Adjustable means of limiting driving depth with attachable nosepiece

Sept. 8, 1970 r. c. falter 3,527,273

ADJUSTABLE MEANS OF LIMITING DRIVING DEPTH WITH ATTACHABLE NOSEPIECE

Filed Jan. 24, 1968

<img file="US3527273A_D0001.tif" />

3,527,273

Patented Sept. 8, 1970

United States Patent Office

527 273

ADJUSTABLE MEANS OF LIMITING DRIVING DEPTH WITH ATTACHABLE NOSEPIECE

Ronald C. Falter, Columbia, S.C., assignor to Rockwell Manufacturing Company, Pittsburgh, Pa., a corpora- 5 tion of Pennsylvania

Continuation-in-part of application Ser. No. 585,824,

Oct. 11, 1966. This application Jan. 24, 1968, Ser. No. 700,168

Int. Cl. B25b 23/00

U.S. Cl. 144—32 4 Claims ^w

ABSTRACT OF THE DISCLOSURE

A tool including a detachable housing, an axially mov- 15 able, rotatable, work-performing component disposed in the housing, a clutch located in the housing which disengages to terminate rotation of the work-performing component when the work-performing component reaches a predetermined position longitudinally of the housing, 20 a detachable stop member adjustable axially of the housing for varying the distance that the end of the work performing component protrudes from the housing when the clutch disengages, a keeper for retaining the stop member in the position to which it is adjusted, and a remov- 25 able nosepiece which permits the work-performing component to· be removed from the tool without disturbing the depth adjustment.

This application is a continuation-in-part of application No. 585,824 filed Oct. 11, 1966 for Adjustable Means of Limiting Driving Depth With Attachable Nosepiece (which is now abandoned).

This invention relates to tools and, more specifically, 35 to tools for setting a fastener or boring or tapping a hole at a specific distance relative to a given work surface or the like. In particular, then, the present invention relates to novel improved tools with an arrangement for limiting the movement of the work performing tool ele- 40 ment relative to a given surface of a workpiece.

The principles of the present invention will be developed by relating them to drywall screwdrivers for the sake of convenience. The application of these principles to other types of tools will be obvious to those skilled in 45 the relevant arts from this description of an exemplary adaptation.

One important and primary object of the present invention is the provision of tools with novel, improved, depth limiting devices. ³⁰

In the depth limiting devices of the present invention by which the present and other important goals are achieved, a stop element threaded on the tool housing is employed to permit accurate adjustment of the depth limit. A spring biased keeper having locking portions en- 35 gageable with co-operating portions on the threaded member is employed to positively lock the latter against rotational movement relative to the tool housing.

Co-operating with the depth limiting device just described in the present arrangement is a clutch interposed 60 in the drive train between the tool motor and the screwdriver bit or other work performing component. In the case of a screwdriver type tool, for example, this clutch automatically disengages when the bit has set the screw at a specified depth determined by the stop element of the 65 depth adjusting mechanism.

Tools employing a combination of depth adjusting mechanism and co-operating clutch have heretofore been proposed. Exemplary of but by no means the only such tool is the Milwaukee Electric Tool Co. Catalog No. 70 6740-1 Drywall Screwdriver.

The novel tools of the present invention differ from those of the type described in the preceding paragraph in one important respect. This is that all of the components of the rotation effecting clutch mechanism are accessible merely by removing the housing on which the stop element of the depth adjusting mechanism is threaded. In the previously proposed tools of the same general type, in contrast, the driving or both the driving and driven clutch members are located in the main tool casing.

The advantage of applicant’s arrangement is than the clutch mechanism can be serviced much easier than is possible in the previously proposed tools. Accordingly, maintenance costs are potentially lower in the case of the present invention.

Another important advantage of applicant’s novel arrangement is that it permits the reduction gears interposed between the tool motor and the clutch to be isolated in a sealed chamber in the main tool casing. This is advantageous since it facilitates lubrication of the reduction gears and protection of the gears against dust and other foreign matter.

Still another advantage of applicant’s arrangement is that it facilitates the conversion of a drywall screwdriver to a regular drill and vice versa. For example, 'by merely replacing the detachable housing of the type described above with one equipped with a conventional chuck and a link for connecting the chuck to the output shaft from the reduction gears, a drywall screwdriver can be quickly converted to a conventional drill.

Another feature of the present invention is that it utilizes in the depth adjusting mechanism described above a nosepiece which can be readily removed and which, when removed, permits the tool to be used to back out screws which have already been set.

In the depth limiting devices of the present invention, by which the foregoing and other important goals are obtained, a stop element threaded on the tool housing is employed to permit accurate adjustment of the depth limit. A spring biased keeper with locking portions engageable with cooperating portions on the threaded member is employed to positively lock the threaded member against rotation on the tool housing. As a result, vibrational and other forces cannot alter the setting of the stop element.

This arrangement has a decided advantage over drywall screwdrivers and other tools equipped with different types of depth limiting devices. Specifically, in the case of a drywall screwdriver equipped with a conventional depth limiting device, the screw cannot be backed out with the screwdriver unless the depth limiting component is first retracted. This is because the stop element prevents the screwdriver from turning the screw once the latter has been set to the desired depth. In prior depth limiting devices the stop element cannot be retracted without then readjusting the device to its original setting to resume the driving of screws. This is decidedly disadvantageous since the time spent in readjusting the stop element is completely non-productive.

In the depth limiting devices of the present invention, in contrast, the nosepiece of the stop element can be removed and replaced without altering the depth adjustment when the circumstances dictate its removal, eliminating the time lost in readjusting the conventional depth limiting device.

Tools with removable nosepieces have heretofore been proposed, a typical example being the Millers Falls Company No. 9637 Drywall Screwdriver. However, it has not been known that by employing them with depth limiting mechanisms of the type contemplated by the present invention, the problem associated with the latter of backing out screws, etc. without disturbing the depth adjustment can be eliminated. Accordingly, the use of a removable

8,527,273 ³ nosepiece in the manner contemplated by applicant represents a significant advance in the art.

From the foregoing it will be apparent that other important but more specific objects reside in the provision of tools in accord with the preceding object:

(1) Which are significantly easier to service than heretofore known tools of a similar type.

(2) Which are more flexible than heretofore known tools of a similar type in that they can be readily converted from use in one type of operation to use in another type of operation.

(3) Which facilitate the sealing of gear reduction drives and similar drive train components.

(4) Which in screw driving and similar applications permit screws and the like to be backed out without disturbing the adjustment of the depth limiting mechanism.

Additional objects and advantages and other important novel features of the present invention will become apparent from the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawing, in which:

FIG. 1 is a partly sectioned side view of a drywall screwdriver equipped with a depth limiting device having the advantages of and constructed in accord with the principles of the present invention;

FIG. 2 is a section through the depth limiting device illustrated in FIG. 1, taken substantially along line 2—2 of the latter figures;

FIG. 3 is a section through the depth limiting device of FIG. 1, taken substantially along line 3—3 of the latter figure;

FIG. 4 is a section through the depth limiting device of FIG. 1, taken substantially along line 4—4 of the latter figure;

FIG. 5 is a side view of the depth limiting device in one of the positions to which it may be adjusted; and

FIG. 6 is a fragmentary side view of the depth limiting device in another of the positions to which it may be adjusted.

Referring now to the drawing, FIG. 1 illustrates a drywall screwdriver 10 equipped with a depth limiting device 12 constructed in accord with the principles of the present invention.

In addition to the components just mentioned, screwdriver 10 includes a casing 14 housing an electric motor (not shown) connected to a gear reduction drive having a rotatably mounted output shaft 16. The operation of the screwdriver motor is controlled by an on-off switch 18 and a switch 20 for reversing the direction of motor rotation. A lock with an actuator 22 is also preferably provided for locking motor actuating switch 18 in the “on” position.

The details of the components described briefly in the preceding paragraph are not part of the present invention. For this reason and because they may be of conventional construction, they will not be described to an appreciably greater extent herein.

In the present invention, a clutch input member 24 having teeth 26 formed on its forward face (see FIG. 1) is fixed to gear reduction drive output shaft 16 for rotation therewith and prevented from moving axially of the shaft as by a retainer 27 (see FIG. 4). Axially aligned with clutch input member 24 is a clutch output member 28. The output member has teeth 30 on its rearmost face. These are engageable with the teeth 26 on the clutch input member to provide a positive drive connection between the two clutch members.

Clutch output member 28 is rotatably journalled in an elongated cylindrical housing 32, which is threaded onto a mounting boss 34 at the front end of tool casing 14. A shouldered spacer 36 adjacent boss 34 provides a seal between tool casing 14 and housing 32. It also prevents housing 32 from being threaded on the boss so tightly as to damage casing 14, which will normally be fabri4 cated of a relatively soft material such as an aluminum alloy.

As shown in FIG. 1, clutch input member 24 is also housed in removable housing 32 and is accordingly accessible when the latter is removed. This arrangement accordingly simplifies servicing of the tool and also makes it possible to seal the gear reduction drive terminating in output shaft 16 within the main tool casing 14. As a result, the lubrication of the gear reduction drive and the sealing of its components against dust and other foreign matter is simplified.

Another advantage of the arrangement just described is that screwdriver 10 can be readily converted to a conventional drill, for example, simply by replacing housing 32 with one provided with a conventional chuck and a link for drive connecting the chuck to output shaft 16. Screwdriver 10 can of course be similarly converted for use in other types of operations.

Referring still to FIG. 1, clutch output member 28 is free to move axially in an enlarged cavity 38 in housing 32 between positions in which it is respectively engaged with and disengaged from clutch input member 24. In the illustrated disengaged position, an external shoulder 40 on the clutch member engages a co-operating internal shoulder 42 in housing 32. In the engaged position, the teeth 30 of the clutch output member are engaged with the teeth 26 of clutch input member 24.

Clutch output member 28 is biased toward the illustrated disengaged position by a coil spring 43, which surrounds gear reduction drive output shaft 16.¹ As shown in FIG. 1, the latter extends into a bore 44 through clutch output member 28, and opposite ends of spring 43 press against spring seats 46 and 48 formed on facing portions of the clutch output and input members.

Referring now to FIGS. 1 and 3, clutch output member 28 is provided, at its forward end, with a socket 50 in which screwdriver bit 52 is retained to drive connect it to clutch member 28. Socket 50 and the rear end of screwdriver bit 52 have matching polygonal configurations so that there is a positive drive connection between the clutch member and tool bit.

Screwdriver bit 52 is retained in socket 50 by a ball 54 seated in a concave annular seat 56 adjacent the rear end of the screwdriver bit. Ball 54 extends through an opening 58 in the forward portion of the clutch output member and is pressed against tool bit seat 56 by a spring member 60 disposed in a recess 62 in the forward end of the clutch member.

To drive a screw with screwdriver 10, the tip 64 of screwdriver bit 52 is engaged with the grooves in the screw head. Forward pressure is then exerted on tool casing 14 to move clutch input member 24 into driving engagement with clutch output member 28. Switch 18 is then depressed to actuate the screwdriver motor which, through the gear reduction drive, clutch input member 24, and clutch output member 28 rotates screwdriver bit 52 to drive the screw.

In driving screws into gypsum board and other materials, it is generally necessary to set the screw with its head flush or at a predetermined distance below the surface of the work piece into which it is driven. To accomplish this, drywall screwdriver 10 is provided with a novel depth limiting device 12 as mentioned above. Referring now specifically to FIG. 1, depth limiting device 12 includes two major components: a stop element 66 (actually an assembly in the present invention as will become apparent later) and a keeper element 68.

As shown in FIGS. 1 and 5, stop element 66 is threaded onto the forward end of housing 32. Rotation of element 66 on housing 32 accordingly moves the stop element axially of the housing, varying the distance between ¹ The need for a compression spring can be eliminated by providing inclined surfaces on the clutch members so that relative rotation of the members will force them apart in the absence of an operator-exerted force holding them in engagement.

3,527,273 the work contacting end 70 of the element and the end of screwdriver bit tip 64, as may be seen by comparing FIGS. 5 and 6. As will be described later, this is effective to vary the depth to which a screw will be seated by screwdriver 10.

Referring still to FIGS. 1 and 5, stop element 66 is ^apositively locked in the position to which it is adjusted by the keeper element 68 mentioned previously. This element is a cylindrical sleeve mounted on the forward end of housing 32 behind stop element 66. Keeper element ₁₀68 is free to move axially on the housing, but is prevented from rotating relative to the housing as by a setscrew 72 which extends through the keeper element into an elongated groove 74 cut in and extending axially of housing 32. ₁₅

As is best shown in FIG. 5, the forward end of keeper element 68 is provided with projections or teeth 76, which fit into co-operating and similarly configured notches or recesses 78 formed in the rear end of stop element 66. There are two teeth 180° apart and four recesses 90° 20 apart in the illustrated embodiment of the present invention. A larger number of teeth or recesses or both may, of course, be employed, if desired.

With projections 76 engaged in recesses 78, keeper element 68 and stop element 66 must necessarily rotate as 25 a unit. However, since rotation of the keeper element is prevented by setscrew 72, such engagement locks stop element 66 against rotation relative to housing 32, thereby positively retaining it in the position to which it is adjusted. 30

The arrangement just described positively prevents stop member 66 from being shifted out of adjustment by vibration or other external forces as commonly occurs in depth limiting devices in which friction is relied upon to lock the stop member in place. 35

Referring now to FIG. 1, keeper element 68 is biased toward stop element 66 by a compression spring 80 housed between co-operating internal and external recesses 82 and 84 in keeper element 68 and housing 32, respectively. As shown in FIG. 1, the ends of recesses 82 40 and 84 are spring seats against which the opposite ends of spring 80 press to bias keeper element 68 toward stop element 66. This arrangement is highly effective in maintaining keeper element 68 in locking arrangement with stop element 66. 45

At the same time, it permits the setting of the stop element to be easily and quickly adjusted. To accomplish this it is necessary only to retract the keeper element until teeth 76 clear recesses 78, rotate the stop element to the new setting, and release the keeper element (which 50 will then move forward under the influence of spring 80 into engagement with the stop element). Stop element 66 is then rotated a few degrees (if necessary) until teeth 76 drop into recesses 78 under the influence of spring 80.

The slight rotation which may be necessary to engage 55 teeth 76 in recesses 78 will not effect the setting to any appreciable extent. This is particularly true as the number of locking teeth is increased.

Referring again to FIG. 1, as screwdriver bit 52 is rotated in the manner described above, sinking the screw 60 driven by the bit further into the work piece, the work contacting end 70 of stop element 66 approaches and finally engages the surface of the work piece. With stop element 66 adjusted as shown in FIG. 5, for example, screwdriver bit 52 will continue to rotate at this point, 65 setting the screw deeper into the work piece. However, with the stop element abutted against the work piece, the tool cannot be moved forwardly to maintain clutch input member 24 in engagement with clutch output element 28. Accordingly, as the screw driven by bit 52 con- 70 tinues to sink deeper into the work piece, compression spring 43 will move the teeth 30 on the clutch output member 28 out of engagement with the teeth 26 on clutch input element 24. At this point, which will occur when the screw has been driven to the desired depth, the screw- 75 driver bit will cease to rotate. As will be apparent from the description of screwdriver 10 set forth above and a comparison of FIGS. 5 and 6, the distance between the work engaging end 70 of stop element 66 (and accordingly the work piece surface) and screwdriver bit 52 at which separation of the clutch members occurs can be readily varied by adjusting the stop element along housing 32 in the manner described previously.

At times, it may be necessary to remove a screw which has been set. When employing a tool equipped with a conventional depth limiting device, screw removal cannot be accomplished without altering the adjustment of the depth limiting device, which is decidedly disadvantageous. Specifically, it will be remembered that clutch members 24 and 28 separate to stop rotation of bit 52 when the screw driven by the bit reaches the desired depth. A similar declutching occurs in a tool equipped with a conventional depth limiting device. Accordingly, to permit re-engagement of the clutch members in a tool equipped with the conventional device, the work contacting stop element must be retracted so that the tool can be moved sufficiently far toward the work to re-engage the clutch members, which alters the depth adjustment of the stop element.

In the present invention, the necessity of readjusting stop element 66 to effect screw removal is overcome by the two-piece construction of this element, which includes an adjusting member 86 and a work contacting nosepiece 88. As shown in FIG. 1, adjusting member 86 is of cylindrical configuration and is provided with internal threads 90 engaging the threads on housing 32. The recesses 78 into which the projections 76 of locking element 68 extend are also formed in this member.

Nosepiece 88 is an elongated cylindrical member seated in an annular recess 92 at the forward end of adjusting member 86. The nosepiece is frictionally retained in place by an O-ring 94.

To remove a screw that has been set, it is only necessary to remove nosepiece 88, which does not require any retraction or other shifting of stop element adjusting member 86. Removal of the nosepiece permits tool 10 to be moved sufficiently far forward to engage clutch elements 24 and 28. Switch 20 may then be moved to its “reverse” position and switch 18 depressed to actuate the tool motor and back out the screw. Following this, nosepiece 88 can be quickly reseated on adjusting member 86 and the setting of screws resumed.

Another advantage of the novel two-piece stop element just discussed is that interchangeable nosepieces may be seated on the adjusting member. This is advantageous in that it permits a nosepiece to be selected which will not mar or otherwise damage the particular type of material with which it is in contact, for example. The removable nosepiece also makes it possible to use different types of screwdriver bits or other work contacting elements and substantially facilitates the replacement of these elements.

As will be apparent from the foregoing description and as mentioned above, the principles of the present invention may be readily adapted to tools other than drywall screwdrivers. By slight modifications of various components and substitutition of a different type of rotatable working element for the screwdriver bit employed in a drywall screwdriver, the invention described above can be readily adapted to drilling and tapping tools, stud setters, nut runners, and other tools where movement of the rotating work producing component to a particular depth is desired. Accordingly, such modifications of the present invention are fully intended to be covered in the appended claims to the extent that they are not expressly excluded therefrom.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended

3,527,273 claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.