Abstract:
A portable device for inserting fixing elements into predefined seats in a work piece, the portable device including a drive head; a drive rod extending downward from the drive head; a hollow nose piece slidably fit around a lower end of the drive rod, the nose piece being attached to the head and being movable vertically by a predetermined distance with respect to the head and the drive rod; a magazine mounted on the nose piece at a predetermined angle with respect to a lower face of the nose piece for feeding a first fixing element into a horizontal slot on the lower face the nose piece; and a single-blow drive mechanism providing a force produced by a pressurized fluid to an upper end of the drive rod when the drive mechanism is triggered. The force on the drive rod drives the first fixing element into the predefined seat in the work piece.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This application is a Divisional of co-pending application Ser. No. 11/339,682 filed on Jan. 26, 2006, and for which priority is claimed under 35 U.S.C. §120; the entire contents of which is hereby incorporated by reference.  
         [0003]     The present invention relates to a single-blow pneumatic hand tool for inserting t-nuts, and in particular to a pneumatic hand tool for inserting t-nuts having prongs.  
         [0004]     2. Description of Background Art  
         [0005]     The first commonly available t-nuts were stamped fasteners with a hollow shaft with an internal thread and a flange without prongs. These t-nuts had holes in the flange (usually three) that could accept small nails that would be used to hold the t-nut to the work piece. Later (late 1930&#39;s or early 1940&#39;s) t-nuts were introduced with prongs that were formed from the flange. These t-nuts would be located over the hole in a work piece and driven into the work piece with a hammer.  
         [0006]     In the late 1960s, an “auto-sta” octagonal flange 4-prong t-nut, designed to feed in a track of a machine, and a t-nut machine to drive these t-nuts into the work piece, was developed. Today while a significant percentage of t-nuts are inserted using machinery, a substantial market remains where t-nuts are driven into a work piece by hand using a hammer. Specific areas where t-nuts are inserted with a hammer are:  
         [0007]     Small Volume User: Traditional t-nut machines are generally only cost effective when the volume of t-nuts exceeds 50,000, for example.  
         [0008]     Assembly Line Insertion: Some companies believe it to be more cost effective to insert t-nuts on the line while the frame is being assembled.  
         [0009]     T-nuts in Large Work Pieces: Large work pieces are difficult to handle. In modem furniture production, frames are typically cut from large plywood sheets. When the components are large they can be too big and awkward to manipulate into a t-nut insertion machine.  
         [0010]     Work Pieces with Blind Holes: In some applications t-nuts are inserted in a blind hole, such as when used to mount a leveler on a chair leg.  
         [0011]     More recently, a pneumatically operated hand tool for inserting t-nuts has been introduced. This device has a magazine that accepts t-nuts that are collated into strips with a flexible adhesive tape, and uses a pneumatic stapler body with a reversed action. When the tool is at rest, the driver is fully extended in the down position and the tip of the driver sticks out the bottom of the nose piece. To operate the tool, the tip of the driver is first placed in the hole. Pressing down on the tool then releases the trigger safety. Squeezing the trigger initiates the following sequence: (1) The driver retracts, a t-nut is advanced into the nose of the tool by a feeder mounted on the magazine; and (2) When the trigger is released, the driver descends, driving the t-nut into the work piece.  
         [0012]     While the concept of this pneumatically operated hand tool provides some improvement, the tool disclosed therein requires a careful technique during use to ensure that the t-nut is set into the hole properly. A problem often occurs because the driver is used to locate the hole, and squeezing of the trigger retracts the driver. The recoil of that action often causes the tool to move slightly. As a result, the t-nut is very often driven into the side of the hole, making it very difficult to start a screw in the t-nut. By holding the tool a certain way, it is possible to compensate for the recoil and to drive t-nuts properly, but for many users and environments it has never worked satisfactorily. A further problem with conventional single-blow (single-shot) hand tools is that they typically require a secondary safety to prevent injury. Even with a secondary safety, conventional single-blow hand tools cannot completely eliminate the risk of injury to the operator.  
         [0013]     To address the problem of risk of injury to operators of single-blow hand tools, multi-blow hand tools have been proposed. While multi-blow hand tools may address the problem of injury associated with single-blow hand tools, they are slower to operate than single-blow tools.  
         [0014]     An advantage of the single-blow hand tool is one of speed, particularly in the case where the user of the hand tool is inserting a large number of fasteners. The drive cycle with a single-blow tool is practically instantaneous compared with the 1 to 2 seconds that may be required with the multi-blow hand tool. Also when used continuously in a high volume application, the constant vibration of the multi-blow hand tool compared to the single-blow hand tool would lead to operator preference for the single-blow tool.  
         [0015]     On the other hand, the pneumatic motor on the single-blow tool is larger, more powerful and more complex than that used on the multi-blow tool, and for this reason generally is more costly to manufacture. However, for a high volume user, the additional cost will not likely present an obstacle.  
         [0016]     Thus, a need exists for a hand tool that is both fast and safe. The present invention was developed to address the problems of the conventional art including the problems described above.  
       SUMMARY OF THE INVENTION  
       [0017]     According to one feature consistent with some embodiments of the present invention, a portable device for inserting fixing elements into predefined seats in a work piece is provided. The portable device including a drive head; a drive rod extending downward from the drive head; a hollow nose piece slidably fit around a lower end of the drive rod, the nose piece being attached to the head and being movable vertically by a predetermined distance with respect to the head and the drive rod; a magazine mounted on the nose piece at a predetermined angle with respect to a lower face of the nose piece for feeding a first fixing element into a horizontal slot on the lower face the nose piece; and a single-blow drive mechanism providing a force produced by a pressurized fluid to an upper end of the drive rod. The force on the drive rod drives the first fixing element into the predefined seat in the work piece.  
         [0018]     According to another feature consistent with some embodiments of the present invention, the slot of the nose piece is arranged such that the first fixing element is disposed under a lower face of the drive rod and such that a part of the fixing element in the slot projects below the lower face of the nose piece, the projecting part of the first fixing element for locating one of the predefined seats into which the first fixing element is to be inserted.  
         [0019]     According to still another feature consistent with some embodiments of the present invention a method for determining multiple predefined seat locations in a work piece and inserting fixing elements into the seats is provided. The method includes the steps of automatically transferring a first fixing element into a nose piece of a pneumatic hand tool, a barrel tip of the fixing element extending below a lower face of the nose piece, moving the nose piece over the work piece until the barrel tip of the first fixing element meets a first predefined seat; inserting the first fixing element into the first seat by applying pressure on the nose piece and triggering a pneumatic drive mechanism; automatically transferring a second fixing element from the magazine into the nose piece, a barrel tip of the second fixing element extending below the lower face of the nose piece; moving the nose piece over the work piece until the barrel tip of the second fixing element meets a second predefined seat; inserting the second fixing element into the second seat by applying the pressure on the nose piece and triggering the pneumatic drive mechanism; and repeating the steps above until the multiple predefined seat locations are found and filled with the fixing elements.  
         [0020]     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:  
         [0022]      FIG. 1  is a line drawing of a pneumatic hand tool consistent with some embodiments of the present invention;  
         [0023]      FIG. 2  is a profile view of the pneumatic hand tool showing a finger hook of the magazine follower consistent with some embodiments of the present invention;  
         [0024]      FIG. 3  is an exploded drawing of nose and driver assembly of hand tool of the embodiment;  
         [0025]     FIGS.  4 ( a ) to  4 ( h ) illustrate views of an exemplary individual t-nut and a t-nut strip;  
         [0026]     FIGS.  5 ( a ) to  5 ( c ) illustrate a perspective view, a side view, and a sectional view of the drive rod of the hand tool consistent with some embodiments of the present invention;  
         [0027]     FIGS.  6 ( a ) to  6 ( f ) are additional views of a nose piece consistent with some embodiments of the present invention, and FIGS.  6 ( g ) and  6 ( h ) illustrate one embodiment of a safety actuator;  
         [0028]     FIGS.  7 ( a ) to  7 ( e ) are cut-away views showing an exemplary sequence of locating a hole and inserting a t-nut with a nose piece assembly equipped with a safety actuator consistent with some embodiments of the present invention, and FIGS.  7 ( f ) and  7 ( g ) illustrate an operation of the safety actuator;  
         [0029]     FIGS.  8 ( a ) and  8 ( b ) are 3-d views of the nose piece assembly of an alternative embodiment of the present invention;  
         [0030]     FIGS.  9 ( a ) to  9 ( c ) illustrate the functioning of the L-shaped fingers of the alternative embodiment shown in FIGS.  8 ( a ) and  8 ( b );  
         [0031]     FIGS.  10 ( a ) and  10 ( b ) illustrate an alternative embodiment of a safety actuator;  
         [0032]     FIGS.  11 ( a ) to  11 ( e ) are cutaway views (similar to FIGS.  7 ( a ) to  7 ( e )) showing an exemplary sequence of locating a hole and inserting a t-nut with a nose piece assembly equipped with the alternative embodiment of the safety actuator as shown in FIGS.  10 ( a ) and  10 ( b );  
         [0033]      FIG. 12 ( a ) is a perspective view of an exemplary nose piece extender element, and FIGS.  12 ( b ) and  12 ( c ) are perspective views of the nose piece assembly with the nose piece extender attached thereto consistent with some embodiments of the present invention; and  
         [0034]     FIGS.  13 ( a ) and  13 ( b ) are cutaway views (similar to FIGS.  7 ( c ) and  7 ( d )) showing and exemplary sequence of locating a hole and inserting a t-nut with a long barrel using the nose piece assembly equipped with the lower contact element as shown in FIGS.  12 ( a ) to  12  ( c ). 
     
    
     DETAILED DESCRIPTION  
       [0035]     The pneumatic hand tool for inserting t-nuts consistent with some embodiments of the present invention of the present invention is described with reference to  FIGS. 1-3 .  
         [0036]     As can be seen, the pneumatic hand tool  10  for inserting t-nuts  100  has a nose piece and magazine combination (nose piece  50 , angled magazine  60 ), the combination being slidingly attached to a pneumatic drive head  12  and a butt  13  of the casing  14  of the pneumatic hand tool  10 . The magazine and nose piece combination and pneumatic drive head  12  are described below.  
         [0037]     Magazine holding bracket  16  is slidably mounted on shaft  15  that extends downward from butt end  13  of the handle  11 . Magazine holding bracket  16  is also fastened to the magazine  60  by fasteners  16   s.  Since a front end  60   e  of the magazine  60  is rigidly attached to the nose piece  50  and a rear end of the magazine  60  is attached to bracket  16 , the magazine  60  moves up and down together with movement of the nose piece  50 . The magazine  60  has a slot  60   a  for receiving a strip  150  of collated t-nuts  100  and a spring-loaded follower (not shown) that presses the strip  150  towards the nose piece  50 , advancing one of the t-nuts  100  in the strip  150  into the nose piece  50  after every insertion. In  FIG. 2 , the follower (not shown) includes a finger hook  60   f  that is used to pull the follower back against the force of the magazine spring during the process of loading a strip  150  of multiple t-nuts  100 . When pushed from the magazine  60  into the nose piece  50 , the orientation of the t-nut  100  changes from an angle in the range of 20° to 45° with respect to horizontal. A magnet  50   m  positioned in the front of the nose piece  50  draws the t-nut  100  into a horizontal position in the nose piece  50 .  
         [0038]     The pneumatic drive head  12  of the present invention is a single-blow drive head. On the pneumatic hand tool  10  of the present invention, the drive head  12  may feature a cap  12 c and an ergonomic handle  11  for user convenience and ease of use. The pneumatic hand tool  10  of the present invention uses a long drive rod  20 . As can be seen in  FIG. 3 , the drive rod  20  may have a cross-section that is substantially rectangular in shape. Alternatively, the drive rod  20  may have a circular cross-section or a cross-section of another shape (not shown).  
         [0039]     FIGS.  4 ( a ) to  4 ( h ) provide views of an exemplary individual t-nut  100  and a t-nut strip  150 . FIGS.  4 ( a ) and  4 ( b ) shown perspective views on an individual t-nut  100 . As can be seen, the t-nut  100  includes a barrel  130 , flange  110  and multiple prongs P 1  to P 4 . FIGS.  4 ( c ) to  4 ( h ) show a strip  150  of t-nuts  100  collated and held in place by a strip of tape  100 T. FIGS.  4 ( c ) and  4 ( e ) are side views,  FIG. 4 ( d ) is a plan view,  FIG. 4 ( f ) is an end view, and FIGS.  4 ( g ) and ( h ) are perspective views of the strip  150  of t-nuts  100 . The pneumatic hand tool of the present invention may accommodate t-nuts having various base sizes, for example, a small base: 0.625″×0.700″, a large base: 0.830″×0.885″, or other sizes smaller or greater than these.  
         [0040]     The tape  100 T is formed with adhesive on the side applied to the bottom of the t-nuts  100 . Any commonly known material may be used for the adhesive tape  100 T. Once the t-nuts  100  are collated into a strip  150 , the strip  150  is ready to be inserted into the magazine  60 .  
         [0041]     In the pneumatic hand tool  10 , the magazine/nose piece combination is attached to the drive head  12  in such a way that the magazine  60  and nose piece  50  may slide up and down along an extension tube  30  which is mounted by screws  30   s  on the bottom of the drive head  12 . A mechanism prevents the nose piece/magazine from falling off the extension tube  30 . In some embodiments, the mechanism may include a vertical slot  57  machined into a side of the nose piece  50  through which a screw  50   s  is fastened to the extension tube  30 . The nose piece  50  is able to slide up and down the extension tube  30  only over the length of the slot  57 . One or more springs  40  may be fitted between the nose piece  50  and the drive head  12 , in order to bias the nose piece  50  away from the drive head  12 .  
         [0042]      FIG. 5 ( a ) illustrates a perspective view of an exemplary the drive rod  20  of the pneumatic hand tool  10 . Tip end  20   t  presses against the t-nuts  100  when driving the t-nuts.  FIG. 5 ( b ) is a side view of the drive rod  20  as viewed in the direction of arrows  5 B in  FIG. 5 ( a ), and  FIG. 5 ( c ) is a sectional view of the drive rod as viewed in the direction of arrows  5 C in  FIG. 5 ( b ).  
         [0043]     In order to insert a t-nut  100  in a single blow, the single-blow hand tool has a stroke length of ½″ to 1″, depending on the height of the t-nut, and delivers significantly more power than is typically required in a multi-blow hand tool. The longer stroke and added power, however, increase the risk of injury to the operator of the tool. In order to address this risk, the single-blow hand tool  10  includes a trigger safety mechanism  80  that includes a safety actuator  81  mounted on the nose piece  50 .  
         [0044]     With reference to FIGS.  6 ( a ) to  6 ( h ), one embodiment of the nose piece  50  and safety actuator  81  are describe in further detail. In particular, FIGS.  6 ( a ) to  6 ( d ) include a perspective view, a side view, a bottom view, and a plan view, respectively, of nose piece  50 .  FIG. 6 ( e ) is a sectional view taken along line  6 E- 6 E of  FIG. 6 ( d ), and  FIG. 6 ( f ) is a sectional view taken along line  6 F- 6 F of  FIG. 6 ( d ). Note particularly that when the t-nut  100  is in position in the nose piece  50 , it is constrained by the slot  52  from moving upwardly by a roof  52   f  of the slot  52 , or from moving laterally by side walls  52   a,    52   b,    52   c  of the slot  52 . FIGS.  6 ( a ) to  6 ( f ) also show central bore  53 , opening  53   o  at the bottom of central bore  53 , one or more spring holes  54  for accommodating spring(s)  40 , vertical slot  57 , notch  50   n  for accommodating a front end  60   e  of the magazine  60 , screw hole  55  for accommodating screw  60   s  and rigidly attaching the front end  60   e  of magazine  60  to the nose piece  50 , bottom face  50   f  of the nose piece  50 , recess  50   r  on a side face of the nose piece  50 , and bores  56 ,  56   a,  and  56   b  for insertion of one or more magnets  50   m  into the nose piece  50 .  
         [0045]     FIGS.  6 ( g ) and  6 ( h ) provide a side and a perspective view of one embodiment the safety actuator  81 . As can be seen, safety actuator  81  includes and upper tip  81   t,  an upward extending portion  81   s,  an upper shoulder  81   sh,  and a hole  81   h  for accommodating a fastener  81   f  (See FIGS.  7 ( a ) and  7 ( b )) for mounting the safety actuator in a recess  50   r  on one side of the nose piece  50 .  
         [0046]     Referring to FIGS.  7 ( a ) to  7 ( g ), the pneumatic drive mechanism and safety mechanism of the hand tool  10  will be described. In particular, FIGS.  7 ( a ) to  7 ( e ) show a sequence of using the hand tool  10  for locating a hole  210  in the work piece  200  and inserting a t-nut  100  into the hole  210 .  
         [0047]     In  FIG. 7 ( a ), the hand tool  10  is in a rest position above the work piece  200 , and there is a gap between the bottom end of the drive rod  20  and the flange  110  of the t-nut  100  that is positioned in the nose piece  50 . Of course, prior to using hand tool  10 , the operator loads a strip  150  of t-nuts  100  into the magazine  60  of the hand tool. The spring loaded follower (not shown) pushes on the distal end of the strip  150 , bringing the first t-nut  100  into position in the nose piece  50 . Magnets  50   m  holds the t-nut  100  in place in slot  52  (see FIGS.  6 ( a ) to  6 ( f )). The barrel  130  of this t-nut  100  protrudes downward below the magazine  60  and the barrels of the other t-nuts  100  in the strip  150 . In  FIG. 5 ( a ) tip of the barrel  130  of the t-nut is not yet inserted into the hole  210 .  
         [0048]     To insert a t-nut  100  into a work piece, the operator locates the t-nut  100  in the nose piece  50  into the hole, as shown in  FIG. 7 ( b ), and then presses down on the hand tool body, as shown in  FIG. 7 ( c ). This causes the magazine and nosepiece assembly to slide upward until the upper shoulder  81   sh  of the safety actuator  81  pushes up against a downward facing surface of sleeve  12   s  of the drive head. As upper shoulder  81   sh  of the safety actuator  81  pushes up against a downward facing surface of sleeve  12   s,  gap G shown in FIGS.  7 ( a ) and ( b ) is closed. At the same time, an upper tip  81   t  of the safety actuator  81  pushes upward on a tip  82   t  of an actuator plate  82 . The actuator plate  82  is made of a rigid material and is pivotably mounted at pivot point  82   p.  Sleeve  12   s  acts as a guide channel for the safety actuator  81 , allowing smooth up and down movement, while preventing any lateral movement.  
         [0049]     Next, as can be seen in  FIG. 7 ( d ), when the operator of the hand tool pulls trigger  80 T, an actuator plate  82  pushes upward against the downward force of spring  83  and depresses valve stem  84 , thereby activating a pulse of the drive mechanism, and driving a t-nut  100  into the work piece with a single blow. Note, that as shown in  FIG. 7 ( d ), the upper shoulder  81   sh  of the safety actuator  81  remains pushed up against a downward facing surface of sleeve  12   s  of the drive head as the trigger  80 T is pulled.  
         [0050]      FIG. 7 ( d ) also shows the process of driving the prongs P 1 -P 4  of the t-nut  100  into the work piece  200  breaks the tape  100 T that connects t-nut  100  to the remaining t-nuts in the collated strip.  
         [0051]     When the t-nut  100  has been completely driven into the work piece  200 , the operator lifts the hand tool  10  off the work piece  200 , the spring(s)  40  push the drive head  12  and the nose piece and magazine assembly apart.  FIG. 7 ( e ) illustrates the hand tool  10  having returned to this so-called rest position, as shown in  FIG. 7 ( a ). In the rest position, the nose piece  50  is in the down position, and the upper shoulder  81   sh  of the safety actuator  81  is separated from the downward facing surface of the sleeve  12   s  by gap G. When the nose piece  50  and magazine  60  are extended downward, the follower of the magazine  60  pushes the next t-nut  100  into position in the nose piece  50 , and the hand tool  10  in ready to insert the next t-nut  100  into the next hole.  
         [0052]     Next, with reference to FIGS.  7 ( f ) and  7 ( g ), the operation of the safety mechanism  80  will be described. The safety mechanism  80  allows the drive mechanism to be activated by the trigger  80 T only when nose piece  50  is moved upward by applying downward pressure on hand tool  10 . In particular,  FIG. 7 ( f ) shows pulling of the trigger  80 T while the hand tool  10  is still above the work piece  200 . In this instance, pulling the trigger  80 T causes the trigger to rotate such that the forward tip  82   t  of the actuator plate  82  is no longer above upper tip  81   t.  Thus, the drive mechanism cannot be activated.  
         [0053]     As shown in  FIG. 7 ( g ), hole  210  has been located by the t-nut  100 , and downward pressure has been applied to the hand tool moving nose piece  50  upward. However, since trigger  80 T was pulled prior to applying downward pressure on the hand tool, the upper tip  81   t  of the safety actuator  81  passes by the forward tip  82   t  of the actuator plate  82 . Thus, the actuator plate  82  cannot depress valve stem  84  of the drive mechanism. In other words, in order to activate the drive mechanism, the operator must first apply firm downward pressure on the hand tool  10  to move the nose piece upward so that shoulder  81   sh  of the safety actuator  81  presses up against the downward face of sleeve  12 s. Only then, will the safety mechanism be released, allowing operation of the trigger  80 T to activate the drive mechanism.  
         [0054]     The safety actuator  81  may be integrated with the nose piece  50 , as shown, or may be provided by other means. Further, trigger safety mechanisms  80  other than the sequential style shown may be provided.  
         [0055]     In some applications, foam may be injected around a wood or plastic work piece  200  after the t-nut  100  is inserted. In these cases, it is common for the flange  110  of the t-nut  100  to be covered with a tape in order to prevent foam from reaching the threads inside the t-nut  100 . Since the pneumatic hand tool  10  for inserting t-nuts  100  of the present invention locates the hole  210  in the work piece  200  by actually placing the t-nut  100  in the hole  210 , the need in conventional devices or machines for a separate device to carry the t-nut  100  from the track or magazine to the hole can be eliminated. For this reason, the drive rod  20  of the hand tool  10  of the present invention has only a small locating nib  20   n  (hemispherically-shaped), as opposed to the long guide pin, typically found in conventional devices. If a flexible tape  100 T is used to collate the t-nut strips  150 , the nib  20   n  does not pierce the tape  100 T, leaving it intact on the flange  110  of the t-nut  100 . This can eliminate the need for a secondary taping operation for applications involving injected foam.  
         [0056]     FIGS.  8 ( a ) and  8 ( b ), and FIGS.  9 ( a ) to  9 ( c ), are exemplary illustrations of an alternative embodiment of the present invention. FIGS.  8 ( a ) and  8 ( b ) are 3- d  views of the nose piece assembly of the alternative embodiment from the exterior. Whereas the embodiments described above used one or more magnets  50   m  to retain the t-nuts  100  in the nose piece  50 , this alternative embodiment employs L-shaped fingers  59  attached to the nose piece  50  and extending into slots  59 s so as to retain the t-nut  100  in the nose piece  50 . Alternatively, one or more magnet  50   m  may also be used in conjunction with the L-shaped fingers  59 . The L-shaped fingers  59  in this embodiment may be made of flexible spring strips, such as a flexible steel material, or other flexible material, and may be attached to the nose piece  50  by means of fasteners  58 .  
         [0057]     FIGS.  9 ( a ) to  9 ( c ) illustrate the functioning of the L-shaped fingers  59  showing the cutaway drawings of the nose piece  50  during three successive stages of insertion.  
         [0058]      FIG. 9 ( a ) illustrates the t-nut barrel  130  (slightly inserted into the hole  210 ) prior to insertion of the prongs P 1  -P 4  into the work piece  200 . The L-shaped fingers  59  can be seen retaining the flange  110  of the t-nut  100  in the nose piece  50 .  
         [0059]      FIG. 9 ( b ) illustrates shows the t-nut  100  is being pushed past the L-shaped fingers  59 , the fingers being forced open to allow the flanges  110  of the t-nut  100  to pass.  
         [0060]     In  FIG. 9 ( c ) the insertion of t-nut  100  is complete. The t-nut  100  is fully inserted into the work piece  200 , and the drive rod  20  in a fully extended position.  
         [0061]     Next, referring to FIGS.  10 ( a ) to  10 ( b ), and  11 ( a ) to  11 ( e ), additional features of the invention will be described. These FIGS. illustrate exemplary means for  
         [0062]     (1) adjusting the stoke of the nose piece/magazine assembly, and for  
         [0063]     (2) adapting the tool to accommodate t-nuts having barrels of different lengths.  
         [0064]     FIGS.  10 ( a ) and  10 ( b ) provide two view of an alternative embodiment of a safety actuator  81 ′. Safety actuator  81 ′ differs from safety actuator  81  shown in FIGS.  6 ( g ) and  6 ( h ), in that it is formed with a slot  81   a ′, instead of a hole. Other aspects of safety actuator  81 ′ are the same as safety actuator  81 , so are not repeated here.  
         [0065]     Slot  81   a ′ enables the safety actuator  81 ′ to be mounted at different positions along the side of nose piece  50 . The adjustable safety actuator may be used to control the depth to which the t-nut  100  is driven (for example, if the user would like the upper surface of the flange  110  of the t-nut  100  driven flush with the work piece  200 , or to have the flange  110  remain above the surface of the work piece  200 ), and also to configure the hand tool  10  to work with t-nuts  100  having barrels  130  with different lengths. Common t-nuts have barrel lengths in the range of ¼″ to ⅝″. However, the hand tool  10  of the present invention may be configured to accommodate t-nuts with barrel lengths in the range of 3/16″ to ⅞″, or lengths outside this range.  
         [0066]     FIGS.  11 ( a ) to  11 ( e ) are cutaway views (similar to FIGS.  7 ( a ) to  7 ( e )) showing an exemplary sequence of locating a hole  210  and inserting a t-nut  100  with a hand tool  10  having nose piece assembly equipped with the alternative embodiment of the safety actuator  81 ′, as shown in FIGS.  10 ( a ) and  10 ( b ). Operation of hand tool  10  shown in FIGS.  1   1 ( a ) to  1   1 ( e ) is the same the operation of hand tool  10  shown in FIGS.  7 ( a ) to  7 ( e ), so is not repeated here.  
         [0067]     FIGS.  12 ( a ),  12 ( b ), and  12 ( c ) illustrate still another embodiment of the present invention. In particular,  FIG. 12 ( a ) provides a perspective view of an exemplary nose piece extender  70 , and FIGS.  12 ( b ) and  12 ( c ) are perspective views of the nose piece assembly with the nose piece extender  70  attached thereto. As can be seen, the nose piece extender  70  has a lower portion  70 L which extends under the lower face  50   f  of the nose piece  50 . As such, the nose piece extender  70  extends the length of the nose piece  50 , enabling the nose piece  50  to accommodate t-nuts having barrels  130  of different lengths. The lower portion  70 L of the nose piece extender is formed a slot  72 , the slot  72  having sides walls  72   a,    72   b,  and  72   c.  Slot  72  of the nose piece extender  70  has lateral dimensions substantially equal to those of slot  52  of the nose piece  50 . The lower portion  70 L has a predetermined thickness t, the thickness t being set to accommodate t-nuts  100  having barrels  130  of different lengths.  
         [0068]     FIGS.  13 ( a ) and  13 ( b ) are cutaway views (similar to FIGS.  7 ( c ) and  7 ( d )) showing and exemplary sequence of locating a hole and inserting a t-nut having a longer barrel  130  using the nose piece  50  equipped with the nose piece extender  70 , as shown in FIGS.  12 ( a ) to  12 ( c ).  
         [0069]     As can be seen in  FIG. 13 ( a ), the safety actuator  81 ′ having slot  81   a ′ is positioned on the nose piece  50  so that tip  81 t extends the least amount above the nose piece  50 . This means that in order to activate the hand tool, the operator must depress the hand tool further before the shoulder  81   sh  of the safety actuator  81 ′ contacts the downward facing surface of sleeve  12   s.  In other words, the gap between the nose piece  50  and flange  30   f  is small, since the operator has already depressed to hand tool and is ready to pull the trigger  80 T to drive the t-nut  100  into the hole  210 .  FIG. 13 ( a ) shows the lower face  70   f  of the lower portion  70 L of the nose piece extender  70  being flush with the lowest part of the first t-nut  100  in the magazine  60  (not the t-nut  100  in the nose piece  50 ). When the operator locates the hole  210  in the work piece  200  with the end of the barrel  130  of the t-nut  100  and presses down on the hand tool  10 , the pressure is applied to the nose piece extender  70 , and not the t-nut  100  in the magazine  60 . In  FIG. 13 ( b ), the trigger  80 T is then pulled, and the t-nut  100  is driven into the workpiece  200 .  
         [0070]     Additional alternative embodiments may include one or more of the following features.  
         [0071]     The pneumatic hand tool of the present invention may be adapted to accommodate a wide variety of t-nuts, including t-nuts having different base widths and barrel lengths, and t-nuts with and without prongs. Also, t-nuts with any number of prongs may be accommodated. Further, the front end  60   e  of magazine  60  may be attached to the nose piece  50  by means other than screw  60   s.  In addition, magazines and t-nut feeding devices of various sizes and shapes may be attached to the nose piece  50 . These magazines and t-nut feeding devices may accomodate strips of 15, 20, 50 or 100, or more t-nuts, depending on the base size of the t-nut and the particular magazine or t-nut feeding device used. Still further, while three springs  40  are shown in the nose piece  50 , one, two, or four springs may be used instead.  
         [0072]     Also, while slot  57  and screw  50   s  are used for limiting the up and down movement of the nose piece  50 , other mechanisms may be used. Further, the L-shaped fingers  59  may be used with either of the safety actuators  81  and  81 ′.  
         [0073]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.