Abstract:
A hobby knife employs two threadably engaged forward and rear sections and a blade holder which mounts the knife blade for positioning generally outwardly from the front end. The forward section has a tubular shape with three angularly spaced longitudinal indentations which are traversed by a series of longitudinally spaced ribs. The forward and rear sections are substantially covered by overmold material.

Description:
BACKGROUND 
       [0001]    This invention relates generally to knives employed in hobby applications. More particularly, this invention relates generally to knives having an elongated handle and a knife blade extending forwardly from the handle. 
       SUMMARY 
       [0002]    Briefly stated, a preferred form of a hobby knife comprises an elongated handle having two threadably engaged forward and rear sections. A blade holder adjacent to the front end receives a knife blade for positioning generally outwardly from the front end. The forward section has a generally tubular shape with three angularly spaced longitudinal indentations. The indentations are traversed by a series of longitudinally spaced ribs. The forward section is rotatable relative to the rear section to clamp the blade holder against the received blade. 
         [0003]    In one embodiment, each indentation has a tapered, generally triangular shape. The series of ribs comprise ribs which generally decrease in angular length as their longitudinal distance from the front end increases. The forward section defines a rounded, triangular face. The rear section has the general shape of a cigar. The exterior surface of the front and rear sections are substantially formed by an overmold material. 
         [0004]    The front section has a tapered, central bore and the holder has a tapered exterior portion which longitudinally engages the surface of the bore to clamp opposed fingers of the holder against a received blade. The holder has a bifurcated rounded nose which extends from a threaded shaft. The rear section may have a threaded bore which is threadable with the shaft. The indentations are substantially identical and equiangularly spaced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is an exploded side view of a hobby knife and a protective cap; 
           [0006]      FIG. 2  is a side elevational view of the hobby knife of  FIG. 1 ; 
           [0007]      FIG. 3  is a bottom plan view of the hobby knife of  FIG. 2 ; 
           [0008]      FIG. 4  is a top plan view of the hobby knife of  FIG. 2 ; 
           [0009]      FIG. 5  is an enlarged front end view of the hobby knife of  FIG. 2 ; 
           [0010]      FIG. 6  is an enlarged rear end view of the hobby knife of  FIG. 2 ; 
           [0011]      FIG. 7  is a side elevational view of the hobby knife of  FIG. 1  with the cap mounted thereon; 
           [0012]      FIG. 8  is a perspective view of the hobby knife of  FIG. 1 ; 
           [0013]      FIG. 9  is a perspective view of a second embodiment of the hobby knife; and 
           [0014]      FIG. 10  is a side elevational view of the hobby knife of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    With reference to the drawings wherein like numerals represent like parts throughout the several figures, a hobby knife is generally designated by the numeral  10  in  FIGS. 1-8 . The hobby knife includes an elongated handle  20  which mounts a blade holder  30 . The blade holder  30  receives a blade  40  which projects and extends generally forwardly from the front portion of the handle. The blade holder  30  functions to firmly hold the blade  40  in a fixed position and to release the blade to permit replacement. A protective cap  12  is dimensioned to frictionally engage the handle  20  and cover the blade  40 . The cap  12  may be formed from a transparent plastic material. 
         [0016]    The handle  20  preferably has two sections  22  and  24  which are threadably connected, as will be described below. The rear section  22  is formed from a metal tubular member  26  which has an internal bore having an internal thread  28 . The top portion of the bore is enlarged to form a cavity  27 . A rubber overmold  46  is formed over the tubular member  26 . The tubular member  26  has a relatively small diameter to accommodate the overmold. Overmold  46  has a quasi-cigar type shape with a smooth contour and has a very soft outer feel. A preferred material composition for the overmold is a resilient polymer. Elastomers, synthetic rubbers and natural rubbers are suitable. The resilient polymer may also include other additives such as coloring agents, inhibitors, plasticizers, lubricating agents, filters, covering agents, reinforcing agents and other materials which provide striking and tactile qualities. 
         [0017]    The frontal section  24  comprises an overmold  50  which forms the exterior surface of the frontal section. The overmold  50  is formed around a central metal tube. The overmold  50  is preferably manufactured from the same material as overmold  46 . The tube includes a medial extension  52  which generally is received in the cavity of the rear section. With reference to  FIG. 5 , the front end  54  of the overmold has a quasi-rounded triangular shape with a smooth contour. 
         [0018]    Three equiangular spaced, substantially identical, side surface configurations  60  are formed in the overmold. The configurations  60  each include a longitudinally tapered quasi-triangular indentation  62  (relative to the rounded cylindrical surface) which converges rearwardly at a rounded smooth vertex  64 . The indentation  62  and, in particular, the vertex  64 , smoothly blends with the generally cylindrical principal portion of the overmold. A series of ribs  70  are closely longitudinally spaced and extend arcuately at a frontal portion of the indentation. The angular extent of the ribs  70  generally decreases as the position of the ribs from the front of the overmold increases. The ribs  70  provide a very efficient gripping surface for the user of the hobby knife. The overmold composition itself functions to provide a very tactile and soft feel for the knife. The surface configurations  60  and ribs  70  facilitate gripping and manipulation of the hobby knife. It should also be appreciated that the three overmold configurations  60  each provide a stable surface to prevent the hobby knife from rolling across a surface. 
         [0019]    The blade holder  30  includes a frontal bulbous nose  32  which is bifurcated to form a slot  34  between two clamp fingers. The holder includes a rearwardly extending shaft  36 . The shaft  36  has a relatively small diameter to accommodate the overmold  50 . The end of the shaft terminates with a threaded surface  38  which threads with the thread  28  in the threaded bore of the rear section. The holder portion includes a conical taper  44  adjacent the nose  32 . The shaft is receivable in the tube of the front section so that the nose  32  extends generally forwardly from the front surface. The extension is received in the cavity and the shaft thread  38  engages thread  28  to connect the sections  22 ,  24  together. 
         [0020]    A washer  48  may be preferably positioned between the intermediate ends of the front and rear sections to facilitate the tightening of the threaded engagement. 
         [0021]    The blade  40  has a shank  42  which may be received in the slot  34 . As the front section  24  is rotated relative to the rear section  22  for threading engagement, the conical surface  44  engages an inner cylindrical portion of the tube and forces the fingers to clamp against the received blade shank, to thereby firmly fix the blade  40 . 
         [0022]    It will be appreciated that the blade may be removed and replaced by counter-torquing the front section  24  relative to the rear section  22  so that the fingers are slightly loosened to permit disengagement of the blade from the holder. The sections are then re-torqued to tighten the blade in position at a fixed angular position relative to the central axis of the handle  20 . The overmold material and the forward surface configurations cooperate to facilitate the torquing/counter-torquing of the sections. 
         [0023]    With reference to  FIGS. 9 and 10 , an alternative embodiment of the hobby knife with a slightly different forward section shape is illustrated. In addition, the overmold of the rear section has a longitudinally sectioned form so that in the given embodiment, several overmold portions  82  and  84  may be provided of various contrasting colors. 
         [0024]    While preferred embodiments of the foregoing hobby knife have been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may be employed without departing from the scope of the appended claims.