length of spring steel or equivalent, the same kind of material used in the preferred form, but as here shown is bent into a single are or bow, amounting substantially to the arcuate rear portion only of the holding member 2, lacking the front portion 7 thereof. This bow receives the holds the endless abrasive strip 26, just as the strip or belt 1 is mounted on the preferred form of member, and the member is similarly deformed into bow shape with the front portion of the belt stretched across the ends of the member as a chord subtending the arc, whose curvature is increased by the deformation. The ends of the member are best beaded inwardly to provide the rounded corners indicated at 25 in order to lessen the likelihood of the strip 24 being cut or damaged by the metal of the holding member, and the mounting belt is applied to a workpiece, shown at 27, in the same manner as the preferred form.
1. A sanding hand tool including a holding member comprising a strip of spring metal formed in generally elongated bow shaped,
and an endless belt of abrasive-surfaced material stretched around the holding member and constraining the member under tension so that the portion of the belt spanning the concave opening between the ends of the member is maintained in ten ion d is 'eldable rearward] into the concavity 0 the bo shape when pressgd against work being sanded.
2. A sanding hand tool as claimed in claim 1,
in which the strip comprising the holding member is continuous and forms a rear bow portion of arcuate shape of relatively short radius and a front bow portion of arcuate shape of greater radius.
3. A sanding hand tool as claimed in claim 1,
in which a grip or handle element is provided at substantially the central area of the rear of the holding member,
and said element has edge flanges curved inwardly over the edges of the member and spaced apart to overlap the side edges of the belt and hold the belt in place on the member.
4. A sanding hand tool as claimed in claim 2,
in which the ends of the strip forming the holding member are abutted at substantially the center of the rear bow portion,
and including a grip element clamping said ends together and forming a handle by which the tool may be held in use.
5. A sanding hand tool as claimed in claim 4,
in which the grip element comprises a short length of metal providing a slot receiving the ends of the strip and having longitudinal margins curved over the strip,
and including fastening means standing through the ends of the strip and the grip element securing the grip element in place.
6. A sanding hand tool comprising the combination of a holding member and a sanding element,
said holding member comprising a resilient metal strip formed into the shape of a segment having an arcuate rear portion subtended by a straight chord front portion,
and said sanding element comprising an endless belt of flexible strip material having an abrasive surface on one side and being adapted to be looped over and around the holding member, and being so dimensioned relative to the holding member as to require deformation of the holding member chord into concave curvature in order to receive the belt, whereby the sanding element mounted on the holding member forms a segmental shape in which an operative portion of the element is stretched as a straight chord subtending an arcuate portion extending around the arcuate rear portion of the holding member.
7. A sanding hand tool as claimed in claim 1,
in which the holding member is a single length of spring metal formed in the shape of an open bow having the belt stretched around it and providing a straight chord portion extending between the free ends of the member and subtending the arc thereof.