Abstract:
A tool and method for measuring, marking and/or scoring drywall sheets. The tool includes a housing having front and rear housing sections forming an internal chamber; a spool rotatably mounted within the chamber; a flexible tape stored on the spool and expandable and retractable from the housing; a brake mechanism mounted on the housing and engageable to maintain the tape in an extended position; a guide mounted on a second end of the tape; and a contact device extending from the housing for marking and/or scoring the surface of the sheet. The guide is placed in abutting contact with an edge of the drywall sheet and the contact device is positioned on the exterior surface thereof. The housing is moved across the exterior surface while the guide remains in abutting contact with the edge, and the contact device marks or scores the surface as the housing is moved thereover.

Description:
BACKGROUND OF THE INVENTION 
     Technical Field 
     This application relates generally to construction tools. More particularly, this invention relates to tools used for installation of drywall. Specifically, this invention relates to drywall tool and method of using the same, where the tool includes an extendable tape having a guide at one end and a contact device that is able to mark or score the exterior surface of the sheet while the tool is moved across the surface and the guide is kept in abutting engagement with the edge of the drywall sheet, so as to maintain a constant distance between the edge and the contact device. 
     Background Information 
     Professional drywall installers use a tape measure and a utility knife to install drywall. They will first measure the required opening and note measurements. Then they will move to the stack of drywall that is leaning substantially vertically against a nearby wall. With the previously noted measurements they will pull the tape out so that the desired number is just exiting the tape measure and push the tape lock. With the tape body in one hand and the utility knife in the other hand, they grab the end of the tape with the utility knife hand and then place the body of the tape measure on the edge of the drywall panel. While holding the knife and tape end in the other hand on the drywall, the installer will move along the entire panel scoring the drywall board. This requires a great deal of skill as the tape measure body is not intended to slide sideways along the edge of a sheet of drywall. Holding the tape end and the utility knife in one hand is tricky, inaccurate and potentially dangerous in that the installer may cut himself with the utility knife. Next, the installer will pull the board a few inches away from the wall and impact the opposite side of the scored region with their hand, foot or knee to break the board at the score line. 
     There is therefore a need in the art for a tool that simplifies the marking and cutting operation. 
     BRIEF SUMMARY OF THE INVENTION 
     The drywall tool in accordance with the present invention saves time and potentially reduces the number of injuries which may occur in the workplace. The drywall tool includes a tape which may be extended outwardly from the tool to measure and mark the required opening. The tool includes a locking mechanism which locks the tape in the extended position so that the drywall sheet may be measured and marked without the installer having to repeatedly read numbers on the tape as they mark and score the sheet of drywall. A knife extending outwardly from the tool is engaged with the drywall when the tape is in the correct position and an end thereof is positioned adjacent the edge of the drywall panel. The installer can then run the knife along the panel while maintaining the end of the tape in abutting contact with the edge of the panel. This allows the installer to easily, accurately and safely score the drywall panel. The drywall tool in accordance with the present invention also includes a marking implement that extends outwardly therefrom and which may be used to mark the drywall panel instead of the knife. 
     A tool and method for measuring, marking and/or scoring drywall sheets is disclosed. The tool includes a housing having front and rear housing sections forming an internal chamber; a spool rotatably mounted within the chamber; a flexible tape stored on the spool and expandable and retractable from the housing; a brake mechanism mounted on the housing and engageable to maintain the tape in an extended position; a guide mounted on a second end of the tape; and a contact device extending from the housing for marking and/or scoring the surface of the sheet. The guide is placed in abutting contact with an edge of the drywall sheet and the contact device is positioned on the exterior surface thereof. The housing is moved across the exterior surface while the guide remains in abutting contact with the edge, and the contact device marks or scores the surface as the housing is moved thereover. 
     The method of using a drywall tool in accordance with the present invention for measuring an opening to be filled with a sheet of drywall and marking or scoring the sheet of drywall to match the opening with said tool includes the steps of: 
     placing a tape guide provided on an end of a flexible tape contained on a spool rotatably mounted within the tool on one edge of the opening; 
     retaining the tape guide against the edge; 
     moving the tool so that a contact device on the tool aligns with an opposite edge of the opening; 
     drawing a length of the flexible tape off the spool as the tool is moved; and 
     engaging a brake mechanism to lock the flexible tape against further movement relative to the spool. 
     The method further comprises the steps of: 
     placing the tape guide in abutting contact with an edge of the sheet of drywall; 
     placing the contact device on the tool against an exterior surface of the sheet of drywall so that the length of the flexible tape extends between the edge of the sheet and the contact device; 
     moving the tool parallel to the edge of the sheet and across the exterior surface; 
     marking or scoring the exterior surface of the sheet with the contact device; and 
     maintaining the tape guide against the edge of the sheet during the marking or scoring operation. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       A preferred embodiment of the invention, illustrated of the best mode in which Applicant contemplates applying the principles, is set forth in the following description and is shown in the drawings and is particularly and distinctly pointed out and set forth in the appended claims. 
         FIG. 1  is a perspective view of a drywall tool in accordance with the present invention, shown in a first position where the tape is fully retracted into the device and the edge of the knife extends outwardly therefrom. 
         FIG. 2  is a perspective view of the drywall tool of  FIG. 1  showing the tape partially extended from the tool and showing the edge of the knife extending outwardly from the tool; 
         FIG. 3  is a left side view of the drywall tool of  FIG. 2 : 
         FIG. 4  is a top view thereof; 
         FIG. 5  is a right side view thereof; 
         FIG. 6  is an exploded right side view thereof; 
         FIG. 7  is a right side view of the drywall tool showing a marking implement selectively engaged therewith; 
         FIG. 8  is a front view of the drywall tool as shown in  FIG. 7 ; 
         FIG. 9  is a cross-sectional front view of the tape dispenser showing the locking mechanism in a disengaged position; 
         FIG. 10  is a cross-sectional front view of the tape dispenser showing the locking mechanism in an engaged position; 
         FIG. 11  is a front elevational view of a vertically-oriented drywall panel and showing the drywall tool in accordance with the present invention engaged therewith; 
         FIG. 12  is a partial enlargement of a front elevational view of the drywall tool engaged with the vertically-oriented drywall panel as shown in  FIG. 10 ; and 
         FIG. 13  is a front elevational view of a horizontally-oriented drywall panel showing the drywall tool in accordance with the present invention engaged therewith and showing a score line on the panel between a first and second position of the drywall tool. 
     
    
    
     Similar numbers refer to similar parts throughout the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-10  there is shown a drywall tool in accordance with the present invention and generally indicated at  10 . Tool  10  comprises a housing  12  having a tape assembly  14  and a knife assembly  16  engaged therewith. 
       FIGS. 1-6  show that housing  12  comprises a front housing section  18  and a rear housing section  20  that are joined together along a joint  22 . Both of front and rear housing sections  18 ,  20  preferably are made from a rigid plastic but they may also be made from any other suitable material such as metal. Front housing section  18  includes a first region  24  and a knife casing  26 . 
     First region  24  preferably is generally square in cross-section shape and knife casing  26  is generally triangular over its length from where it originates in first region  24  to its outermost end. First region  24  has a front end  24   a , a rear end  24   b , and a peripheral wall  24   c  extending between the front and rear ends  24   a ,  24   b . Front end, rear end and peripheral wall  24   a - 24   c  are integrally. Rear end  24   b  includes a lip that is of substantially the same shape as peripheral wall  24   c  but is recessed inwardly relative thereto. Peripheral wall  24   c  includes a rear edge  24   d  disposed proximate the lip. Rear edge  24   d  is configured and positioned to be brought into abutting contact with a portion of rear housing section  20  to form joint  22 . 
     Front housing section  18  defines a first part  28   a  of a chamber  28  defined in housing  12 . The first part  28   a  of chamber  28  is bounded and defined by front end, rear end, and peripheral wall  24   a - 24   c . A first part  30   a  of an axle  30  extends into chamber  28  from an interior surface of front end  24   a . First part  30   a  of axle  30  preferably is disposed generally at right angles to the interior surface of front end  24   a  and projects for a distance beyond rear end  24   b . The purpose of axle  30  will be later described herein. 
     In accordance with a specific feature of the present invention, the knife casing  26  extends outwardly from front end  24   a  of first region  24 . Preferably, knife casing  26  is disposed adjacent one side of the front end  24   a  and is offset relative to the longitudinal axis “Y” ( FIG. 4 ) of display tool  10 . Knife casing  26  is oriented generally at right angles to front end  24   a  of front housing section  18 . Knife casing  26  has a top  26   a , a bottom  26   b , a front  26   c , a first side  26   d  and a second side  26   e . A first aperture  32  is defined in top  26   a  of knife casing  26 . A second aperture  34  ( FIG. 8 ) is defined in a portion of front  26   c  and of bottom  26   b  of knife casing  26 . First and second apertures  32 ,  34  are in communication with a cavity (not shown) defined within knife casing  26 . This cavity preferably is additionally in communication with chamber  28 . 
     Peripheral wall  24   c  of first housing section  18  further defines a first part  36   a  of an aperture  36  situated in a location adjacent to and rearwardly from first side  26   d  of knife casing  26  ( FIG. 9 ). Aperture  36  is in communication with chamber  28  and the purpose thereof will be described later herein. 
     Rear housing section  20  of housing  12  is shown in greater detail in  FIG. 6 . Rear housing section  20  comprises a second region  38  and a handle  40 . Second region  38  is substantially square in cross-sectional shape and is configured to be complementary to first region  24  of front housing section  20 . It will be understood that first and second regions  24 ,  38  may have different cross-sectional shapes, such as both being generally circular, without departing from the scope of the present invention. 
     Second region  38  includes a front end  38   a , a rear end  38   b , and a peripheral wall  38   c . Peripheral wall  38   c  is of a substantially identical shape and size as peripheral wall  24   c  of first region  38 . Front end  38   a , rear end  38   b , and peripheral wall  38   c  of second region  38  bound and define a second part (not shown) of the chamber  28  in housing  12 . Additionally, a second part  30   b  ( FIG. 6 ) of an axle  30  extends forwardly from an interior surface of rear end  38   b  of second region  38  and outwardly beyond first end  38   a  thereof. First and second parts  30   a ,  30   b  of axle  30  are configured and oriented to be disposed adjacent each other when first and second regions  24 ,  38  are engaged and secured together. 
     Second region  38  further includes a pair of flanges  48  ( FIGS. 6 and 9 ) which project forwardly from an interior surface of second region  38  and for a distance beyond front end  38   a  thereof. Flanges  48  are separated from each other by a gap  49  ( FIG. 9 ) and the purpose of flanges  48  will be described later herein. Second region  38  further defines a second portion  36   b  of aperture  36  in a location that is aligned with first portion  36   a  defined in first region  24 . A panel  50  is engaged in aperture  36  in such a way that a slot  52  is formed between a lower edge of panel  50  and portions of peripheral wall  24   c / 38   c . Preferably, panel  50  is manufactured from a clear plastic. 
     When first and second regions  24 ,  38  are engaged with each other the rear end  24   b  of first region  24  is received into the second part of chamber  28  and front end  38   a  of second region  38  abuts the edge  24   d  of first region  24 . As best seen in  FIG. 5 , peripheral wall  38   c  defines a plurality of recesses  42  therein that are oriented substantially at right angles to front end  38   a . A fastener  44  is received through a hole (not shown) in each recess  42  and into an aligned hole (not shown) in a boss  46  which extends rearwardly from the interior surface of front end  24   a  of first region  24 . Fasteners  44  secure first and second regions  24 ,  38  together. 
     As indicated previously, rear housing section  20  also includes a handle  40  that extends outwardly from rear end  38   b  of second region  38 . Handle  40  is ergonomically configured for use in either of a left hand or a right hand of an installer. As shown in  FIG. 3 , handle  40  has an upper surface  40   a , a lower surface  40   b  and an end  40   c . Upper surface  40   a  preferably is provided with a plurality of ridges  54  that extend at right angles to longitudinal axis “Y” ( FIG. 4 ) of housing  12 . Ridges  54  make it easier for the user to grip handle  40  and apply pressure to tool  10  during use thereof. The shape of handle  40  along with ridges  54  aid in ensuring that handle  40  does not rotate within the installer&#39;s hand during use of the device. 
     As indicated previously herein drywall tool  10  further includes knife assembly  16 . Knife assembly  16  includes a blade support  56  that is configured to be received within the cavity of knife casing  26  of front housing section  18 . Preferably, blade support  56  is die cast metal. Blade support  56  is generally V-shaped in order to be received within blade support  56 . Blade support  56  has a top edge  56   a , a bottom edge  56   b , a front end  56   c , a rear end  56   d , a first side  56   e  and a second side  56   f . Blade support  56  is configured to be operatively engaged by a knife lock  58 . Knife lock  58  is a manually operable lever that is used to move blade support  56  within knife casing  26  and to lock the same in a particular orientation relative thereto. Preferably, knife lock  58  is die cast metal. Blade support  56  defines a through-hole  60  configured to receive a fastener  62  for securing blade support  56  to knife lock  58 . Additionally, blade support  56  includes a first flange  64  and a second flange  65 . First flange  64  is contacted by a spring  66  disposed about a post  68  on knife lock  58 . Spring  66  biases knife lock  58  into a locked position. Knife lock  58  further includes a ridged seat  69  that is ergonomically designed to receive the installer&#39;s thumb thereon during operation of drywall tool  10 . 
     Blade support  56  further includes a frame  70  for engaging a knife blade  72  therein. Preferably, frame  70  is comprises of a plurality of L-shaped flanges disposed on one of the first and second sides  56   e ,  56   f  of blade support  56 . These flanges include a first leg that extends perpendicularly outwardly from the one of the sides  56   e ,  56   f  of blade support  56  and a second leg that is disposed substantially parallel to the sides  56   e ,  56   f  so that a small pocket is formed between the side and the second leg. Portions of blade  72  are received in this pocket. 
     As indicated above, knife assembly  16  further includes a plurality of blades  72 . Preferably, blades  72  are two-ended utility-knife type blades but any other suitable blade may be used in drywall tool  10 . Frame  70  is configured to receive an end region  72   a  of one of blades  72  therein and to retain the same adjacent the associated side  56   e ,  56   f  of blade support  56 . Each blade  72  further includes a pair of notches  72   b  therein that are configured to engage flanges  74  on knife lock  58 . Referring to  FIG. 7  it should be noted that handle  40  has a centerline axis “X” as measured between its upper surface  40   a  and lower surface  40   b  and extending from its rear end  40   c  toward where it joins second region  38 . Blade  72 , and most particularly tip  73  of blade  72 , extends for a short distance below bottom  12   a  of housing  12  and is positioned a short distance below that centerline “X” of handle. 
     Knife lock  58  is movable between a locked position and an unlocked position. In the locked position, a portion of the upper wall  58   a  of knife lock  58  is wedged within aperture  32  in knife casing  26  and contacts the underside of top  26   a  of knife casing  26 . This wedging engagement substantially prevents movement of blade support  56  in a direction parallel to longitudinal axis “Y”. When it is desired to move knife lock  58  from a locked position to an unlocked position, the installer places his thumb on a ridged seat  69  of knife lock  58  and depresses knife lock  58  inwardly in the direction of arrow “A” ( FIG. 5 )”. The downward movement of knife lock  58  compresses spring  66  and frees upper wall  58   a  from its contact with the underside of top  26   a  of knife casing  26 . Knife lock  58  pivots about fastener  62  during this movement. Knife lock  58  may then be moved in the direction of arrow “B” while downward pressure is maintained on seat  69 . Knife lock thereby causes blade support  56  to be moved in the direction of arrow “B”, thus causing at least a portion of blade  72  to be moved out of the second aperture in knife casing  26 , bringing the cutting surface  72   c  on blade  72  into a position where it may be used to cut drywall, as will be hereinafter described. If the downward pressure on seat  69  is removed, spring  66  returns to its original position and moves knife lock  58  in a direction opposite to arrow “A”, thereby locking blade support  56  and  72  in that location. 
     In accordance with yet another feature of the present invention, drywall tool  10  further includes a blade storage member  78  which is engaged with second side  26   f  of knife casing  26 . Blade storage member  78  comprises a first and second wall  78   a ,  78   b  which bound and define a compartment  80  between them. First wall  78   a  preferably is fixedly secured to triangular member  26  and second wall  78   b  is hingedly secured to first wall  78   a  and is snap-locked thereto. Compartment  80  is configured to receive a plurality of spare blades  75  therein.  FIG. 1  shows that blade storage member  78  defines a tapered aperture  81  in second walls  78   b  that permits the installer to see whether any spare blades  75  are inside storage member  78 . Second wall  78   b  is flipped downwardly to access spare blades  75  and is flipped upwardly to reclose storage member  78 . When it is necessary to replace blade  72 , knife lock  58  is moved to an unlocked position as previously described and is then moved in the direction of arrow “B” ( FIG. 5 ) to where blade  72  extends outwardly from knife casing  26  to a sufficient degree that it is able to be removed from knife casing  26 . Storage member  78  is opened and one of the plurality of spare blades  75  is removed therefrom and is engaged with blade support  56 . Blade support  56  is then withdrawn back into knife casing  26 . It will be understood that any other suitable method of removing blade  72  from knife casing  26  may also be utilized without departing from the scope of the invention. For instance, front and rear housing sections may be disengaged from each other and blade support may be withdrawn from knife casing  26  and moved into chamber  28 . 
     In accordance with yet another feature of the present invention, tape assembly  14  preferably is comprised of a spool  82  onto which a length of measuring tape  84  is wound. Preferably, both spool  82  and tape are comprised of metal but other suitable materials may be used instead. Spool  82  defines an aperture  86  therein that is complementary in size to receive axle  30  therethrough and spool  82  is configured to rotate about axle  30 . Tape  84  has a first end (not shown) that is fixedly engaged with spool  82  and a second end  84   a  secured to a tape guide  88 . Although not illustrated herein, it will be understood that spool  82  includes a spring mechanism which biases spool  82  in such a manner so as to cause tape  84  to be wound up onto spool  82  when it is not locked in position, as will be hereinafter described. Tape  84  further includes an upper surface  85  ( FIG. 10 ) and a lower surface  87 . As indicated previously, upper surface  87  may be provided with indicia  83  such as numbers or markings as is shown in  FIG. 4 . Tape  84  may, alternatively, be free of any markings and/or numbers, as shown in  FIG. 1 , as markings and/or numbers are not necessary to accomplish the method in which the present invention is used. 
     In accordance with a specific feature of the present invention, spool  82  and tape  84  are positioned within chamber  28  so that tape  84  exits housing  12  through slot  52  beneath panel  50 . It should be noted that slot  52  is positioned so that tape  84  exits housing  12  at substantially 90° relative to the longitudinal axis “Y” ( FIG. 4 ) of drywall tool  10 . As indicated previously, panel  50  is manufactured from a clear plastic and this is so that the installer is able to see indicia  83 , such as numbers or line markings on tape  84 , if they are provided, before those indicia exit housing  12  through slot  52 . Tape  84  is movable relative to housing  12  between an extended and a retracted position, as will be hereinafter described. Tape guide  88  cannot pass through slot  52  and it thereby prevents second end  84   a  of tape from being retracted through slot  52  and into the chamber  28  of housing  12 . Tape guide  88  preferably is also die cast metal and comprises a Y-shaped foot  88   a , an upstanding flange  88   b , and a downwardly extending flange  88   c . Foot  88   a  is fixedly secured to second end  84   a  of tape in such a manner that the straight stem of the Y-shaped foot  88   a  is positioned substantially parallel to the longitudinal axis of the tape  84 . The flanges  88   b ,  88   c  are located beyond the edge of tape. Preferably, foot  88   a  is secured to second end  84   a  of tape  84  by rivets or some other suitable means. Upstanding flange  88   b  is disposed generally at right angles to foot  88   a  and extends for a distance upwardly beyond upper surface  85  of tape  84 . Upstanding flange  88   b  preferably is gently convexly curved relative to housing  12 , as is shown in  FIG. 4 , and includes a plurality of ribs  90  on an interior surface thereof. Ribs  90  are disposed opposite housing  12 . The curvature of flange  88   b  and the ribs  90  provided thereon make it easier for an installer to grasp flange  88   b  by inserting a fingertip between flange  88   b  and housing  12 . 
     Downwardly extending second flange  88   c  is also disposed generally at right angles to foot  88   a  and extends for a distance downwardly below bottom surface  87  of tape  84 . Second flange  88   c  preferably is a large radius member that is configured to abut and travel along an edge of a piece of drywall, as will be described later herein. In particular, second flange  88   c  is configured to be complementary in shape to the radius of curvature of an edge of a drywall sheet, such as edge  104   a  of drywall sheet  104  shown in  FIG. 13 . 
     In accordance with yet another feature of the present invention, drywall tool  10  further includes a manually operable brake mechanism  92  that is mounted externally on housing  12 . Particularly, brake mechanism  92  is configured to move up and down a curved detent  112  between an unlocked and a locked position. Detent  112  comprises a first part  112   a  provided on first region  24  and a second part  112   b  provided on second region  38 . Brake mechanism  92  includes a finger tab  92   a  that is provided with a plurality of ridges  94  thereon. A flange  92   b  extends downwardly from finger tab  92   a  and generally at right angles thereto. A brake plate  92   c  is secured to flange  92   b  by a connector  92   d  and brake plate  92   c  and flange  92   b  are disposed substantially parallel to each other. Brake plate  92   c  terminates in an end  92   e  that is configured to engage upper surface  85  of tape  84  when brake mechanism  92  is engaged and to separate from upper surface  85  when brake mechanism  92  is released. As best shown in  FIGS. 6, 9 and 10 , brake plate  92   c  passes through gap  49  between flanges  48  which extend forwardly from rear housing section  20 . Flanges  48  ensure that brake plate  92   c  is retained at all times in the correct orientation relative to tape  84 . 
     In accordance with yet another specific feature of the present invention, drywall tool  10  further includes a holder  96  for a marking implement ( FIG. 5 ). Holder  96  preferably is manufactured from a flexible material, such as rubber, and is fixedly secured to first housing  18 . In particular, holder  96  is positioned adjacent knife casing  26  and extends outwardly from front end  24   a  of first region  24 . Holder  96  includes an aperture  98  that is configured to grippingly engage a marking implement  100  ( FIG. 7 ) therein. Preferably, aperture  98  is substantially “star-shaped” so that marking implement  100  can be inserted therein and the flaps  99  ( FIG. 5 ) will grippingly engage the side surfaces of marking implement  100 .  FIG. 8  shows that holder  96  is oriented so that when a marking implement  100  is engaged therein, the point  100   a  of marking implement  100  is substantially aligned with knife blade  72 . This ensures that if marking implement  100  is used to mark a sheet of drywall, as will be described hereinafter, the point  100   a  will make a mark in substantially the same location as blade  72  will score or cut the drywall sheet. 
     Drywall tool  10  is used in the following manner. In its initial position, shown in  FIG. 1 , tape  84  is wound onto spool  82  and tape guide  88  is disposed adjacent the exterior surface of peripheral walls  24   c ,  38   c  of first and second regions  24 ,  38 . The installer grasps tool  10  by way of handle  40  and will use their other hand to engage upstanding flange  88   b  of tape guide  88  and move flange  88   b  in the direction of arrow “C” ( FIGS. 4 and 9 ) to extend a length of tape  84  outwardly from housing  12 . Tape  84  is unwound from spool  82  until the desired length of tape  84  extends outwardly beyond peripheral walls  24   c / 38   c . It should be noted that tape  84  may only be unwound from spool  82  when brake mechanism  92  is in the disengaged position shown in  FIG. 9 . 
     Once the desired length of tape  84  has been dispensed from spool  82 , the installer will move brake mechanism  92  to the engaged position by depressing it downwardly in the direction of arrow “D” ( FIG. 10 ). This movement causes flange  92   b  to ride along detent  112  and causes end  92   e  of brake plate  92   c  to come into contact with upper surface  85  of tape  84 . This contact prevents further movement of tape  84  in either the direction of arrow “C” or in the opposite direction to arrow “C”. In other words the length of tape  84  extending outwardly from housing  12  remains constant. Obviously, if it is desired to wind some of the tape  84  back onto spool  82 , i.e., to move tape  84  to a retracted position, then brake mechanism  92  is disengaged and the tape  84  will then automatically rewind onto spool  82  because of the spring mechanism (not shown) associated therewith. Brake mechanism  92  also has to be disengaged to increase the length of tape  84  extending outwardly from housing  12 . Brake mechanism may be disengaged by any suitable means such as by the inclusion of a spring mechanism to return the brake mechanism  92  to its original position. Alternatively, brake mechanism  92  may be moved back to its original position by simply pulling it upwardly. 
     It should be noted from  FIGS. 9 and 10  that brake plate  92   c  has a first region proximate connector  92   d  that curves in a first direction and a second region proximate end  92   e  that curves in an opposite direction. The specific curvature of brake plate  92   a  and the orientation of the flanges  48  relative thereto substantially prevent brake mechanism  92  from accidentally disengaging. It will be understood that other or additional locking mechanisms may be provided on brake mechanism  92  to keep it in the engaged position or in the disengaged position. 
     Drywall tool  10  may now be used for three different types of operations. Firstly, tool  10  may be used to measure a gap  103  between two spaced apart drywall sheets such as sheets  101  and  102  shown in  FIGS. 11 and 12  in order to prepare a panel to fit into that gap  103 . Secondly, drywall tool  10  may be used to make a line on a drywall sheet. Thirdly, drywall tool  10  may be used to score or cut a drywall sheet. 
       FIGS. 11 and 12  show a first drywall sheet  101  and a second drywall sheet  102  separated from each other by gap  103  of an unknown size, where the gap is defined as the space between edges  101   a  and  102   a . In order to measure gap  103  to cut a panel to fill the same, the exterior surface  91  of second flange  88   c  of tape guide  88  is placed adjacent edge  101   a  of first panel  101  and is held in that location. Handle  40  is pulled away from tape guide  88  in the direction opposite to arrow “C” ( FIG. 9 ) to extend a length of tape  84  out of drywall tool  10 . When the correct length of tape  84  is reached, i.e., when knife blade  72  is disposed substantially in alignment with edge  102   a , brake mechanism  92  is engaged. The desired locked length of tape  84  then extends outwardly from housing  12 . The installer can then move the locked drywall tool  10  to a third drywall sheet  104  ( FIG. 13 ) and either mark the appropriate size for the panel on the exterior surface of sheet  104  or, immediately score (i.e., cut) third drywall sheet  104  as will be described hereafter. The installer does not need to know the size of the actual opening as the actual size is locked into the arrangement of the extended tape  84  relative to housing  12 . The installer simply needs to use the locked body/tape arrangement  12 / 84  to mark or score the drywall sheet  104 . 
     In order to do this, and as shown in  FIG. 13 , tape guide  88  is engaged with one of the edges  104   a ,  104   c ,  104   d , and  104   e  of drywall sheet  104 . In this instance, tape guide  88  is engaged with edge  104   a . This engagement is accomplished by placing interior surface  89  of tape guide flange  88   c  in abutting contact with edge  104   a . In a marking operation, a marking implement  100  is inserted into hole  98  in holder  96  so that the point  100   a  thereof is substantially aligned or extends slightly beyond bottom  12   a  of housing  12 . Point  100   a  thereof is also substantially aligned with blade  72  and is positioned slightly forwardly of blade  72  ( FIG. 8 ). Bottom  12   a  of housing  12  is placed in abutting contact with exterior surface  104   b  of drywall sheet  102  and starting proximate a first end of sheet  104 , tool  10  is moved in the direction of arrow “E” while pushing tool  10  firmly against exterior surface  104   b  of drywall sheet  104 . Bottom  12   a  of housing  12  is kept in contact with sheet  104  from proximate the first end  104   c  thereof to proximate the second end  104   d  thereof. As housing  12  moves over exterior surface  104   b , tape guide  88  slides along edge  104   a  while the point  100   a  of marking implement  100  simultaneously contacts the exterior surface  104   b  and draws a line  106  thereon. Later, the installer may utilize a separate utility knife, for example, to score drywall sheet  104  along line  106  and then snap the desired panel  110  so formed from the rest of sheet  104 . 
     Alternatively, the marking implement may be omitted from drywall tool  10  and blade  72  can be extended outwardly from knife casing  26  by moving knife lock  58  to a disengaged position, as previously described. Tape guide  88  is then engaged with edge  104   a  of drywall sheet by positioning interior surface  89  of flange  88   c  in abutting contact with edge  104   a . Bottom  12   a  of housing  12  is placed in abutting contact with exterior surface  104   b  of drywall sheet and handle  40  of housing  12  is rotated slightly upwardly away from exterior surface  104   b , thereby causing tip  73  ( FIG. 5 ) of blade  72  to bite into exterior surface  104   b . Housing  12  is then moved across exterior surface  104   b  from first edge  104   c  to second edge  104   d  in the direction of arrow “E”, keeping bottom  12   a  and blade tip  73  in contact with exterior surface  104   b  and continuously applying substantially even pressure on tool  10  in a direction toward exterior surface  104   b . Tape guide  88  is simultaneously kept in engagement with edge  104   a  of drywall sheet  104  as housing  12  is moved in the direction of arrow “E”. Thus, the distance between edge  104   a  and the score line  106  made by knife blade  72  is kept substantially constant. During this entire operation, the installer will keep his or her thumb in contact with seat  69  of knife lock  58  to keep blade  72  extended from tool  10  and to apply substantially constant pressure on blade tip  73 . At any point during this scoring operation the installer is able lift his thumb off seat  69  and blade lock  58  will engage. Drywall tool  10  may be completely disengaged from drywall sheet  104 . Then, when the installer wishes to resume scoring sheet  104 , he or she simply engages tape guide  88  with edge  104   a  again, disengages knife lock  58  and continues scoring sheet  104 . Since the tape  84  remains locked in position relative to tape guide  88 , no adjustments need to be made to guide  88  and the device can be used to complete score line  106 . Once drywall sheet  104  has been scored for the desired distance, the so-formed panel  110  is detached to separate it from sheet  104  in the known manner, i.e., by snapping the panel  110  and sheet  104  apart. 
     It will, of course, be understood that the measuring, marking and scoring operations may be performed on either of a vertical or a horizontally oriented drywall sheet without departing from the scope of the present invention. 
     In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
     Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.