Patent Publication Number: US-2022219304-A1

Title: Apparatus for installing fasteners and explosive loads for use therewith

Description:
FIELD OF THE INVENTION 
     This invention relates broadly to explosively driven fasteners More particularly, this invention relates to an apparatus for installing explosively driven fasteners and explosive loads and brackets for use therewith. 
     INCORPORATION BY REFERENCE 
     The disclosure of U.S. Pat. No. 8,397,969 issued Mar. 19, 2013 is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     The fasteners with brackets as disclosed in U.S. Pat. No. 8,397,969 are of unitary construction. However, power charges, nail lengths, and bracket configuration are all individually optimized for a given application. This variability requires a large inventory of the possible power charge/nail/bracket combinations for steady work on a project, causing high inventory costs. Also, in the event of a misfire, bent nail, or excessively spalled penetration, nothing can be salvaged of the power charge/nail/bracket combination, causing waste cost to be undesirably high. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the invention to provide an improved tool for installing an explosively driven fastener that can accommodate nails of different lengths as well as an improved explosively driven fastener for use therewith that permits changeout of bracket configurations and salvage of components in the event of a malfunction. 
     It is a further object of this invention to provide a tool that is safer to unload or clear in the event of a malfunction or failure to fire. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention is in the form of a bracket for attachment to an overhead substrate to carry a suspending wire or rod. The bracket is formed from metal plate or strap stock having a bend connecting a first section of the stock with a second section of the stock. The sections are preferably generally rectangular. The first section of stock defines an aperture, preferably at the bottom of a dimple formed on one side of the stock, preferably by stamping, with a corresponding protuberance, for example, an extrusion, tube or a bulge, preferably a bulge, protruding from the other side. The bulge protrudes alongside the second section of stock. The bulge has a base and an apex, a generally conical outside surface adjacent to the first section of stock and a through aperture at the apex. 
     The bracket will ride on the end of a tool that carries a nail extending loosely through the aperture and has a nest depression to accommodate the protuberance. The tool preferably is adjustable to accommodate different length nails. The bracket is preferably provided with a pre-tied wire. As compared to systems that use brackets that are press fitted to nails, the number of inventory items is greatly reduced. 
     Another embodiment of the invention is provided in the form of a tool for installing an explosively driven fastener. The fastener includes a nail, an explosive load attached to the nail, and a separate bracket. The tool comprises a receiver, a firing pin plunger, a firing pin spring, a firing pin, and a muzzle assembly. The firing pin plunger is located within the receiver. The firing pin plunger has a proximal end and a distal end. The firing spring is arranged to bias the firing pin plunger out of the receiver. The firing pin has a proximal end and a distal end. The distal end is pointed. The firing pin is separate from the firing pin plunger. The proximal end of the firing pin is removably coupled to the distal end of the firing pin plunger. The assembly has a proximal end and a distal end. The proximal end is arranged to receive the firing pin and the distal end is arranged to receive the nail and explosive load, and a portion of the bracket, such that when the fastener is placed on the distal end of the muzzle assembly and the firing pin plunger is biased out of the receiver by the firing spring, the firing pin strikes the explosive load causing the explosive load to explode and drive the nail out of the muzzle assembly. 
     Another embodiment of the invention is provided in the form of a tool having a safety device for installing an explosively driven fastener, the fastener including a nail and an explosive load attached to the nail. The tool comprises a receiver, a firing pin plunger, a firing spring, a firing pin, a muzzle assembly, a trigger plunger and spring, a firing pin guide, and a safety blocking element. The firing pin plunger is located within the receiver. The firing pin plunger has a proximal end and a distal end. The firing spring is arranged to bias the firing pin plunger out of the receiver. The firing pin has a proximal end and a distal end. The distal end is pointed. The firing pin is separate from the firing pin plunger. The proximal end of the firing pin is removably coupled to the distal end of the firing pin plunger. The assembly has a proximal end and a distal end. The proximal end is arranged to receive the firing pin and the distal end is arranged to receive the nail and explosive load, and a portion of the bracket, such that when the fastener is placed on the distal end of the muzzle assembly and the firing pin plunger is biased out of the receiver by the firing spring, the firing pin strikes the explosive load causing the explosive load to explode and drive the nail out of the muzzle assembly. The firing pin guide extends into the receiver, the inner sleeve and the muzzle assembly. The firing pin guide has an outer flange; and the inner sleeve has an inner flange engageable by the outer flange. The trigger plunger and trigger spring are mounted transversely in the firing pin plunger, the trigger being biased radially outward from within the firing pin plunger. The firing pin guide has a slot extending from the proximal end and a widened area in the slot to receive the trigger plunger, and the receiver has an internal trigger shoe receivable by the keyway to depress the trigger plunger by sliding over it. When the tool is in a first resting position, the trigger plunger rests in the widened area of the slot thereby limiting distal movement of the firing pin, and when the tool is in a second firing position, the trigger shoe depresses the trigger plunger out of engagement with the firing pin guide allows distal movement of the firing pin under the action of the firing spring. The receiver has a first end a second end and a sidewall extending between the first end and the second end. The receiver defines a transverse borehole extending though the sidewall. The safety blocking element is mounted for radial movement in the borehole to selectively block the firing pin guide from proximal movement. When engaged, the safety blocking element prevents the firing pin guide from moving sufficiently proximally in the receiver for the trigger plunger to be depressed by the shoe. 
     In another embodiment of the invention, a tool for installing an explosively driven fastener comprises a receiver, a firing pin plunger, a firing spring, a firing pin, a muzzle assembly, and a rubber spall shield carrying a magnet. The fastener includes a nail, an explosive load attached to the nail, and a separate bracket. The bracket can include a depending wire which can be temporarily retained on the side of the tool or its mounting pole by a second magnet. The firing pin plunger is located within the receiver. The firing pin plunger has a proximal end and a distal end. The firing spring is arranged to bias the firing pin plunger out of the receiver. The firing pin has a proximal end and a distal end. The distal end is pointed. The firing pin is separate from the firing pin plunger. The proximal end of the firing pin is removably coupled to the distal end of the firing pin plunger. The muzzle assembly has a proximal end and a distal end, the proximal end is arranged to receive the firing pin and the distal end is arranged to receive the nail and explosive load, and a portion of the bracket, such that when the fastener is placed on the distal end of the muzzle assembly and the firing pin plunger is biased out of the receiver by the firing spring, the firing pin strikes the explosive load causing the explosive load to explode and drive the nail out of the muzzle assembly. The rubbery spall shield surrounds the distal end of the muzzle assembly and has a distal end approximately coplanar with the distal end of the muzzle assembly. The rubbery spall shield carries a magnet for magnetically attaching to a portion of the bracket to locate the bracket until the firing pin strikes the explosive load. 
     Another embodiment of the invention is in the form of a bracket carrying a plastic bushing sized on its outside to closely fit an aperture in the bracket and on its inside to closely fit over a nail carried in a nail gun. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal cross section of a tool in a first, relaxed configuration according to an embodiment of the invention. 
         FIG. 2  is a longitudinal cross section of the tool of  FIG. 1  in a second, cocked configuration and carrying a nail and charge. 
         FIG. 3  is a longitudinal cross section of the tool of  FIG. 2  in a third, triggered configuration. 
         FIG. 4  is a longitudinal cross section of the tool of  FIG. 2  in a fourth, firing configuration. 
         FIG. 5  is a longitudinal cross section of the tool of  FIG. 2  in a fifth, safe configuration. 
         FIG. 6  is a longitudinal cross section of the tool of  FIG. 2  is a sixth, unload configuration. 
         FIG. 7  is a perspective view of an end of a tool according to an embodiment of the invention showing placement of a nail and charge. 
         FIG. 8  is a perspective view of the end of the tool as in  FIG. 7  after placement of the nail and charge. 
         FIG. 9  is a perspective view of the end of the tool as in  FIG. 8  showing placement of a bracket on the nail and end of the tool. 
         FIG. 10  is a longitudinal cross section of an end of a tool according to another embodiment of the invention illustrating placement of a nail and charge. 
         FIG. 11  shows fasteners according to embodiments of the invention. 
         FIG. 12  shows nail/charge combinations according to embodiments of the invention, 
         FIG. 13  shows washer/spacers according to an embodiment of the invention. 
         FIG. 14  shows a nail/charge/bracket combination according to an embodiment of the invention, in cross section. 
         FIG. 15  shows an exploded view of a tool according to an embodiment of the invention, in longitudinal cross section. 
         FIG. 16  is a perspective view of the end of the tool in one embodiment of the invention showing placement of a magnet in the spall shield of the tool. 
         FIG. 17  is a sectional view of the end of the tool as shown in  FIG. 16  when carrying a nail/charge/bracket in accordance with an embodiment of the invention. 
         FIG. 18  is a cross sectional view of a bushing showing certain features of another embodiment of the invention. 
         FIG. 19  is a cross sectional view of a bracket which can be used with the bushing of  FIG. 18 . 
         FIG. 20  is a cross sectional view of a gun assembly as in earlier described embodiment with which the newly described embodiment can be used. 
         FIG. 21  is a cross sectional view of a bushing/bracket combination ready for insertion into the gun assembly of  FIG. 20 . 
         FIG. 22  is a cross sectional view of the bushing/bracket combination of  FIG. 21  after insertion into the gun assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 11 , one embodiment of the invention is in the form of a bracket, for example, one of brackets  2 ,  2 ′,  2 ″ for attachment to an overhead substrate to carry a suspending wire or rod. The bracket is formed from metal plate or strap stock having a bend  4 , preferably a right-angle bend, connecting a first section  6  of the stock with a second section  8  of the stock. The sections are preferably generally rectangular. The first generally rectangular section of stock has a perforation, for example, at the bottom of a dimple  10  formed on one side of the stock, preferably by stamping, with a corresponding protuberance  12  protruding from the other side, for example, an extrusion, bulge or tubing, preferably a bulge. The bulge or other protuberance protrudes alongside the second generally rectangular section of stock. The bulge has a base  14  and an apex  16 , a generally conical outside surface adjacent to the first generally rectangular section of stock and a through aperture  18  at the apex. The inside surface of the bulge is also generally conical. In one preferred embodiment, the bracket  2  further comprises a third section  21  of stock, preferably a rectangular section, connected to the second generally rectangular section of stock by a generally right-angle bend and extending therefrom in a plane generally parallel to the first generally rectangular section of stock in a direction away from the bulge. The third section of stock defines an aperture  22 . In another embodiment, the second generally section of stock of the bracket  2 ″ defines a second aperture  20 . In another embodiment, the second aperture  24  of the bracket  2 ′ is threaded to accept a threaded rod, not shown. 
     In a preferred embodiment, the generally conical outside surface of the bulge converges in the direction of the apex of the bulge at a half-angle in the range of about 30 to about 60 degrees. The bulge has a height that is 30 to 50% of its outside diameter at the base. The stock is steel, the first rectangular section has a length in the range of about 1 to about 4 cm, a width in the range of about 1 to about 4 cm, a thickness in the range of about 0.1 to about 0.3 cm, and the bulge has an outside diameter at the base in the range of about 0.5 to about 1 cm. 
     The brackets of the invention are used in conjunction with a nail  30 . See  FIGS. 10 and 14 . Different length nails  30 ′,  30 ″ for example can be used for different application. See  FIG. 12 . The nail has a cylindrical shaft  31  (See  FIG. 7 ), a longitudinal axis, a pointed distal end  32  and a proximal nail head  34 . The cylindrical shaft is positioned loosely and slidably in the through-aperture of the apex (see  FIG. 14 ) with the pointed distal end protruding in the range of about 0.1 to about 0.5 cm above a surface  7  of the first generally rectangular surface opposite to the protuberance. See  FIG. 9 . 
     With reference to  FIG. 7  for example, the nail is preferably used in combination with a plastic cap  35  having a distal end, a proximal end, and a longitudinal axis. The distal end surrounds the nail head. The proximal end contains a nitrocellulose load  36 . Different strength loads can be provided if needed. The plastic cap is generally cylindrical in shape and has its longitudinal axis positioned coaxially with the longitudinal axis of the nail shaft. The plastic cap preferably has an outside diameter slightly smaller than the outside diameter of the bulge or other protuberance at its base  14 . The cap, nitrocellulose load, and nail are manufactured as a unit. 
     The nail generally has a length between the distal end and the proximal end that is in the range of 2 to 5 cm and the plastic cap and/or nitrocellulose load is preferably color-coded dependent on the length of the nail. 
     Conventional fasteners are comprised of nails and brackets hooks or clips that are mostly assembled using a press-tight fitting or through additional metal fittings that need to be combined before use. The disadvantage of this design is that when the assembled, complete fastener fails to fix to the substrate or the nail fails to shoot, the entire fastener assembly is scrapped and cannot be reused, resulting in excess waste. This invention can reuse the same bracket and, providing that the nail/cap/load piece is replaced, reduces waste. 
     As compared to using a tight-fitting bracket, the bracket only loosely covers the nail piece in the invention, and the tool is adjusted with a color-coded washer  44 ,  44 ′,  44 ″ for example so that the point of the nail piece protrudes above the bracket no more than 5 millimeters. A bowl-shaped structure is provided on the underside of the bracket which enters completely into the tool beneath the bracket beneath the nail tip. This bowl structure enters completely into the tube of the tool cover, preventing nails from sliding when applying the bracket to the substrate. The feature assures that the nail is driven in straight. 
     To determine the shortest usable nail length, load the nail into the nosepiece of the tool until the head of the nail starts to touch the firing pin guide inside of the tool, then loosely encase the nail with the hook/clip bracket piece. When the point of the nail protrudes no more than 5 millimeters the shortest length of nail that can be used has been determined. The solution to the issue of coupling different lengths of nails is in utilizing different thicknesses of spacers to adjust the nail protrusion. The different lengths of spacers allow different lengths of nails to be loaded into the tube and ensure that after equipping the bracket the nail does not protrude more than within a 5-millimeter range outside the barrel of the nosepiece. 
     The combination is preferably used in conjunction with a muzzle assembly  40 , (See  FIG. 10 ) a color coded washer  44 ,  44 ′,  44 ″, an inner sleeve  46 , and a receiver  48  (see  FIG. 1 ). The inner sleeve has a distal annular endface and a proximal end. The muzzle assembly defines a generally cylindrical throughbore  50  and having a distal end and a proximal end and the distal end defines an annular endface  42 . The distal end of the muzzle assembly closely receives the proximal end of the plastic cap in the throughbore. The proximal end of the muzzle assembly is threaded to the inner sleeve. The color-coded washer is retained between annular endfaces on the muzzle assembly and the inner sleeve. The inner sleeve is slidably carried by the receiver. 
     The distal annular endface of the muzzle assembly contacts the first section of stock. See  FIG. 9 . A rubbery spall shield  52  is preferably carried on the muzzle assembly and has a segment cutaway  54  to accommodate the bracket. The cutaway has the added benefit of preventing the bracket from spinning around during manipulation of the tool. The spall shield has a distal annular endface that surrounds and is approximately co-planar with the distal annular endface of the muzzle assembly. A magnet  55  is preferably mounted in a recess, for example, a borehole, in the distal annular endface of the spall shield. The magnet is preferably located between the distal annuar endface of the muzzle assembly and the cutaway. See  FIG. 16 . The magnet can be cylindrically shaped and can be secured by adhesive. The magnet preferably has a flat distal face that is approximately co-planar with the distal annular endface of the spall shield. The magnet helps locate the bracket after it has been placed. See  FIG. 17 . The tool further comprises a firing pin guide  56  having a distal end and a proximal end slidably mounted in the generally cylindrical throughbore of the muzzle assembly. The distal end of the firing pin guide supports the proximal end of the plastic cap so that the pointed distal end of the nail protrudes in the range of about 0.1 to about 0.5 cm above a surface of the first generally rectangular surface of the bracket opposite the protruding bulge. The color coded washer has a thickness as measured longitudinally which is related to the color code of the plastic cap and/or nitrocellulose load to space the distal end of the muzzle assembly from the distal end of the inner sleeve adequately to cause the distal end of the nail to protrude above the surface of the bracket in the range of 0.1 to 0.5 cm when the colors match. 
     The generally cylindrical throughbore of the muzzle assembly preferably has an inside diameter that is slightly larger than an outside diameter of the plastic cap. The throughbore preferably has a chamfer where it opens onto the distal endface of the muzzle assembly to provide a nest for the bulge. By accommodating the bulge, a proximal surface of the bracket can lie flat against the distal end surface of the muzzle assembly so that the bracket is stably positioned on the end of the tool. 
     In a preferred embodiment, the firing pin guide has an annular outwardly extending proximally facing flange  58  between the distal end and the proximal end and the inner sleeve has an annular inwardly extending distally facing flange  60  between the distal end and the proximal end for abutting the annular outwardly extending proximally facing flange of the firing pin guide. See  FIG. 6 . This causes the firing pin guide and the inner sleeve to move proximally together when the firing pin guide is urged proximally. 
     The receiver has a first end  62  a second end  64  and a sidewall extending between the first end and the second end. The receiver defines a transverse borehole  66  extending though the sidewall. A safety blocking element  68  is mounted for radial movement in the borehole to selectively block the firing pin guide from proximal movement. Compare  FIGS. 1 and 5 . The receiver further carries a trigger shoe  70  extending radially inwardly from the sidewall of the receiver at a location between the safety blocking element and the proximal end of the receiver. 
     A firing pin  72  is mounted in the firing pin guide. A firing pin plunger  74  is mounted to the firing pin and extends longitudinally proximally therefrom. A trigger plunger  76  is mounted in a transverse passage in firing pin plunger and is biased radially outwardly to move proximally with the firing pin guide until depressed by the trigger shoe. The safety blocking element when engaged prevents the firing pin guide from moving sufficiently proximally for the trigger plunger to be depressed by the shoe. 
     In a preferred embodiment, an outer sleeve  78  is mounted on the receiver. The outer sleeve has a longitudinal axis, a longitudinally extending inner slot  80 , and an outwardly protruding portion  82  defining a radially outwardly extending ridge over the slot. See  FIG. 6 . The radially extending ridge defining a transverse borehole and a cam  84  is mounted in the borehole and extends across the slot. An arm  86  is mounted on one end of the cam to permit about a 90-degree rotation of the cam. The outer sleeve is mounted on the receiver so that the cam depresses the safety blocking element and prevents the firing pin guide from moving sufficiently proximally for the trigger plunger to be depressed when actuated. 
     The distal end of the firing pin guide is near the distal end of the barrel when the firing pin guide contacts the safety blocking element to permit ejection of the plastic cap from the generally cylindrical throughbore of the muzzle assembly by moving the inner sleeve proximally. See  FIG. 6 . The blocking element preferably comprises a ball bearing, as illustrated. 
     Another embodiment of the invention is provided in the form of a tool  100  for installing an explosively driven fastener. The fastener includes a nail, an explosive load attached to the nail, and a separate bracket. The tool comprises a receiver  48 , a firing pin plunger  74 , a firing spring  75 , a firing pin  72 , and a muzzle assembly  40 . The firing pin plunger is located within the receiver. The firing pin plunger has a proximal end and a distal end. The firing spring is arranged to bias the firing pin plunger out of the receiver. The firing pin has a proximal end and a distal end. The distal end is pointed. The firing pin is separate from the firing pin plunger. The proximal end of the firing pin is removably coupled to the distal end of the firing pin plunger. The muzzle assembly has a proximal end and a distal end. The proximal end is arranged to receive the firing pin and the distal end is arranged to receive the nail and explosive load, and a portion of the bracket, such that when the fastener is placed on the distal end of the muzzle assembly and the firing pin plunger is biased out of the receiver by the firing spring, the firing pin strikes the explosive load causing the explosive load to explode and drive the nail  30  out of the muzzle assembly. 
     Preferably, the tool further comprises an inner sleeve  46  coaxially mounted within the receiver. The inner sleeve has a proximal end and a distal end. An inner sleeve spring  47  biases the inner sleeve away from the receiver. An annular spacer  44  is positioned between the distal end of the annular sleeve and the proximal end of the muzzle assembly. The fastener includes the nail  32 , an explosive load  36  attached to the nail, and a separate bracket  2  loosely penetrated by the nail. The distal end of the muzzle assembly is chamfered to nest a portion of the bracket which is bulged out frustoconically. If desired, a second annular spacer having a different thickness longitudinally than the annular spacer can be provided to change a distance that the distal end of the nail protrudes from the distal end of the muzzle assembly or provide for the use of different length nails. Generally speaking, the spacer has an adequate thickness to cause the distal end of the nail to protrude in the range of 0.1 to 0.5 cm above the distal end of the muzzle assembly. Preferably, a distal end of the muzzle assembly supports most of a flat portion of the bracket around the bulge. More preferably, the distal end of the muzzle assembly supports most all of a flat portion of the bracket around the bulge. See  FIG. 9 . 
     This invention also adds a series of spacers with different thicknesses based on the existing tool, which is used to adjust the tool to allow the use of different lengths of pins. The invention allows the user to be able to match all different kinds of hooks &amp; clip devices depending on application, greatly increasing its versatility, thus reducing product SKU&#39;s and lowering inventory cost. 
     In a preferred embodiment, the tool comprises a firing pin guide  56  extending into the receiver, the inner sleeve and the muzzle assembly. The firing pin guide has an outer flange  58  and the inner sleeve has an inner flange  60  engageable by the outer flange. A trigger plunger  76  and a trigger spring  77  mounted transversely in the firing pin plunger, the trigger being biased radially outward from within the firing pin plunger. The firing pin guide has a slot  57  extending from the proximal end and a widened area  59  in the slot to receive the trigger plunger. The receiver has an internal trigger shoe  70  receivable by the keyway to depress the trigger plunger by sliding over it. When the tool is in a first resting position, ( FIG. 1 ) the trigger plunger rests in the widened area of the slot thereby limiting distal movement of the firing pin. When the tool is in a second firing position ( FIG. 3 ), the trigger shoe depresses the trigger plunger out of engagement with the firing pin guide and allows distal movement of the firing pin under the action of the firing spring. 
     In a preferred embodiment, the receiver has a first end a second end and a sidewall extending between the first end and the second end. The receiver defines a transverse borehole  66  extending though the sidewall. The tool further comprises a safety blocking element  68  mounted for radial movement in the borehole to selectively block the firing pin guide from proximal movement. The safety blocking element when engaged prevents the firing pin guide from moving sufficiently proximally for the trigger plunger to be depressed by the shoe. 
     More preferably, an outer sleeve  78  is mounted on the receiver. The outer sleeve has a longitudinal axis, a longitudinally extending inner slot, and an outwardly protruding portion  82  defining a radially outwardly protruding, longitudinally extending ridge over the slot. The ridge defines a transverse borehole. A cam  84  is mounted in the borehole and extends across the slot. An arm  86  on one end of the cam permits about a 90-degree rotation of the cam. The outer sleeve is positioned on the receiver so that the cam depresses the safety blocking element and prevents the firing pin guide from moving sufficiently proximally for the trigger plunger to be depressed. 
     Another embodiment of the invention is provided in the form of a tool  100  having a safety device for installing an explosively driven fastener, the fastener including a nail and an explosive load attached to the nail. The tool comprises a receiver  48 , a firing pin plunger  74 , a firing spring  75 , a firing pin  72 , a muzzle assembly  40 , a trigger plunger  76  and spring  77 , a firing pin guide, and a safety blocking element. The firing pin plunger is located within the receiver. The firing pin plunger has a proximal end and a distal end. The firing spring is arranged to bias the firing pin plunger out of the receiver. The firing pin has a proximal end and a distal end. The distal end is pointed. The firing pin is separate from the firing pin plunger. The proximal end of the firing pin is removably coupled to the distal end of the firing pin plunger. The assembly has a proximal end and a distal end. The proximal end is arranged to receive the firing pin and the distal end is arranged to receive the nail and explosive load, and a portion of the bracket, such that when the fastener is placed on the distal end of the muzzle assembly and the firing pin plunger is biased out of the receiver by the firing spring, the firing pin strikes the explosive load causing the explosive load to explode and drive the nail  30  out of the muzzle assembly. The firing pin guide extends into the receiver, the inner sleeve  46  and the muzzle assembly. The firing pin guide has an outer flange  58  and the inner sleeve has an inner flange  60  engageable by the outer flange. The trigger plunger  76  and trigger spring  77  are mounted transversely in the firing pin plunger, the trigger being biased radially outward from within the firing pin plunger. The firing pin guide has a slot  57  extending from the proximal end and a widened area  59  in the slot to receive the trigger plunger, and the receiver has an internal trigger shoe  70  receivable by the keyway to depress the trigger plunger by sliding over it. When the tool is in a first resting position, the trigger plunger rests in the widened area of the slot thereby limiting distal movement of the firing pin, and when the tool is in a second firing position, the trigger shoe depresses the trigger plunger out of engagement with the firing pin guide allows distal movement of the firing pin under the action of the firing spring. 
     The receiver has a first end a second end and a sidewall extending between the first end and the second end. The receiver defines a transverse borehole  66  extending though the sidewall. The safety blocking element  68  is mounted for radial movement in the borehole to selectively block the firing pin guide from proximal movement. When engaged, the safety blocking element prevents the firing pin guide from moving sufficiently proximally in the receiver for the trigger plunger to be depressed by the shoe. 
     More preferably, an outer sleeve  78  mounted on the receiver. The outer sleeve has a longitudinal axis, a longitudinally extending inner slot, and an outwardly protruding portion defining a radially outwardly protruding, longitudinally extending ridge over the slot. The ridge defines a transverse borehole. A cam  84  is mounted in the borehole and extends across the slot. An arm  86  on one end of the cam permit about a 90-degree rotation of the cam. The outer sleeve is mounted on the receiver so that the cam blocks radially outward movement of the safety blocking element and prevents the firing pin guide from moving sufficiently proximally for the trigger plunger to be depressed when it is actuated. Preferably, the safety blocking element comprises a ball bearing. 
     One embodiment of the invention is to provide a safety device that prevents the firing function of the tool when the safety is properly engaged. Besides conforming to the traditional requirements of fastening tools that require the user apply a specific amount of compression force to actuate the tool upon contact with the substrate, this device has an added safety catch to disable the device from firing when not in use. Actuating the safety while servicing the tool or dislodging jammed fasteners helps avoid accidents and ensure increased safety. A round steel bearing is installed in the receiver. The bearing is longitudinally spaced in front of the trigger. When used to apply fasteners, the bearing is able to move up and down radially without influencing actuation by trigger. The safety mechanism, when engaged, puts a pressure release on the head of the steel bearing which stops the bearing from moving up and down radially and prevents the radial movement of the trigger plunger, thus inhibiting the mechanism&#39;s ability to fire. 
     Another embodiment of the invention, with reference to  FIGS. 18-22 , comprises a bracket  2 ′ for attachment to an overhead substrate to carry a suspending wire or rod. The bracket is formed from metal plate or strap stock having a bend  194 , preferably a right-angle bend, connecting a first section  196  of the stock with a second section  198  of the stock. The sections are preferably generally rectangular. The first generally rectangular section of stock has a perforation  197 , for example, at the bottom of a dimple  1910  formed on one side of the stock, preferably by stamping, with a corresponding protuberance  1912  protruding from the other side, for example, an extrusion, bulge or tubing, preferably a bulge. The bulge or other protuberance protrudes alongside the second generally rectangular section of stock. The bulge has a base  1914  and an apex  1916 , a generally conical outside surface adjacent to the first generally rectangular section of stock and a through aperture  1918  at the apex. The inside surface of the bulge is also generally conical, in the illustrated embodiment, frustoconical where it opens onto the upper surface of the bracket, and generally cylindrical at the aperture  1918 . The aperture is of larger diameter than the aperture of earlier embodiments to accommodate a plastic bushing  1920  extending through the through-aperture. See  FIG. 21 . The bushing is preferably constructed of a thermoplastic material, for example, Nylon®. The bushing has a first end and a second end. An annular flange  1922  extends radially outwardly at its first end. A through-passage  1924  extends from the first end to the second end. The annular flange at the first end of the plastic aperture is received by the dimple on the upper surface of the bracket. The plastic bushing has a generally cylindrical or slightly tapered outer surface that is closely received by the through-aperture opening at the apex of the protuberance. In the illustrated embodiment, the bushing has at least one fin or barb  1926  protruding from its generally cylindrical outer surface contacting the apex of the protuberance to retain the annular flange in the dimple. 
     The bracket/bushing combination is used in combination with a nail  30 , cap  35  and load  36 , and gun muzzle assembly  40 . The nail has a cylindrical shaft, a longitudinal axis, a pointed distal end  32  and a proximal nail head  34 . The cylindrical shaft is positioned snugly in the through-passage of the bushing, and this is different from the embodiments described earlier herein. The pointed distal end of the nail protrudes in the range of about 0.1 to about 0.5 cm above a surface of the first section of stock opposite to the protuberance. The plastic cap has a distal end, a proximal end, and a longitudinal axis. The distal end surrounds the nail head and the proximal end contains the nitrocellulose load. The plastic cap is generally cylindrical in shape and has a longitudinal axis positioned coaxially with the longitudinal axis of the nail shaft. The plastic cap has an outside diameter slightly smaller than the outside diameter of the protuberance at the base. The muzzle assembly defines a generally cylindrical throughbore  50  and has a distal end and a proximal end. The throughbore closely receives the plastic cap. The throughbore having a chamfer where it opens onto the distal endface of the muzzle assembly to provide a nest for the bulge and to permit a proximal surface of the bracket to lie flat against the distal end surface  42  of the muzzle assembly. Because the bushing fits snugly onto the nail, the magnet on the distal face of the muzzle assembly can be eliminated if desired. 
     While certain preferred embodiments of the invention have been described herein, the invention is not to be construed as being so limited, except to the extent that such limitations are found in the claims.