Abstract:
The invention relates to drafting equipment and, more particularly, pertains to a new and improved drafting compass for use with brittle or delicate surfaces. The drafting compass includes an arm rotatable about a bearing axis or axis of rotation. An instrument block is selectively securable along the length of the arm, and the block includes means to selectively secure writing instruments of various sizes.

Description:
[0001]     This application hereby claims the priority benefits of U.S. Provisional Application Ser. No. 60/662,261, which was filed on Mar. 16, 2005. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to drafting equipment and, more particularly, pertains to a new and improved drafting compass for use with brittle or delicate surfaces.  
       BACKGROUND  
       [0003]     Drafting equipment, in general, is a well developed art area that has seen incremental improvements over the years. Each improvement tends to solve specific deficiencies or the specified needs of an industry. For example, drafting equipment improvements have been specifically directed to architects, map makers, teachers, and the like. Improvements have also been made to lessen the cost and complexity of existing drafting tools.  
         [0004]     Many schools, teaching facilities, and researchers make presentations on chalkboards or whiteboards for use in classrooms or labs. When teaching a class, such as a math class, it is common to teach and demonstrate the use of a compass to form various geometric shapes. Compasses historically include a sharp point for a center anchor or bearing point, which would inevitably damage or ruin a chalkboard, whiteboard or the like. Whiteboards can be comprised of many materials but are typically used with dry erase markers or other writing utensils.  
         [0005]     It is also desirable to make a presentation using multiple colors to represent distinct geometric shapes. Multiple colors help illustrate the presenter&#39;s topic and can speed the understanding of the subject that is being conveyed, particularly for a younger audience. Typical drafting compasses do not provide the ability to readily change the writing instrument. A compass may include replaceable writing instruments, but the replacement does not occur quickly enough to satisfy a presenter. Known compasses are also thought to be deficient at accommodating different types and sizes of writing instruments. For instance, it may be necessary to move from a whiteboard to a chalkboard, but a single compass may not be suitable for use with both a whiteboard marker and a piece of chalk. The main problem being that erasable markers used for whiteboards have a relatively large diameter in comparison to most writing instruments. Known drafting compasses cannot accommodate these large size markers and/or cannot accommodate multiple instruments with different dimensions.  
         [0006]     Known compasses also tend to favor a user that is right handed. A compass for a delicate surface is not known to exist that can be easily adapted to a user that is dominant in either their left or right hand.  
         [0007]     Therefore, there exists a need and a challenge to create a drafting compass that is able to be used on a brittle or delicate surface without damaging the board. Ideally, the compass would allow for interchangeable writing instruments, would accommodate writing instruments of various sizes, and would be selectively adjustable to create arcs or circles of different radii. The compass would also be quickly adaptable to user who is left or right handed. The compass would also be inexpensive, easy to operate, and would present a new compass construction assembly. The compass of the present invention solves one or more of these or other needs.  
       SUMMARY OF THE INVENTION  
       [0008]     In accordance with the present invention, a drafting compass is provided that allows for accurate drafting on a brittle or delicate surface material without marking or damaging the surface. The drafting compass of the present invention also includes a means to readily exchange the writing instrument, and the compass accommodates both relatively large and small writing instruments.  
         [0009]     The drafting compass of the present invention, in the broadest terms, includes a soft tipped bearing axis to be placed against a brittle or delicate surface. An arm extends perpendicularly from the bearing axis. An instrument block selectively slides along the arm and retains a writing instrument. The writing instrument is parallel to the axis of rotation/bearing axis and is in contact with the surface to be marked upon. Therefore, rotating the arm around the bearing axis draws an arc or circle with a constant radius.  
         [0010]     In greater detail, the drafting compass of the present invention includes a threaded fastener or shaft, such as a bolt. A soft tip is securely placed over one end of the shaft. An optional washer is placed on the shaft between the soft tip and a rotatable barrel located around the shaft. The arm, which is an elongated member with an axis perpendicular to the axis of the shaft, extends from the barrel. The arm terminates at a first end distal from the barrel. The second end of the arm forms or joins to the barrel. The barrel is dimensioned to accept the shaft, which extends through both ends of the barrel. A knurled nut is placed on the shaft following the barrel. Finally, a knob is threaded onto the shaft until it engages the knurled nut. Each component forming the shaft assembly is in physical contact with the adjacent component(s). The shaft assembly forms the center point or bearing axis that is pressed against a brittle or delicate surface.  
         [0011]     An instrument block is also provided on the arm in a slidable relationship. The block is a machined or molded member with a transverse aperture through the width of the block. The block aperture is dimensioned to slidably fit onto the radius arm via the first end of the radius arm. A marking receptacle in the block is sized to accept markers of various sizes through the height of the block. Markers are, therefore, held in a parallel alignment with the shaft. Fasteners, such as thumb screws, allow the user to selectively secure or release the instrument block relative to both the arm and the writing instrument. The block can be mounted on the arm in a number of positions in order to adapt to a user&#39;s preference or to facilitate use for a right or left handed individual.  
         [0012]     A drafting compass in accordance with the present invention efficiently address at least one of the shortcomings associated with prior art drafting compasses. The foregoing and additional features and advantages of the present invention will become apparent to those of skill in the art from the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective view of a drafting compass in accordance with one embodiment of the present invention;  
         [0014]      FIG. 2  is a front view thereof;  
         [0015]      FIG. 3  is a back view thereof;  
         [0016]      FIG. 4  is a top view thereof;  
         [0017]      FIG. 5  is a bottom view thereof; and  
         [0018]      FIG. 6  is a perspective view of the drafting compass of the present invention wherein the various parts are illustrated in a spaced relationship, the drafting compass being in accordance with one preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0019]     A drafting compass in accordance with the present invention provides an inexpensive, easy to operate, durable, and selectively adjustable instrument. The drafting compass provides accurate geometric shapes, is useable with delicate or brittle writing surfaces, and accommodates writing utensils of various sizes. The compass is adaptable to a left or right handed user.  
         [0020]     Turning to  FIGS. 1-5 , there is illustrated a drafting compass  10  from multiple angles that is in accordance with at least embodiment of the present invention. The compass&#39;s axis of rotation or bearing axis is defined by shaft assembly  12 , which has a first end and a second end. An arm  14  extends from the shaft assembly perpendicular to the axis of the shaft assembly. Arm  14  rotates about the bearing axis. An instrument block  16  is slidable along the length of the arm. Block  16  holds a writing instrument  18 . The instrument, as illustrated, represents a whiteboard marker, but, as will be discussed further below, instruments of various sizes and materials can be easily incorporated. The compass is operable to form geometric shapes with a constant radius.  
         [0021]     In greater detail, the first end of shaft assembly  12  is a soft tip  20 . The tip is a molded polymer, such as rubber, neoprene, or the like, although various materials and construction techniques would be suitable to form the tip. ‘Soft’, for the purposes of this invention, implies that tip  20  acts as a cushion between shaft assembly  12  and a surface to be drawn upon with compass  10 . Therefore, drafting compass  10  is thought to be suitable for use with delicate or brittle surfaces such as chalkboards, whiteboards and the like. Tip  20  is fixed to the assembly in that it does not rotate individually from the other components of the assembly.  
         [0022]     Radius arm  14  is an elongated member extending perpendicularly from shaft assembly  12 . In one preferred embodiment, arm  14  is a metal rod with a square cross section (approximately 3/16× 3/16×14.5 inches). Arm  14  terminates at a first end  22  distal to assembly  12 . A second end  24  is secured to a barrel  26  that is a part of the assembly. The arm is joined to the barrel by known method such as welding, adhesive, or the like. It is also envisioned that arm  14  may be comprised of other materials, such as a machined or molded plastic. The dimensions of the arm can vary based upon consumers desires and the particular application for which the compass will be used. It is also envisioned that the arms of different dimensions might be exchanged onto a single compass.  
         [0023]     In one preferred embodiment, arm  14  and barrel  26  are integral and therefore, consist of a single piece of metal, plastic, or other suitable material. As either a single piece or a plurality of pieces, barrel  26  and arm  14  are independently rotatable about the axis defined by the shaft assembly  12 . A washer  28  is optionally located between barrel  26  and tip  20 . Washer is operable to reduce friction between the tip and the barrel.  
         [0024]     Shaft assembly  12  further comprises a nut  30  adjacent to barrel  26  opposite tip  20 . A knob  32  defines the second end of the assembly. Nut  30 , which is a knurled nut in one preferred embodiment, is positioned between barrel  26  and knob  32 .  
         [0025]     Knob  32  is commonly a molded plastic piece with an upper portion (i.e., the portion furthest from tip  20 ) forming a gripable handle  34  to be engaged by a user. Handle  34  can comprise a smooth or textured shape. Knob  32  further includes a neck portion  36  that tapers the diameter of knob  32  inwards from handle  34  to a vertical column  38  having a reduced diameter. Column  38  is in contact with nut  30 , and typically handle  34  will have a larger diameter than the diameter or width of assembly  12 , in general, and/or nut  30 . The user places a rotating force on knob  32  via handle  34 . Column  38  engages and rotates the nut, which in turn engages and rotates the barrel  26 . The relatively large diameter for handle  34  provides a user with better leverage on compass  10 .  
         [0026]     Block  16  on arm  14  includes an upper surface  40 , a lower surface  42 , left and right sidewalls  44 ,  46 , and front and back ends  48 ,  50 . Although described and illustrated as a rectilinear shape, block  16  can be formed to any number of suitable shapes. A variety of materials, such as plastics/polymers, metals, and the like are suitable. Arm  14  is slidably mounted onto the arm and can be selectively positioned from immediately proximate assembly  12  to any other point along arm  14 .  
         [0027]     In one preferred embodiment, block  16  is placed on arm  14  via a first aperture  52  that passes through block  16  along an axis perpendicular to the axis of shaft assembly  12 . As illustrated, aperture  52  passes through block  16  from left sidewall  44  to right sidewall  46 . Arm  14  is inserted into aperture  52 . Aperture  52  will generally mimic the cross sectional shape of arm  14 , but will exhibit slightly larger dimensions so that block  16  can be readily positioned along the length of the arm.  
         [0028]     A second aperture  54  in block  16  pass through block  16  along an axis parallel to the axis of shaft assembly  12 . As illustrated, aperture  54  passes through block  16  from upper surface  40  to lower surface  42 . Second aperture  54  is sized and dimensioned to accept writing instruments of various sizes. The channels defined by the first and second apertures do not intersect.  
         [0029]     To facilitate the positioning of block  16  relative to arm  14  and the ready exchange or replacement of writing instrument  18 , threaded fasteners are utilized to selectively and individually intersect the axis of the first and second apertures. Specifically, a first fastener  56  passes through block  16  along a path intended to intersect the axis of first aperture  52 . Therefore, fastener  56  engages the arm when the arm has been inserted through the aperture. Fastener  56  acts to secure the block to the arm. The fastener generally has a blunt shank to prevent damage to arm  14 . In one preferred embodiment, fastener  56  is a thumb screw with a blunt shank.  
         [0030]     Likewise, a second threaded fastener  58  facilitates the easy, selective securement and exchange of writing instruments passing through aperture  54 . Second fastener  58  passes through block  16  along a path intended to intersect the axis of second aperture  54 . Where an instrument has been inserted into aperture  54 , fastener  58  physically engages the instrument and holds the instrument between the fastener and the interior of the aperture. Therefore, a user continues to thread the fastener into block  16  until the instrument is frictionally and compressively held between fastener  58  and the interior walls of aperture  54 . Fastener  58  can take many forms but is preferably a thumb screw with a blunt shank.  
         [0031]     The location of both the apertures through the block and the path of the fasteners to intersect the apertures can vary, as would be obvious to one of skill in the art. As illustrated, one preferred embodiment is to mold or machine block  16  to include first aperture  52  proximate to back end  50 . Fastener  56  enters back end  50  perpendicular to the surface of back end  50 . This alignment places the shank of fastener  56  perpendicular to the axis of aperture  52 . The fasteners preferably pass through pre-formed channels that are molded, machined, or otherwise built into the block.  
         [0032]     Second aperture  54  is proximate front end  48 . Fastener  58  can be placed at any angle that would intersect the axis of aperture  54  so long as the path of the fastener does not intersect with aperture  52  or the path of fastener  56 .  
         [0033]     Aperture  54  is illustrated with a square profile to accept writing instruments of various sizes and shapes. In a preferred embodiment, the exterior shape of block  16  includes a mitered corner  60  at the intersection of front end  48  and either sidewall. In this embodiment, fastener  58  enters the front corner of block  16  so that the fastener intersects the axis of aperture  54  along a path aligned from one interior corner of aperture  54  towards an opposing corner. The advantage being that circular instruments  18  are compressed against two of the walls defined by the square-shaped aperture  54 . The angle of the fastener through the aperture facilitates the securement of round instruments  18 .  
         [0034]     Block  16  is easily oriented to a number of positions. For instance, block  16 , once removed from arm  14 , might be rotated about an axis extending from the front end  48  to the back end  50 . The result is that fastener or thumb screw  56  remains on the same side of arm  14 , but sides  44  and  46  are flipped so that fastener or thumb screw  58  extends in a new direction.  
         [0035]     Another optional configuration would be to remove block  16  from arm  14  and rotate the block about an axis extending from side  44  to side  46 . Once returned to the arm, fastener  56  would be on the opposite side of the block. The block could be rotated about two axes. Using this ability, block  16  can easily be reoriented to a position to suit a user&#39;s preferences. For instance, a left handed user would orient the block so that while holding shaft assembly  12  with their right hand, they could easily operate the fasteners  56 ,  58  on the block with their left hand.  
         [0036]     Turning to  FIG. 6 , there is illustrated one preferred embodiment of drafting compass  10  with the various components displayed in a spaced relationship. A threaded shaft  70  with a first end and a second end  72  forms the core of the shaft assembly. Soft tip  20  covers the first end of the shaft. Shaft  70  can be any fastener, such as a bolt, in which case tip  20  is fixed around the head of the fastener. Washer  20  is placed on shaft  70  next to the tip. The washer is followed by barrel  26 , which does not engage the threads on the shaft. Nut  30  is placed on shaft  70  following the barrel. Finally, column  38  of knob  32  includes an interior, threaded diameter that threads onto shaft  70 .  
         [0037]     In use, the user places the shaft assembly against a surface to be drawn upon at a point about which an arc or circle will be illustrated. The shaft assembly is operable as a bearing axis for the illustrated geometric shape. The user grips and rotates knob  32 . Knob  32  transmits the rotational force through nut  30  to barrel  26 . As a result, barrel  26  and arm  14  rotate about shaft  70 .  
         [0038]     The radius or diameter of the resulting arc or circle may be varied by moving the block along the length of the arm. In use, the user rotates thumb screw  56  out of block  16  until fastener  56  no longer engages arm  14 . The arm then slides towards and away from barrel  26  along the length of the arm. Graduation marks or indicators could be used to indicate to the user the size of the resulting arc or circle based on the location of the block on the arm. The user simply threads the fastener into the block when the block as been placed at the desired position on arm  14 .  
         [0039]     Similarly, the user can replace an instrument or exchange one instrument for another type of instrument by simply unscrewing fastener  58  far enough to allow the ingress and egress of the selected instruments with respect to aperture  56 . With the instrument in place, fastener  58  is threaded into the block to secure the instrument.  
         [0040]     While the invention has been described with reference to specific embodiments thereof, it will be understood that numerous variations, modifications and additional embodiments are possible, and all such variations, modifications, and embodiments are to be regarded as being within the spirit and scope of the invention.