Abstract:
A holder for marking material includes a housing and a collet which moves axially in the housing. The housing has a first side wall and a second side wall opposite the first side wall. Cavities having sloping surfaces are formed in the housing first side. The collet includes an arm having wedges formed on its outer surface and positioned to be received in the housing cavities. The collet is movable between an extended position in which the sloped surface of the housing cavities engage the collet arm wedges to urge the collet arm transversely towards the housing second wall to frictionally grip the marking material in the holder and a second position in which the wedge is received in the housing cavity such that no transverse force is applied to the collet arm, and the marking material can move freely relative to the holder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not Applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    This invention relates generally to holders for soapstone markers, and, in particular, to a soapstone holder which allows for easy advancement a stick of soapstone as the soapstone stick wears down.  
           [0004]    Soapstone is often used as a marker to mark various materials. Soapstone marking sticks are commonly provided in lengths of about 5″ and have cross-sectional dimensions of about 0.2″×0.5″. Soapstone sticks are fragile or brittle, and, are easily broken during use if not held in a protective holder. Such broken sticks are often too small for further use, and hence are discarded. Various holders have been designed to protect soapstone sticks to prevent breakage of the sticks during use. However, such prior holders have drawbacks—they are expensive to produce, difficult to use, and do not allow for easy advancement of the soapstone stick as it wears down.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    Briefly stated, a holder for marking material is provided which is simple to assemble and operate, and which allows for the gravity feed of the marking material to advance the marking material in the holder. The holder is a two piece assembly which includes a housing and a collet which moves axially in the housing. The housing is hollow and open at its opposite ends. It has a first side wall and a second side wall opposite the first side wall. At least one, and preferably two or more cavities are formed in the housing first side. The cavities each have a sloped outer surface, and at least one of the cavities includes a shoulder which extends from the cavity sloped surface to the inner surface of the first wall. The second side wall has an inner surface shaped to correspond generally to the shape of the marking material.  
           [0006]    The collet includes a body and an arm extending from the body. The collet is sized such that the at least a portion of the collet body extends from the top of the housing, and the collet arm extends from the base of the collet body substantially to the opposite end of the housing. The collet arm has an inner surface and an outer surface. The arm inner surface is shaped to correspond generally to the shape of the marking material. The arm has at least one wedge, and preferably two or more wedges, formed on its outer surface and positioned to be received in said housing cavities. The collet is movable between an extended position in which the sloped surface of said housing cavity engages the collet arm wedge to urge the collet arm transversely towards the housing second wall to frictionally grip the marking material in the holder and a second position in which the wedge is received in the housing cavity such that no transverse force is applied to the collet arm, and the marking material can move freely relative to the holder.  
           [0007]    The holder also includes a biasing element to bias the collet to the extended position. The biasing element is preferably a spring which has a generally S-shape. The spring has a first end in contact with a base of the collet body and a second end which engages the housing. The housing includes an opening, and, the spring includes a finger at its second end. The spring finger is received in the housing opening. Preferably, the spring is integrally formed with the collet. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a cross-sectional view of an illustrative embodiment of a soapstone holder of the present invention, showing the holder gripping a length of soapstone;  
         [0009]    [0009]FIG. 2 is a cross-sectional view similar to FIG. 1, but showing the holder being activated to allow for advancement of the soapstone stick;  
         [0010]    [0010]FIG. 3 is a side elevational view of the soapstone holder;  
         [0011]    [0011]FIG. 4 is an end elevational view a housing for the soapstone holder;  
         [0012]    [0012]FIG. 5 is a perspective view of the housing;  
         [0013]    [0013]FIG. 6 is a top plan view of the housing;  
         [0014]    [0014]FIG. 7 is a perspective view of a collet for the holder; and  
         [0015]    [0015]FIG. 8 is a top plan view of the collet. 
     
    
       [0016]    Corresponding reference numerals will be used throughout the several figures of the drawings.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0017]    The following detailed description illustrates the invention by way of example and not by way of limitation. This description will clearly enable one skilled in the art to make and use the invention, and describes what I presently believe is the best mode of carrying out the invention. Additionally, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.  
         [0018]    A soapstone or marking material holder  10  is shown generally in FIGS. 1 and 2. The soapstone holder  10  includes a housing  12  which is generally in the shape of a hollow rectangular tube. The housing  12  receives a collet  14 . In FIG. 1, the holder  10  is shown with the collet  14  in a retracted position, in which the collet clamps a soapstone stick  16  in place in the holder to prevent advancement of the soapstone. In FIG. 2, the collet is shown in an extended position in which the collet does not grip or clamp the soapstone stick, and in which the soapstone stick can be advanced under the force of gravity. The holder is sized to receive a standard stick of soapstone. Such soapstone sticks are typically 5″ long; and are rectangular in end elevation with dimensions of {fraction (3/16)}″×½″. Thus, the holder has an overall length of about 6″, approximately the length of a typical pen or pencil, and is sized, for example, to fit within a shirt pocket. It will be appreciated that the holder can also be sized to accommodate soapstone sticks that have cross-sectional dimensions of {fraction (1/16)}″×½″ or {fraction (3/32)}″×½″. Also, it can be sized and configured to receive soapstone sticks that are ¼″ in diameter. Although described for use with soapstone sticks of the noted dimensions (which are the more common dimensions for soapstone sticks), the soapstone holder of the current invention can be configured to accept soapstone sticks of any desirable cross-sectional configuration.  
         [0019]    The housing  12  includes a top wall  20 , a bottom wall  22 , and side walls  24  and  26 . The housing  12  has opened ends  28  and  30 . The holder includes a clip  32  on its bottom wall  22  to allow the holder to be clipped, for example, in a shirt pocket. The side wall  26  includes two sloped sections  34 . The sections  34  each include a sloped inner surface  36 , and end in a shoulder  38  which is substantially perpendicular to the inner surface  40  of the side wall  26 . A third sloped section  42  is formed at the end  28  of the holder  12  and includes a sloped inner surface  44 . As can be appreciated, the two sections  34  and the third section  42  define cavities in the inner surface  40  of the side wall  26  which have the sloped surfaces  36  and  44 . The slope of the three sloped inner surfaces is the same. The sloped surfaces  36  are of the same length. The sloped surface  44 , however, is shorter than the surfaces  36 . The side wall  24  also includes a sloped portion  46  opposite the sloped portion  42 . However, the inner surface  48  of the wall  24  is substantially straight. Hence, the sloped portion  46  forms an area of the side wall  24  of increased width. The side wall  24  also includes an opening  50  spaced from the top end  30 .  
         [0020]    A pair of openings  52  are formed in the top wall  20 . The openings extend from the side wall  26  and are aligned with the sloped projections  34 . The openings  20  are shown to be generally semi-circular in shape and to have a length, at the wall  26 , approximately equal to the length of the sloped surfaces  36 . The openings are provided to enable a user to see where the top of the soapstone stick is in the holder, so that the user can gauge how much of the soapstone stick remains. The openings  46  can be omitted; their shape can be changed, or they can be replaced with an elongate slot which extends along the top wall to allow for viewing of a greater length of the soapstone.  
         [0021]    The collet  14  (FIGS. 7 and 8) includes a body  60  which is sized to be received within the hollow housing  12 . An arm  62  extends from the base of the body  60  at one side of the body. The arm is generally rectangular in cross-section, and is sized to be received with in the housing  12 . Preferably, the arm  62  has a height slightly less than the height of the housing between the inner surfaces of the housing top and bottom walls  20  and  22 . The inner surface  65  of the arm  62  is substantial smooth. Preferably, the arm inner surface corresponds in shape to the shape of the soapstone stick. In the embodiment shown, the surface  65  is generally planar, and is designed for use with a rectangular soapstone stick.  
         [0022]    The arm  62  has three spaced apart wedges  64  formed on the outer surface  63  of the arm. The wedges  64  have bases  66 , which are preferable generally perpendicular to the arm outer surface  63 . The last wedge  64  is at the end of the arm  62 . Preferably, the end of the arm is curved, as seen in the figures. Hence, the base of this last wedge is not straight or planar, as is the base of the other two wedges. The wedges are spaced apart to be received in the housing sections  34  and  42 , and the slope of the wedges corresponds substantially to the slope of the section inner surfaces  36  and  44 .  
         [0023]    The base of the body  60  is shown to form a curved surface  68 . A generally S-shaped spring member  70  extends form the curved surface  68 . The end of the spring  70  is defined by a leg  72  which ends in a small finger or hook  74 . When relaxed, as seen in FIG. 8, the spring leg  72  extends beyond the side wall of the collet body  60  a distance approximately equal to the width of the housing side wall  24 . Preferably, the spring member is integrally formed with the collet. However, the spring member  70  can be separate from the collet if desired. This would enable the use of different types of spring elements. The top of the collet body  60  can be provided with flanges  73  to increase the surface area of the collet body, to make the collet body more comfortable to press against.  
         [0024]    The collet, as will be described below, is used to advance the soapstone in the holder  10 . Thus, the collet has an overall length that is greater than the length of the housing  12 . For example, as noted above, the holder has an overall length of about 6″. The housing can have an overall length of about 5.7″, and the collet can have an overall length of about 5.85″ to about 5.9″ such that the collet body  60  extends about 0.15″ to about 0.2″ past the end  30  of the housing  12 .  
         [0025]    To assemble the holder  10 , the collet  14  is inserted into the housing  12 , such that the collet arm  62  extends along the housing wall  26  so that the collet wedges  64  will be received in the housing sections  34  and  42 . The collet spring  70  is sized and shaped, and the housing wall opening  50  is positioned, such that the finger  74  at the end of the spring leg  72  will be received in the opening  50 . The spring  70  thus biases the collet to its extended position, as seen in FIG. 1.  
         [0026]    The collet has a width such that the distance between the collet arm inner surface  65  and the inner surface  48  of the housing wall  24  is slightly greater than the width of a soapstone, so that the soapstone can freely slide in the holder. When the holder is in the extended position, as seen in FIG. 1, the spring  70  biases the collet upwardly to its extended position. In this position, the collet wedges  64  engage the inner surfaces  36  and  44  of the housing sections  34  and  42 . This engagement of the collet wedges with the section inner surfaces urges the collet arm toward the housing wall  24 , and hence, the soapstone will be positively engaged and clamped (or gripped) between the collet arm inner surface and the inner surface  48  of the housing wall  24 . Thus, the soapstone will be frictionally held in place in the housing  12  by the collet  14 .  
         [0027]    To advance the soapstone, the body  60  of the collet is depressed to move the collet arm  62  axially along the housing side wall  26 . The extension of the collet body  60  beyond the housing end  30  is sufficient to push the collet  14  axially until the collet wedge bases  66  engage the shoulders  38  of the housing sections  34 . In this position, the collet wedges will be fully received in the sloped housing sections (as seen in FIG. 2); there will be no positive engagement between the sloped surfaces  34  of the housing sections  34 ; and the collet arm will not be urged transversely across the housing. Thus, the grip of the collet on the soapstone will be released, and the soapstone can slide within the housing under the force of gravity. When the soapstone has advanced (either under the force of gravity, or by being pulled by the user), the collet body is released; the spring  70  will return the collet to its extended position (FIG. 1); and the collet will again grip the soapstone in the housing.  
         [0028]    As the soapstone wears down, the soapstone will be in contact with less and less of the collet arm (although the full length of soapstone within the housing will be in contact with the collet arm). The wedge and the housing section at the end of the collet and housing, respectively, will thus enhance the holding power of the collet on the soapstone, especially when the soapstone is short. Additionally, the thickening of the housing wall at  46  opposite the housing section  42  reinforces the end of the housing. Further, the use of three spaced apart sections and wedges causes the collet to be moved transversely across the housing chamber at multiple locations. This will help enhance the gripping of the soapstone by the collet, even when, for example, the end of the soapstone is between the end projection and the middle projection. Hence, although the holder could be made, for example, with only the housing section  42  at the end of the housing and the wedge at the end of the collet arm, the use of multiple wedges and sections enhances the gripping power of the collet.  
         [0029]    As can be appreciated, the holder relies on a spring biased or reinforced wedging action to grip the soapstone (or other marking material) by urging the collet arm transversely across the holder chamber under the interaction of the collet wedges with the sloped inner surfaces of the housing. To provide the greatest frictional grip of the collet arm on the soapstone, the inner surface  65  of the collet arm  62  and the inner surface  48  of the housing wall opposite the collet arm are shaped to conform generally to the shape of the soapstone. Additionally, the collet arm is sized to have a height approximately the height of the soapstone. Thus, although chamber which is formed by the housing and the collet in which the soapstone is received is generally rectangular in cross-section, the holder could work equally well with, for example, a cylindrical marking material, by giving the arm and the housing opposing wall curved inner surfaces.  
         [0030]    As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. For example, although three wedges and projections are shown on the collet and housing, respectively, more or fewer projections could be provided. Additionally, the length and size of the projections and wedges could be changed depending on the size of the marking material being used. The spring  70  is shown to be integral with the collet body. However, the spring  70  could be an independent part. The spring  70  could be replaced with other spring elements. For example, springs could be placed in the housing sections  34  to extend between the section shoulders  38  and the collet wedge base  66 . Alternatively, the housing and collet body could be configured to receive a leaf spring, or a spring washer, which would bias the collet to its extended position of FIG. 1. The end section  42  and its corresponding collet wedge are formed at the end of the housing and the collet arm respectively. The end projection  42  could be spaced slightly from the end of the housing, so that the section  42  could include a shoulder, as with the sections  36 . The wedge at the end of the collet arm would then be moved accordingly. The housing  12  could be formed to have a width such that the outer surfaces of the housing were smooth. In this case, there would be not projecting sections from the housing side wall  26 , and the sloped surfaces  36  and  44  would be the sloped surfaces of cavities formed in the side wall. These examples are merely illustrative.