Nailing gun

A fore chamber assembly of a nailing gun serially feeds nails by gravity through a channel into a firing chamber. A nail head fence prevents the heads of trailing nails from underriding the heads of preceding nails and getting more than one nail in the firing chamber. The fence is vertically adjustable to work on different thickness nail heads. A safety link prevents firing of the gun unless the gun abuts the structure to be nailed and in that attitude applies a friction lock to nails in the fore chamber to prevent kickback of these nails upon gun firing. This lock is through a sliding cam and lever that engages a resilient button that in turn engages some of the nails. A feed magazine has spaced rails defining a slot that accepts loose nails in any orientation so long as their heads are on the rails with the nail shanks in the slot. The magazine rails are secured together by a cover that overlies the slot and nail heads and depending flanges that attach to the rails. A keeper interdicts the firing chamber to engage a nail in the chamber and hold it in place, and retracts under the force of the nail driver against the bias of a spring upon gun firing.

BACKGROUND OF THE INVENTION 
The present invention relates in general to the art of nailing, and, more 
in particular, to the art of automatic nailing tools. 
Nails for years have been driven by hand-held hammers. In comparatively 
recent times nailing guns have become available. The guns are usually 
pneumatically powered, extracting energy from compressed air to drive 
nails at the command of a gun's operator. The guns have a body housing the 
passages, valving and pistons used in converting the pneumatic energy into 
the kinetic energy of the driver. A driver head of the gun has a firing 
chamber that receives individual nails and orients nails into the path of 
the driver. A magazine feeds nails to the chamber. 
The nails for automatic nailing guns have come either prepackaged or loose. 
Prepackaged nails are oriented with their axes in a plane, their heads 
overlapping, their shafts parallel, and their shafts held together by 
parallel plastic bands. A spring-loaded follower urges the banded nails 
towards the chamber of the gun. With the driving of each nail, a new nail 
advances into the chamber for subsequent driving. Prepackaged nails are 
more expensive than loose nails because of the requirement for packaging. 
Some prepackaged nails have a portion of their heads sheared off to avoid 
double driving, the head shearing is an additional fabrication expense. 
The packaging comes apart upon the driving of the nails and can make the 
work place slippery and hazardous. Spring-fed followers tend to buckle the 
nails that they are urging against, limiting the number of nails in a 
package of nails. 
Attempts have been made to overcome the disadvantages of prepackaged nail 
guns. One such gun is described in U.S. Pat. No. 4,136,810. That patent 
describes a loose nailing gun having a magazine that orients the nails in 
echelon fashion for feed into the firing chamber of a gun. Feed is by 
gravity. A dog in the firing chamber holds a nail there and retracts in 
response to a force applied to it through the nail head by the driver. 
A loose nail gun is also described in U.S. Pat. No. 3,504,840 to O. A. 
Wandel et al. The Wandel device has a magazine that has a worm that 
advances nails serially into the firing chamber of the gun. It maintains 
nail orientation and displacement by the restraint of the lands of the 
worm at the cost of complication, expense and weight. 
A third type of a loose nail gun is described in U.S. Pat. No. 3,491,932 to 
Novak. The Novak device utilizes a nail arrest of a toothed plate; each 
tooth has a ramp that permits nail advance and the retraction of the plate 
from the path of nails and a steep shoulder that prevents nail kickback in 
a direction opposed to nail advance. This nail arrest necessitates a wide 
magazine and is attendant with considerable mechanisms for its working. It 
is not responsive to free nails when the gun disengages from the workpiece 
in order to assure orderly advance of the nails. 
A fourth device is described in U.S. Pat. No. 3,820,705 to Beals. Beals 
shows a gravity-fed magazine that feeds nails into the driving chamber of 
the nail gun and holds them there through a spring-loaded detent. The 
weight of the nails is aided by a weight trailing the nails. There is no 
provision for nail arrest or for preventing a trailing nail from 
underriding the head of a nail in front of it. 
SUMMARY OF THE INVENTION 
The present invention provides an improvement for nailing guns that effects 
reliable gravity feed of loose nails into a firing chamber of gun and in a 
nail feeding mechanism for the gun. It has a fence or limit member that 
prevents nail heads from underriding preceding heads and double firing of 
nails. It also employs a kickback arrest means that engages nails, 
preferably upon the gun engaging the workpiece to be nailed, and prevents 
nails from traveling in a direction opposite from the feed direction. 
In one aspect, the present invention provides an improved nailing gun 
having a nose that includes a fore chamber assembly which serially passes 
nails through a channel into a firing chamber of the nose. A fence or 
limit of the fore chamber assembly lies above the channel and prevents 
trailing nail heads from underriding preceding nail heads and causing the 
double firing problem. This fence is vertically adjustable to accommodate 
different nail head thicknesses. In particular form, the fence includes a 
flat, continuous member pivotally mounted to the assembly near its 
entrance opposite the nose and an eccentric mounted nearer the nose so 
that the fence can be tilted with respect to the nail head path. The nail 
arrest couples directly to a safety link of the gun that prevents firing 
unless the gun nose rests against the workpiece being nailed. In 
particular form, the safety link carries a cam that engages a pivoted 
lever which in turn through a shoe presses against a resilient detent 
which in turn engages nails in the channel and provides the arrest. 
Preferably the detent is formed of a rubber-like material. A magazine for 
the gun includes two substantially parallel rails which define at their 
top a track for the under surfaces of nail heads and a slot between them 
so that nail shanks go between the rails in the slot with the under 
surfaces of the nail heads in engagement with tracks. A unifying cover 
overlies the tracks and is spaced from them to provide nail head 
clearance. The cover has alternate flanges that attach to alternate of the 
rails to secure the cover in place and the rails together. A clip at the 
tail of the magazine accepts a second auxiliary magazine of loose nails 
and directs the nails into the gun magazine. The tail end of the gun 
magazine has a latch that effects a secure engagement with the auxiliary 
magazine and permits feed from the auxiliary magazine into the gun 
magazine. The latch also serves the function of preventing nails from 
leaving the gun magazine through the tail of that magazine. 
A keeper pin in the firing chamber is biased in that direction by a 
resilient spring and interdicts individual nail heads in the chamber. The 
axis of the pin is at an acute angle to the axis of travel of the driver 
so that the driver produces a retraction force on the pin to force it out 
of the way of the nail while the nail is being driven. 
The safety link is spring-biased into a position that prevents gun firing 
and into a position where the nails of the position where the nail arrest 
is not engaged. The nails are substantially free to move within the fore 
chamber and magazine. This spring is overcome by the weight of the gun and 
the counteracting force of the workpiece on the safety link. As previously 
brought out, when the link is thus activated the nail arrest engages nails 
and prevents kickback during firing. 
These and other features, aspects and advantages of the present invention 
will become more apparent from the following description, appended claims 
and drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The general organization of the improved nailing gun is shown in FIG. 1. In 
that Figure the nailing gun 10 includes a gun proper 12, a nose assembly 
14, a prechamber assembly 15 and a magazine assembly 16. The gun proper is 
known and its description is not necessary, other than to say that it is a 
pneumatically operated tool that has a reciprocating pin-like driver that 
on a downstroke drives a nail under the power of pneumatic pressure. 
The magazine feeds by gravity serially oriented loose nails into the nose 
assembly. In the nose assembly, the nails in a feed channel are prevented 
from underriding nails that have preceded them by a nail fence 17, and 
nails are prevented from being kicked back in the direction of the 
magazine when the gun is applied to a workpiece in preparation for nailing 
by a nail arrest 18. 
Nose assembly 14 includes a safety link 19 that has a finger 20 for 
physically engaging the workpiece. The finger guides in a guide way 22 in 
a nose piece 24 of the nose assembly. The link extends with its major 
plane normal to the plane of FIG. 1 upwardly, and then laterally towards 
the viewer, and then, with its major plane parallel to the plane of FIG. 
1, upwardly and toward the magazine, past the nose assembly, over the 
prechamber assembly, and then, with its major plane normal to the plane of 
the Figure, up to a trigger 26 of the gun. The link has a safety lug 28 
preventing the trigger from rotating and firing while the link is in the 
position shown in FIG. 1 with finger 20 distended. When finger 20 engages 
a workpiece and withdraws flush with the bottom of the assembly and link 
18 translates upward, the trigger may be pulled to fire the gun. This 
aspect of the safety link is known. 
The safety link mounts a cam 30 attached to it that forms a part of the 
nail arrest, to be described in detail subsequently, but which serves to 
prevent nails from reversing direction and traveling towards the magazine 
upon firing of the gun, an anti-kickback quality, and which engages nails 
when the link has been translated by the gun pressing against a workpiece. 
A spring 32 between the gun body and safety link biases the safety link 
towards the safety engaged position in which the nail arrest is disengaged 
and the gun cannot be fired. 
FIGS. 2 and 3 illustrate the nose assembly in greater detail. Here, the 
safety link 19 is seen attached to finger 20 through a coupling slide 40. 
Guide way 22 in the nose tracks the finger and stabilizes the workpiece 
end of the link. The nose has a firing chamber 42 into which nails drop in 
preparation for firing. The chamber is on the axis of the driver of the 
gun which actually drives the nails. The firing chamber is interdicted by 
a detent pin 44 that is biased into the interdicting position by a spring 
46 housed in a cavity 48 of a detent mount 50. As can be seen in FIG. 4, 
the pin arrests nails in chamber 42 by contacting the shank of the nails 
and the under surface of the nail heads and keeps the nails in position 
for driving by a driver 52 of the gun. The detent pin has a cylindrical 
shank, a spherical nose and a distal flange. The latter acts as a limit to 
prevent excessive intrusion of the pin into chamber 42. Spring 46 is of a 
rubber-like material and biases the keeper against the limit of a shoulder 
of the nose assembly. 
The nose assembly has a track that maintains orientation of the nails in 
serial fashion ahead of the firing chamber and assures nail presence 
there. In greater particular, the track is defined by a ramp 54 that drops 
the nails into the firing chamber from the prechamber assembly. 
The prechamber assembly includes a horizontal track 56 ahead of ramp 54 in 
which heads are oriented so that they cannot stack with heads of following 
nails underlying heads of preceding nails. Track 56 maintains a serial 
order for the nails. In greater particular, prechamber assembly includes 
parallel side plates 58 that are spaced apart to define a channel 62 for 
nail shanks but which are sufficiently close together to define 
complementary tracks 60 for engaging the under surfaces of nail heads, 
keeping the nails on their track. This arrangement can be seen in FIG. 3 
most readily. The side plates attach to the nose assembly through mounting 
flanges 64 and threaded male fasteners 66. 
A nail head limiting fence assembly 17 prevents the underriding of the 
preceding nail heads. This fence includes a continuous elongated fence 
member that extends from the entrance to the fore chamber to an end over 
ramped section 54. The fence member has a pilot portion 74 that flares 
open in the direction of the magazine to guide nail heads onto tracks 60. 
The fence is pivotally connected to the side plates through a mounting 
bracket 76 and a pivot pin 78 at the end of the fence opposite the firing 
chamber so that the end of the fence closest to the firing chamber may be 
vertically adjusted to adjust the distance between the fence and rails 60. 
This adjustment is effected through an eccentric 80 acting between the 
mounting bracket and fence. In greater particular, and with reference to 
FIG. 3, eccentric 80 comprises an eccentric journal 82 acting on a 
circular follower surface 84 of the fence member in an upstanding flange 
86 of that member. The eccentric is journaled at journals 88 and 90 in the 
mounting bracket. An hexagonal head 92 provides for purchase of a 
wrenching tool to operate the eccentric. A lock nut 94 at the opposite end 
from the adjustment head secures the mechanisms together. The mounting 
bracket includes two parallel plates 92 welded to side plates 58. An 
access keyhole 94 in one of these plates permits mounting of eccentric 80. 
Thus, the fence, by merely adjusting the angular position of head 92, 
alters the vertical position of continuous fence member 72 above tracks 60 
to accommodate different sized nail heads and prevent undesirable stacking 
that produces double driven nails. 
Nail arrest 18 mounts to one of the side plates 58 through a mount 98. It 
includes a lever 100 pivotally connected to the mount at 102. The lever 
engages a shoe 104 and a rubber button 106. The button has a finger 108 
located in a hole in the side plate and which can go into the nail shank 
channel between the side plates to effect nail arrest. A slide 110 mounted 
to safety link 19 has a camming surface 112 that cooperates with a facing 
and complementary camming surface of the lever to effect depression of the 
button and the locking of the nails against kickback when the safety link 
is raised by finger 20 engaging a workpiece. 
As seen in FIGS. 1 and 5, magazine 16 consists of a pair of spaced-apart 
and parallel rails 120 secured together through roof 122 by alternate 
mounting flanges 124 and 126 that are welded to alternate of the rails. 
The cover prevents nails from leaving the magazine out its top. The 
mounting flanges of the cover effect a unity of rails and the roof. The 
top of the rails define tracks for the undersurface or nail heads. A 
handle 130 between the but of the magazine and the gun proper secures the 
magazine firmly to the gun. At the but end of the magazine, a clip 134 
permits attachment of an auxiliary magazine to feed additional nails to 
the gun. The clip bridges the space between the rails and has a latch 136 
mounted in it. The latch includes a tab 138 that extends above the surface 
of the clip and down through a hole into it. A diagonally extending tongue 
140 rests on the track surface of the rails. This downwardly depending 
tongue prevents nails from backing out the rails when it is in the 
position shown. When the auxiliary magazine is in place, this downwardly 
depending tongue rests on the under surface of upwardly flared roof 
portion 142 of roof 122 and permits the passage of nails unencumbered 
between the auxiliary magazine and the illustrated magazine. 
This invention effects the feeding of loose nails in an organized fashion 
through a magazine, into a prechamber assembly, and ultimately, one at a 
time, into the firing chamber of the nailing gun. This is done without 
underlapping of preceding nail heads by following heads. This is done 
while arresting nails during the drive cycle from kicking back in a 
direction opposite that of feed. All of the prechamber and its attendant 
nail arrest and nail head fence are of simple construction. The nail fence 
is adjustable to accommodate different height nails heads in the function 
of preventing underriding. The nail arrest occurs in connection with the 
freeing of the gun's trigger upon engagement of the nose of the gun with 
the workpiece to be nailed. The arrest is done through a very simple cam 
arrangement and a resilient button. 
The present invention has been described with reference to a preferred 
embodiment. The spirit and scope of the appended claims should not, 
however, necessarily be limited to the foregoing description.