Chalk box

A chalk box for producing a chalk line without leakage of chalk dust from within. The chalk box has a chalk-filled chamber that houses a spool and a flexible chalk line. The chalk line extends outwardly around a guidepost and through a fibrous tube. The fibrous tube snugly hugs the flexible line, preventing chalk dust from leaking through the tube. The chalk dust impregnating the flexible line provides lubrication for its passage through the fibrous tube. The present invention also includes a built-in pencil sharpener isolated from the chalk dust, for the convenience of the user.

TECHNICAL FIELD OF THE INVENTION
 The present invention relates generally to the field of measurement tools,
 and more specifically to a device for producing a chalk line on a rough
 surface, such as at a construction site. The chalk box contains a loose
 chalk dust and a retractable line capable of being extended while chalked
 and marking a chalk line when snapped.
 BACKGROUND OF THE INVENTION
 Chalk boxes are well known in the construction field and have long been
 used to mark construction lines. The chalk preferred for use as the
 marking medium is brightly colored and indelible, leaving a readily
 visible and enduring chalk line not easily obscured by the heavy foot
 traffic inherent at a construction site. One persisting problem with known
 chalk boxes is their tendency to leak chalk dust, both when the line is
 extended during use and also during carrying between uses. Chalk dust
 leakage is a problem for several reasons. One such reason is that
 indelible chalk dust produces a brightly colored stain that is difficult
 to remove from clothing and/or other surfaces that are not desired to be
 marked. Finely powdered chalk dust tends to have almost-liquid flow
 characteristics, and thus even if the chalk box is carried in a pocket,
 the leaked chalk dust does not long remain confined. Further, as
 construction technology progresses, increasingly complex and delicate
 electronic tools, equipment, and measurement devices are becoming
 commonplace at the work site. These tools, such as computers, laser
 measurement devices, ultrasonic probes, and the like are all susceptible
 to damage from dust contamination. While care is taken to protect them
 from airborne dust intrusion, accidental direct introduction of chalk dust
 from the clothing or hands of an operator could cause expensive and
 time-consuming equipment damage. Moreover, leaked chalk dust staining the
 work site can obscure or confuse the intentionally laid chalk lines, again
 resulting in the need for repeated measurements and other costly delays,
 decreasing productivity at the work site. Finally, chalk dust leakage
 necessitates more frequent replacement of the chalk dust in the chalk box,
 again decreasing efficiency and productivity.
 Typically, the worker using the chalk box also makes other measurement
 markings at the construction site. Some of these markings involve using
 regular or colored pencils. When these pencils become dull, the worker
 typically uses a knife or utility blade to crudely sharpen them, a process
 that is inefficient and wasteful in that useful pencil is typically shaved
 off along with the wood. Since workers must carry their equipment with
 them, most find it inconvenient to carry a small, loose pencil sharpener
 when they already have a knife. Providing a pencil sharpener that does not
 add to the number of tools the worker must carry would therefore increase
 efficiency and enhance productivity.
 At the work site, productivity is one of the keys to remaining competitive
 and making a profit. Tools that decrease work site delays and increase
 efficiency and productivity therefore help to increase profit. Therefore,
 a need arises for a chalk box that minimizes chalk dust leakage. There is
 a further need for providing a pencil sharpener that does not further
 encumber the worker. The present invention satisfies these needs.
 SUMMARY OF THE INVENTION
 The present invention relates to a chalk box for producing a chalk line
 that decreases the amount of chalk dust leakage common to known chalk
 boxes. In one embodiment, a narrow exit tube is formed through which the
 chalk line exits the chalk box. The tube is surrounded by a fibrous
 material and is formed just wide enough for the line to pass through. The
 passage of the line through the tube is facilitated by the lubrication
 effect of the chalk powder impregnating the line. A built-in pencil
 sharpener is also provided for the convenience of the user.
 One object of the present invention is to provide an improved chalk box.
 Related objects and advantages of the present invention will be apparent
 from the following description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 For the purposes of promoting an understanding of the principles of the
 invention, reference will now be made to the embodiment illustrated in the
 drawings and specific language will be used to describe the same. It will
 nevertheless be understood that no limitation of the scope of the
 invention is thereby intended, such alterations and further modifications
 in the illustrated device, and such further applications of the principles
 of the invention as illustrated therein being contemplated as would
 normally occur to one skilled in the art to which the invention relates.
 FIGS. 1-4 illustrate one preferred embodiment of the present invention, a
 chalk box 10, having a housing 12 having an anterior end 13 and an
 anterior portion 14 and a posterior end 15 and a posterior portion 16. The
 anterior portion 14 further includes an anterior aperture 18 formed
 therein, and the posterior portion 16 includes a posterior aperture 19
 formed therein. The housing 12 may be characterized in greater detail as
 defining a gear chamber 20, a chalk chamber 22, an anterior chamber 24,
 and a posterior chamber 26.
 The gear chamber 20 houses a winding gear 30 and a spool-engaging gear 32.
 Winding gear 30 is fixedly mounted on winding shaft 34. Winding shaft 34
 is rotationally mounted in gear chamber 20 and extends through the housing
 12 to connect to winder 36. Winder 36 is preferably pivotally connected to
 winding shaft 34, such that winder 36 may be pivoted to lie flush with
 housing 12 when not in use and be pivoted upwardly from housing 12 for
 easy gripping when in use. The gear chamber 20 further includes an
 interior cover portion 29 adapted to isolate the gears 30, 32 from the
 remainder of the interior of the chalk box 10, so as to prevent chalk dust
 from contaminating and damaging the gears 30, 32.
 Spool engaging gear 32 is fixedly mounted on spool shaft 38. Spool shaft 38
 is rotationally mounted in chalk chamber 22 with a gear-engaging portion
 40 extending into gear chamber 20. Spool 42 is positioned in chalk chamber
 22 and is fixedly coupled to spool shaft 38. Spool 42 further includes a
 top disc 43 and a bottom disc 44 fixedly mounted to spool shaft 38 and
 spaced apart.
 Chalk chamber 22 is adapted to contain a quantity of chalk dust. Gear
 chamber 20 is adapted to isolate gears 30, 32 from the chalk dust in chalk
 chamber 22. Anterior chamber 24 is in communication with chalk chamber 22
 through a throat 45 defined by their junction, allowing the passage of
 chalk dust back and forth between the chambers 22, 24. Preferentially,
 anterior chamber 24 also contains a guide post 46 positioned near the
 throat 45, although the guidepost 46 could be positioned in the chalk
 chamber 22. Posterior chamber 26 is adapted to contain a pencil sharpener
 48 in isolation from any chalk dust in chalk chamber 22. Anterior chamber
 24 is also adapted to contain a plurality of baffles 52 formed therein
 between the guidepost 46 and the anterior aperture 18. The baffles 52 are
 substantially collinear with the guidepost 46 and the anterior aperture 18
 and are provided to support a line guide tube 54. Guide tube 54 is
 positioned such that it extends substantially collinearly with aperture 18
 and guidepost 46. It is preferred that fibrous wadding or packing 56 at
 least partially fill around baffles 52, supporting tube 54 and providing
 an additional dust seal.
 A flexible line 60 is windingly coupled to spool 42 between top and bottom
 discs 43, 44 such that rotation of spool 42 winds flexible line 48
 therearound. Flexible line 60 extends through chalk chamber 22, through
 throat 45, around guidepost 46 and through tube 54 to pass through
 anterior aperture 18. Flexible line 60 is adapted to easily pick up and
 deposit chalk dust. Tube 54 and the fibrous packing 56 are adapted to
 remove excess chalk dust from flexible line 60 as it passes therethrough,
 substantially preventing loose chalk dust from exiting tube 54 and
 allowing only that chalk dust adhering to flexible line 60 to pass through
 the tube 54. Preferably, tube 54 is sized to snugly hug flexible line 60
 as it passes therethrough. The loose, excess chalk dust removed from
 flexible line 60 as it enters the tube 54 is returned to the chalk chamber
 22, while the quasi-interference fit of flexible line 60 in tube 54
 further discourages chalk dust leakage from chalk box 10.
 Winding gear 30 is meshingly engaged with spool engaging gear 32, such that
 rotation of winding gear 30 actuates rotation of spool-engaging gear 32.
 Likewise, rotation of spool-engaging gear 32 causes rotation of the
 fixedly connected spool shaft 38 and spool 42. Rotation of spool 42 causes
 flexible line 60 to wind around the spool 42, thereby retracting flexible
 line 60 into chalk chamber 22. Spool shaft 38 is adapted to freely rotate,
 such that a worker may easily extend flexible line 60 from housing 12 by
 holding chalk box 10 steady and pulling on flexible line 60. Preferably,
 the gear ratio (the ratio of the number of teeth of one gear to the number
 of teeth of another gear) of the winding gear 30 to the spool-engaging
 gear 32 is substantially large. More preferably, the gear ratio of the
 winding gear 30 to the spool-engaging gear 32 is at least about 4:1.
 Chalk chamber 22 also features a port 70 formed thereinto, through which
 chalk chamber 22 may be filled with and/or emptied of chalk dust. Flexible
 or rigid seal 72 may be employed to plug port 70. Preferably, seal 72 is a
 sliding door, although seal may be of any convenient type for preventing
 undesired communication of chalk dust from chalk box 10.
 Posterior chamber 26 includes a pencil sharpener 48 mounted therein. Pencil
 sharpener 48 is adapted to be accessed by pencils through posterior
 aperture or orifice 19. Posterior aperture 19 is operationally aligned
 with pencil sharpener 48. Posterior aperture 19 is preferably partially
 plugged with cross-slotted flexible plug 76, which is adapted to allow the
 passage of a pencil therethrough while at least partially blocking the
 inadvertent passage of foreign objects thereinto and/or pencil shavings
 therefrom. Posterior chamber 26 further includes a cleanout port 80
 through which accumulated pencil and/or wood shavings may be emptied.
 Cleanout port 80 is plugged by flexible plug 82, adapted to snugly fit
 therein.
 Preferably, chalk box 10 is constructed from an inexpensive, lightweight
 structural material such as plastic (preferred), aluminum, or wood,
 although any convenient material may be chosen. Further, the flexible
 plugs are preferably formed from rubber or flexible plastic, although any
 convenient flexible or pliable material may be selected. Still further,
 the gears are preferably formed from plastic, although any convenient
 structural material may be chosen.
 While the invention has been illustrated and described in detail in the
 drawings and foregoing description, the same is to be considered as
 illustrative and not restrictive in character, it being understood that
 only the preferred embodiments have been shown and described and that all
 changes and modifications that come within the spirit of the invention are
 desired to be protected.