US 3831279 A
A tool for cutting a strap from the edge margin of a piece of leather or like material. Two rigid bars that are supported in spaced apart relation by a cutting blade at one end and an adjustable spacer at the other end. Blade clamps on each bar support both ends of the blade. A handle having an opening in which the bars are clamped and a guide surface to engage the edge of the leather sheet. The handle has a releasable clamp to permit adjustment of the distance between the blade and the guide surface. The opening in the handle is sufficiently large that angular adjustment of the blade relative to the guide surface is possible.
Description (OCR text may contain errors)
United States Patent 1191 Burns Aug. 27, 1974  STRAP CUTTER FOR LEATHER AND LIKE 3,080,652 3/l963 Martinez 30/283 MATERIAL 3,552,016 l/l97l Hittepole 30/294  mvenwr' 25 31 32 Prirnary Examir er-Al Lawrence Smith Assistant Examiner-J. T. Zatarga Filed! J 1973 Attorney, Agent, or Firm-Thomas H. Olson  Appl. N0.: 368,322
 ABSTRACT U-S. A tool for cutting a Strap from the edge margin of 3 30/294 piece of leather or like material. Two rigid bars that are upported in paced apart relation a cutting Field of Search 30/278, 280, 293, 1 blade at one end and an adjustable spacer at the other 30/287, 283 end. Blade clamps on each bar support both ends of the blade. A handle having an opening in which the References Clted bars are clamped and a guide surface to engage the UNITED STATES PATENTS edge of the leather sheet. The handle has a releasable 207,597 9/1878 12111011 30/293 clamp to Permit adjustment of the distance between 247,306 9/188] Chapman 30/293 th ad and the guid urf The p ning in the 961,643 6/1910 Pierce 30/293 handle is sufficiently large that angular adjustment of 1,463,312 7/1923 Dillinger 30/293 the blade relative to the guide surface is possible. 2,559,29I 7/1951 2,648,905 8/1953 Hinsche 30/293 X 13 Claims, 6 Drawing Figures STRAP CUTTER FOR LEATHER AND LIKE MATERIAL This invention relates to a cutting tool for cutting The force necessary to move a cutting blade through flexible material such as leather in order to cut the leather is proportional to the thickness of the blade. A thinner blade requires less force that is subject to breakage. The present invention substantially eliminates blade breakage by providing a cutting tool that supports the blade at both ends so that the advantages of employing thinner blades even on leather that is thick and stiff can be realized.
The specific embodiment of the invention that is disclosed in more detail hereinafter includes a pair of rigid elongate bars. The bars at one end are provided with a blade clamping mechanism and at the other end with an adjustable spacer so that the: bars can be supported in parallel spaced apart relation. After the space between the bars is adjusted in accordance with the thickness of the leather to be cut, the tool is moved along the leather and the blade cutting edge, which is disposed between the bars, cuts the leather. Because the blade is supported from both ends by the respective bars, it is substantially immune to breakage. A handle for drawing the tool through the leather is provided and the handle is longitudinally adjustabe on the bars toward and away from the blade to provide a width gauge for cutting straps from the edge margin of the material.
A feature and advantage of the present invention is that the cutting edge of the blade is substantially confined to the space between the bars so that the likelihood of injury to the user of the tool is virtually eliminated.
Another feature and advantage of the present invention is that the bars and the blade cooperate to support one another. That is to say the blade spaces one end of the bars apart by a distance dictated by the thickness of the leather to be cut and the bars protect and support the blade as stated above.
Yet another feature and advantage of the present invention is that the handle, in addition to providing a hand grip and a width gauge, also tends to support the two bars with respect to one another so that the space therebetween is preserved at the preset amount.
Still another feature and advantage of the present invention is that the above mentioned handle is so proportioned that it can be conveniently gripped by the hand, and the fingers of the hand gripping the handle can be used to assist in guiding the leather in its traverse of the slot between the bars.
A further feature and advantage of the present invention resides in the placement of the blade in the space between the bars at a slight angle to the direction of relative movement between the tool and the leather so as to maintain the edge of the leather against the guide surface of the handle. In certain thick leathers such offset is neither needed nor desired, and the construction of the handle of the present invention affords simple positioning of the blade in a position parallel to the direction of the cut.
Other objects, features and advantages of the present invention will be more apparent after'referring to the following specification and accompanying drawing. in which: I
FIG. 1 is a perspective view of a strap cutter according to the invention;
FIG. 2 is an end view of a strap cutterv according to the present invention;
FIG. 3 is a top view of a strap cutter-accordingto the present invention;
FIG. 4 is a side view of the strap cutter'according to the present invention;
FIGS is an exploded fragmentary view of a portion of FIG. 2; and
FIG. 6 is a fragmentary view showing a modification of the present invention for use in cutting pieces of stiff material.
Referring more particularly to the drawing, reference numerals l2 and 14 indicate respective elongate rigid bars which in one structure designed according to the invention are formed of maple pieces having a length of approximately 6 inches. Mounted adjacent one end of the bars is a cutting blade 16 having a sharp cutting edge 18 which is on the downward side of the blade as viewed in FIGS. 1, 3 and 4. Each bar 12 and 14 is provided with facilities for securing the blade in spanning relation of the space between the bars. Such securing facilities include a slot 20 cut partially through the bars so as to leave a web section 22. Screws 24 are threaded into each of the cross bars in the portion thereof inward of slot 20 as at 26 in FIG. 2. Outward of the portion threaded .in at 26, screw 24 is provided with machine screw threads and the portion of the bar outward of slot 20 is drilled at 28 to clear such latter threaded portion. Threadedly engaged with such outer threaded portion is a nut 30 which is provided with a suitably roughened or knurled portion so that the nut can be turned with,
the fingers and without employment of tools. Thus it will be seen that when nut 30 is tightened slot 20 is closed and the portions of the cross bar that define the slot thereby grip the surfaces of blade 16. Web portion 22 is sufficiently narrow that, even though the cross bars are of relatively rigid material, a degree of flexure exists so that the slot can be opened and closed to disengage or engage the blade.
Because the blade 16 is supported at both ends,
blades of 0.010 inch thickness can be used without breakage. This is in contrast to certain prior art cutters in which blades supported at only one end have a thickness of up to 0.040 inch to afford adequate strength. Employment of a thinner blade, as is possible with the present invention, reduces the force needed to cut the material.
As can be seen most clearly in FIG. 2, screws 24 are placed at an angle of approximately 5 to the longitudinal axis of bars 12 and 14. This positions the roughened portion of nuts 30 out of the path of the leather that is disposed in the space between the bars to avoid scratching the surface of the leather.
Bars 12 and 14 at the ends thereof opposite blades 16 are provided with an adjustable spacing mechanism that includes a spring member 32 which in one device designed according to the present invention is formed by a neoprene cylinder which is compressible and which biases the cross bars away from one another. For so compressing spring member 32 there is a thumb screw 34 having a threaded shaft 36 which engages into a threaded member 38 mounted in bar 12. Threaded member 38 is a commercially available device sold under the trade designation T-nut". Bar 14 is provided with a clearance hole 40 for screw 36 so that when the screw is engaged in threaded member 38 and through the central opening in spring member 32, tightening of the screw will compress the spring member and permit an adjustment of the space between bars 12 and 14. Because of the resilience of the spring member, such spacing once established will be maintained until intentionally changed.
For affording a hand grip on the cross bars and blade assembly, there is a handle structure 42. Handle structure 42 defines adjacent one end thereof a rectangular opening 44 which is sized to admit cross bars 12 and 14 therethrough. Longitudinally outward of rectangular opening 44, the handle structure is axially bored to accommodate a clamping screw 46 which has a threaded shaft that engages in complemental internal threads in a T-nut 48 which is located at the end of the bore within opening 44. The inner end of clamping screw 46 contacts a rigid clamping plate or slug 50 which as seen most clearly in F IG. 4 has a width corresponding to the width of rectangular opening 44. Plate 50 has a central depression 51 into which the end of clamping screw 46 fits to assist in aligning the plate within opening 44. When screw 46 is tightened the clamping plate 50 is urged downward, as viewed in FIG. 4, so as to clamp bars 12 and 14 between the clamping plate and the opposite face or bearing surface 44' of rectangular opening 44.
For assisting in the alignment of bars 12 and 14 within opening 44, the inner face of clamping plate 50 is provided with a projecting abutment 52 which is spaced from the left edge of clamping plate 50 and the left edge of opening 44, as viewed in FIG. 4, by an amount slightly greater than the thickness of bar 12. The purpose of abutment 52 is to position bar 12 as shown in FIG. 4 and to allow bar 14 to move within the rectangular opening in accordance with the adjustment of the space or slot between the bars 12 and 14. Accordingly, when clamping screw 46 is loosened, handle structure 42 can be moved along bars 12 and 14 toward and away from blade 16 and when a desired position is attained the handle structure can be there retained by tightening clamping screw 46.
Handle structure 42 has a surface 54 facing blade 20; surface 54 thus acts as a guide or gauge surface to establish the width of straps to be cut from the edge margin of a piece of leather or like material. Surface 54 is excised along a cylindric path indicated at 56 to relieve the intersection between the surface and the upper surface of rectangular opening 44 so that the leading edge of the leather passes such intersection without interference. With reference to FIG. 3, leading Corner C of a sheet of material S is spaced from the upper edge of opening 44 so that the tool can be moved downward with respect to the sheet identified by reference character S.
Handle member 42 includes at the end thereof opposite rectangular opening 44 a hand grip 58. The shape and size of hand grip 58 is important in maximizing the utility of the tool. With reference to FIG. 3 the tool is typically used by gripping the hand grip portion 58 with the right hand and the leading edge of sheet S with the left hand. Because of the size of hand grip 58 the fingers are clear of the lower portion of surface 54 (designated at 54' in FIG. 4) and the finger tips of the right hand can support sheet S from the bottom thereof. More specifically, the height of hand grip portion 58, i.e., the distance between extremities 60a and 60b in FIG. 4, is such that the heel of the hand is engaged at extremity 60b and the finger tips engaged at extremity 60a, so that guide surface 54' is not covered by the fingers, but rather, is exposed for engagement by the edge of sheet S. To achieve this advantageous characteristic the distance between extremity 60a and 60b is at least about l inches and ideally about 1% inches. Such dimension is sufficient that an adequate grip on the grip portion 58 can be had without requiring that the fingers totally circumscribe the handle and obstruct guide surface 54. The hand grip portion 58 also includes a reduced height region 62 so that the outwardly sloping surface intermediate region 62 and extremities 60a and 60b further enhances the degree of engagement between the hand of the user and handle structure 42.
As seen in FIG. 3, slot 20 is not parallel to guide surfaces 54 and 54' but is sloped inwardly in a direction rearward of cutting edge 18 of blade 16. In practice, the angle of slots 20 with respect to guide surfaces 54 and 54 is about 2, a greater angle being shown in FIG. 3 solely for the sake of clarity of illustration. The angle of the blade causes a force to be applied to edge E of the cut and therefore urges the outer edge of the sheet into intimate contact with guide surface 54. Thus the accuracy of the width of the strap cut from the edge margin of sheet S is enhanced.
For cutting thick and stiff materials, e.g., oak-tanned leather, the 2 slope of blade 16 is not needed to secure a straight cut and, in fact, may necessitate the application of inordinate force to draw the blade through the leather. Because the longitudinal dimension of rectangular opening 44 exceeds the width of bars 12 and 14 (See FIG. 6) a shim 64 can be placed between one wall of the rectangular opening and the cross bars to bring slot 20 and blade 16 into parallelism with guide surface 54. Shim 64 can be constructed of any suitable material having a thickness appropriate to position blade 16 at the desired angular relationshipwith respect to guide surface 54. In one device designed according to the invention, a piece of thin cardboard was employed with success for shim 64.
In cutting narrow straps or laces from soft leathers it is frequently desirable to have a greater angle between blades 16 and guide surface 54. To achieve this, shim 64 is placed on the opposite side of rectangular opening '44 so that virtually any angle between the blade and the guide surface can be achieved.
In operation of the present invention, clamp screw 46 is first loosened so that the space between bars 12 and 14 can be adjusted in accordance with the thickness of the material to be cut. To achieve adjustment of the space so that it is only slightly greater than the thickness of the material to be cut, one of nuts 30 is loosened to permit blade 16 to slide within the slot 20 that is associated with such loosened nut. The end of the bars at blade l6=is then moved to the desired spacing and the nut is retightened. Screw 34 at the opposite end of the bars is then manipulated to bring the bars into parallelism, the force stored in spring member 32 serving to maintain the bars in that position. The distance from guide surfaces 54 and 54' to blade 16 is adjusted by moving the bars within opening 44 and when the desired position is obtained clamp screw 46 is tightened to lock the bars in that position. The presence of abutment 52 serves to guide the assembled bars within opening 44 to facilitate the adjustment thereof until clamp screw 46 is tightened. The tool is then grasped in the right hand as described above and the leather sheet S is grasped in the left hand. The edge margin of the leather sheet is placed against guide surface 54 and the tool is moved toward the user while theleather is simultaneously moved away from the user. Because of the slope of blade 16 the edge margin of the leather is maintained against guide surfaces 54 and 54 so that an accurate constant width strap is cut from the edge margin of the sheet. Because of the circular cut out portion 56 in guide surface 54, the leading edge comer C of the leather sheet will not inhibit movement of the tool with respect to the leather. Should it be desired to cut stiff leathers a shim 64 is inserted as shown in FIG. 6 and explained in more detail hereinabove.
When it is desired to replace blade 16, both nuts 30 are loosened in order to open slots in both bars 12 and 14. The blade can then be readily removed and a new one inserted, after which nuts are retightened.
Thus it will be seen that the present invention provides a strap cutter for materials such as leather and the like which is adjustable to accommodate virtually all requirements, and which has a thin blade that permits strap cutting with the application of less force than is feasible with other devices intended for the same purpose. Because blade 16 is supported from both ends, the likelihood of breakage of the blade is reduced or eliminated. Because the blade resides between bars 12 and 14, it is inaccessible to the users fingers so that the likelihood of injury to the user is significantly reduced. Because the space between bars 12 and 14 is adjustable, the cutter of the present invention can be adapted to accurately cut straps from virtually any thickness and/or stiffness of leather.
Although one embodiment of the invention has been shown and described, it will be obvious that other adaptations and modifications can be made without departing from the true spirit and scope of the invention.
What is claimed is:
1. Apparatus for cutting straps from the edge margin of a sheet of flexible material comprising first and second rigid elongate bars, a cutting blade mounted adjacent a first end of said bars and extending between said bars, said bars having means for supporting said blade in spanning relation of said bars, said blade in cooperation with said supporting means acting to space said bars from one another at said first end, said bars each having a second end opposite respective said first ends, means for spacing the second ends of said bars from one another so that said bars are mutually parallel and define a material guiding slot therebetween, and a handle mounted on said bars and having means for affording adjustment of said handle longitudinally of said bars toward and away from said blade, said handle having a surface generally transverse of said bars to form a gauge surface spaced from said blade.
2. Apparatus according to claim 1 wherein said second ends spacing means comprises a compression spring member intermediate said bars, said compression spring member and said bars adjacent the second ends having holes therethrough, and a threaded member disposed in last said holes for adjustably compressively loading said compression spring member.
3. Apparatus according to claim 1 wherein said blade supporting means comprises a pair of confronting surfaces for defining a slot in each said bar adjacent the first end thereof, said slot having a width corresponding to the thickness of the blade, and means for drawing said confronting surfaces toward one another to frictionally engage the blade.
4. Apparatus according to claim 3 wherein said slot is disposed at an angle of about 2 with respect to said gauge surface, the extremity of said slot that corresponds to the cutting edge of said blade being more remote from said gauge surface than the opposite extremity of said slot.
5. Apparatus according to claim 3 wherein said drawing means comprises a threaded member having an inner portion threaded into said bar inward of said slot, a mid-portion extending through said slot, and an outer portion extending through said bar outward of said slot to the first end of the bar, the bar outward of said slot having a clearance hole for said threaded member, and a nut threadedly engaged on said threaded member for bearing against the first end of the respective bar so that said confronting surfaces are drawn together in response to tightening said nut.
6. Apparatus according to claim 5 wherein said threaded members reside at an angle to the longitudinal axis of said bars so that said nuts are exterior of the planes of said bars that define the material guiding slot.
7. Apparatus according to claim 1 wherein said handle includes a rigid elongate body defining a rectangular opening that extends transversely thereof, said opening being of sufficient size to admit said bars therethrough, said opening being boundedby a bearing surface, a clamping plate disposed in said opening, and means for moving said clamping plate toward and away from said bearing surface to engage and disengage said bars between said bearing surface and said clamping means.
8. Apparatus according to claim 7 wherein said clamping plate moving means comprises a portion of said rigid body opposite said bearing surface defining a threaded bore, the axis of said bore being substantially normal to said bearing surface, and a threaded member engaged in said threaded bore and having an inner end for engagement with said clamping plate and an outer end exterior of said rigid body, said outer end having means affording a finger grip on said threaded member for turning said threaded member to move said clamping plate toward and away from said bearing surface.
9. Apparatus according to claim 7 wherein said clamping plate includes an abutment projecting toward said bearing surface by an amount less than the width of said bars, said abutment being spaced from an edge of said clamping plate by a distance corresponding to the thickness of said bar so that said first bar is constrained within one transverse boundary of said rectangular opening.
10. Apparatus according to claim 7 wherein said rectangular opening has a dimension longitudinally of said rigid body sufficient that a spacer shim can be inserted intermediate said bars and one side of said bearing surface to position said blade at a range of angles relative said gauge surface.
11. Apparatus according to claim 7 wherein said body is excised at the intersection between the gauge ing a maximum dimension in a direction parallel to the plane of said lateral region sufficient that frictional contact between the hand of the user and the handle portion can be had without obstructing said lateral region.
13. Apparatus according to claim 12 wherein said maximum dimension is at least about 1% inches.