Guide for fastener driving tool

A guide assembly mounted on a fastener driving tool locates the tool a predetermined distance from the edge of hardboard siding or a similar workpiece and assures that a fastener is driven into the workpiece the correct distance. The tool includes a housing having a nose defining a drive track and a driver blade for driving fasteners along the drive track into the workpiece. A safety member moves relative to the housing between a workpiece responsive position extending beyond the nose and an operating position, and a spring urges the safety member toward the workpiece responsive position. The guide assembly includes a yoke with a central portion adjustably mounted to the safety for controlling fastener penetration. A pair of laterally extending arms carry edge guides to locate the tool spaced from the workpiece edge in either of two different tool orientations. The edge guides are retractable so that one may be retracted when the other is used, or so that both may be retracted if neither is used. The edge guides are biased to a projecting position with a force smaller than the safety biasing spring force so that the guide assembly does not interfere with operation of the safety.

The present invention relates to fastener driving tools and more 
particularly to a guide assembly for locating a power fastener driving 
tool relative to a workpiece. 
BACKGROUND OF THE INVENTION 
A typical pneumatic fastener driving tool includes a housing having a nose 
portion that is located relative to a workpiece at a position where a 
fastener, such as a nail, is to be driven. When the tool is placed against 
the workpiece, a movable safety member enables a drive stroke in which a 
driver blade drives a fastener along a drive track through the nose and 
into a workpiece. Usually the tool is designed so that the fastener 
penetrates fully into the workpiece with the head of the fastener 
countersunk to some degree. 
Among the many uses to which fastener driving tools have been put is the 
installation of siding in the construction industry. Because of its 
advantages over conventional wood siding and other alternative materials, 
preformed hardboard siding is becoming more popular. Standard nailing 
techniques can lead to difficulty in the installation of hardboard siding. 
For example, countersunk fastener heads can cause fracturing of the fibers 
of the hardboard material at the exposed surface and a reduction in the 
life of the material or its surface finish may result. In addition, 
hardboard siding material is designed for optimum performance with 
fasteners installed a predetermined distance from the edge of the siding, 
and carefully controlled positioning is desirable. 
A typical power fastener driving tool may cause difficulties in the 
installation of material such as hardboard siding because the tool cannot 
be controlled to precisely vary fastener penetration into the workpiece. 
In addition, the tool cannot readily be located at a precisely determined, 
optimum position relative to the siding material. While a simple, fixed 
edge guide might be employed, this approach would limit use of the tool to 
a single orientation relative to the workpiece and would prevent use of 
the tool for other purposes or at other locations on the workpiece. 
SUMMARY OF THE INVENTION 
It is a principal object of the present invention to provide a guide 
assembly for fastener driving tools capable of adjustably regulating the 
degree of fastener penetration into a workpiece while accurately locating 
the fastener without restricting tool orientation to a single choice. 
Other important objects of the invention are to provide a guide assembly 
suitable for use with widely used existing fastener driving tools; to 
provide a guide assembly capable of conveniently being mounted to the 
movable safety of a fastener driving tool without interfering with the 
operation of the safety or the tool; to provide a guide assembly that is 
adjustable for different degrees of fastener penetration; and to provide a 
guide assembly that can be associated with a fastener driving tool to 
overcome problems encountered in the installation of hardboard siding and 
similar materials. 
In brief, the above and other objects of the invention are realized by 
providing a guide assembly for use with a fastener driving tool of the 
type including a housing having a nose defining a drive track and 
including a driver element for driving the fasteners in a given direction 
along the drive track into a workpiece. The tool employs a safety member 
carried by the housing for movement relative to the housing in the given 
direction between a workpiece responsive position and an operating 
position. Biasing means urges the safety toward the workpiece responsive 
position. 
The guide assembly of the present invention includes a guide member and 
adjustable mounting means supporting the guide member adjacent the nose of 
the fastener driving tool for adjustably mounting the guide member in a 
selected one of a range of positions along the given direction for 
limiting the depth to which a fastener is driven into the workpiece. An 
arm extends from the nose in a direction transverse to the given 
direction, and an edge guide carried by the arm extends in the given 
direction beyond the safety member for locating the nose a predetermined 
distance from an edge of the workpiece.

DETAILED DESCRIPTION 
Having reference now to the drawings, FIG. 1 shows a fastener driving tool 
generally designated as 10 equipped with a guide assembly generally 
designated as 12 and constructed in accordance with the principles of the 
present invention. The features of the present invention are applicable to 
many different types of fastener driving tools used with many different 
types of workpieces. The drawings illustrate the preferred embodiment in 
which tool 10 is a pneumatically powered tool for driving round head nails 
14 into a workpiece 16 comprising prefabricated hardboard siding. 
Tool 10 is shown in FIG. 1 in somewhat simplified and schematic form since 
additional details of the tool are not necessary to an understanding of 
the present invention. A housing 18 includes a handle 20 and a head 
portion 22 in which a piston 24 carrying a depending driver blade 26 is 
mounted for reciprocal movement in a fastener drive direction. A magazine 
28 carries a supply of fasteners 14. 
A fastener drive track 30 (FIG. 3) is defined in a nose 32 of the tool 10. 
A fastener feeding gate 34 is operated in synchronism with piston 24 to 
position a single fastener 14 in the drive track 30 prior to each drive 
stroke. Fasteners 14 may be supplied in collated form mounted along the 
length of a tape or carrier, and a tape guide 36 guides the tape away from 
tool 10 after fasteners have been driven therefrom. 
Operation of the tool 10 in a fastener driving stoke is controlled by a 
trigger 38 and a safety 40. The safety includes a head portion 42, a bias 
spring mounting tab 44, a guide leg 46 and an actuating foot 48. Safety 40 
is mounted on the housing 18 of tool 10 for limited movement in the 
fastener driving direction parallel to the drive track 30. Head portion 42 
slidingly engages the nose 32 (FIG. 3) and a guide pin 50 fixed with 
respect to the housing 18 is slidably received in a slot 52 formed in the 
guide leg 46 of safety 40. A safety biasing spring 54 biases the safety to 
the normal, workpiece responsive position shown in FIG. 1 in which the 
nosepiece projects beyond the end of the nose 32. 
A fastener driving stroke is initiated when safety 40 is moved to an 
alternate operating position and the trigger 38 is depressed. When the 
tool is pushed against the workpiece 16 with a force larger than the 
biasing force of the spring 54, the spring 54 is compressed and the 
actuating foot 48 moves toward a trigger base or housing 56. A rod 58 
moves into the trigger base 56 and operates in conjunction with trigger 38 
to control a pneumatic valve system to carry out a fastener drive stroke 
and a fastener feeding operation. 
The preceding description of the fastener driving tool 10 is ample for a 
complete understanding of the present invention. For further details of 
operation of fastener driving tools of this type, reference may be had to 
the descriptions set forth in the following Unites States patents, each of 
which is incorporated here by reference. 
U.S. Pat. No. 4,784,308 (patent application Ser. No. 847,726, filed Apr. 3, 
1986) describes a pneumatic valving operation for carrying out a fastener 
driving stroke and a fastener feeding stroke in a pneumatic fastener 
driving tool. U.S. Pat. No. 3,543,987 and U.S. Pat. No. 4,319,705 describe 
pneumatically operated arrangements for feeding fasteners one at a time 
from a magazine to a fastener drive track in synchronism with operation of 
a fastener driving tool. U.S. Pat. No. 4,264,028 and U.S. Pat. No. 
4,405,071 disclose arrangements for the operation of a fastener driving 
tool in response to actuation of a trigger and a safety. 
Guide assembly 12 can readily be mounted to the tool 10 or other fastener 
driving tool either during original manufacture or by retrofitting. The 
assembly 12 includes a guide member in the form of a shoe or yoke 60 
carried by the head 42 of safety 40. A mounting block 62 having a pair of 
tapped holes 64 is attached to the front of head 42 by welds 66. A pair of 
fasteners 68 are threaded into holes 64 to secure the member 60 in place. 
In order to permit adjustment of the degree of fastener penetration, the 
member 60 is mounted for adjustment relative to the safety 40 and tool 10. 
When the tool is placed against workpiece 16, a bottom edge or surface 70 
of member 60 engages the workpiece. When the tool is moved relative to the 
workpiece to displace the safety 40 and initiate a fastener driving 
operation, the distance between the end of nose 32 and the workpiece 18 is 
determined by the adjusted position of the member 60. The adjustment is 
provided by a pair of slots 72 in member 60 receiving the fasteners 68. 
The fasteners may be loosened and retightened with the member 60 in a 
selected position relative to the safety 40 and tool 10. 
A pair of arms 74 extend laterally in opposite directions from a central 
portion 76 of member 60. Each arm carries a retractable edge guide 78 
permitting the tool 10 to be accurately positioned with drive track 30 
located a precisely determined distance from an edge 80 of workpiece 16. 
Each arm 74 includes a cylinder or sleeve 82 attached by welds 84 to 
opposite edges of the central portion 76 of guide member 60. Sleeves 82 
are each parallel to the drive track 30. 
Each edge guide 78 is a generally cylindrical element having a head portion 
86 and a shank 88 captured within the corresponding sleeve 82 by a 
fastener 90 (FIG. 4). Each edge guide 78 is biased outwardly from sleeve 
82 by a guide biasing spring 92. When head portion 86 of an edge guide 78 
is pushed against workpiece 16, the spring 92 contracts and the edge guide 
78 retracts to the plane of the bottom edge 70 of the guide member 60. 
Preferably the edge guides 78 are formed of a low friction material such 
as plastic or the like and may rotate within the sleeve 82 to limit 
friction as the guides are moved along an edge 80 of workpiece 16. 
Operation of the guide assembly 12 of the present invention appears in 
FIGS. 6 and 7. In order precisely to space a fastener from workpiece edge 
80, the tool and guide assembly 12 are located as shown in FIG. 6. A 
selected one of the two edge guides 78 is in contact with the workpiece 
edge 80 and as a result the drive track 30 is precisely located a desired 
distance from the edge 80. Since two edge guides 78 are employed in a 
symmetrical configuration, the tool 10 may be held in the more convenient 
of two alternative orientations, one hundred eighty degrees apart. This 
feature is important in making the tool 10 with the guide assembly 12 
convenient to use on a job site. 
The guide biasing springs 92 have a smaller biasing force or spring force 
than the safety biasing spring 54. Thus, as seen in FIG. 6, the tool may 
be placed in position for operation without compression of the safety 
biasing spring 54 or movement of the safety 40 relative to the housing 18. 
Preferably, the springs 92 are selected so that both springs 92 may be 
fully compressed before compression of the safety biasing spring 54 
occurs. This permits the tool to be used at any location on workpiece 16 
without the guide assembly 12 interfering with operation of the tool or 
the safety 40. 
After the tool 10 and guide assembly 12 are positioned in preparation for a 
drive stroke as illustrated in FIG. 6, the drive stroke may be initiated 
in the usual manner by pushing the tool against the workpiece to move the 
safety from the extended position on FIG. 6 to the operating position of 
FIG. 7, and by operation of trigger 38. The conclusion of a fastener 
driving stroke is shown in FIG. 7. The head 94 of fastener 14 is 
accurately driven flush with the surface of workpiece 16. In the case of 
hardboard siding, this flush penetration avoids problems that can arise in 
a countersunk installation due to exposed fractured fiber surrounding the 
fastener head. This accurate penetration is achieved by adjustment of the 
guide member 60 relative to the safety head 42 as described above. 
FIG. 8 in comparison with FIG. 2 illustrates a different adjusted position 
of the guide assembly 12. In FIG. 8 the guide assembly is adjusted to 
extend further from the tool 10 and the nose 32. When the tool 10 is 
operated with guide assembly 12 adjusted as shown in FIG. 8, a fastener 14 
will penetrate less deeply into workpiece 16. Alternatively, the assembly 
12 may be adjusted so that member 60 projects less far from nose 32 than 
shown in FIG. 2. This adjustment makes possible a countersunk installation 
of a fastener 14 into workpiece 16. 
While the invention has been described with reference to details of the 
embodiments shown in the drawings, these details are not intended to limit 
the scope of the invention as defined in the following claims.