A DRILL GUIDE

Abstract: A drill guide with a workpiece engaging foot (26) mounted for slidable movement along a direction parallel to the drilling axis of a portable hand held drill to which the guide (12) may be mounted, having a drill engaging collar (12) by which the guide is clamped to the drill at a point just behind the drill chuck. The workpiece engaging foot (26) is resiliently biassed (18) away from the collar (12) so as to provide a withdrawal force on completion of drilling, and said workpiece engaging foot (26) encircles a drill bit mounted in the drill when applied to a drill, with an open side to enable ready fitting of drills into a drill chuck.

Description: "A DRILL GUIDE" TECHNICAL FIELD OF THE INVENTION THIS INVENTION relates to a drill guide, and more particularly to a drill guide attachable to a portable electric drill. BACKGROUND ART Many different means of drilling holes are known, and the most universal is the hand held, portable drill fitted with an appropriate bit. The common electric hand held drill requires some exercise of skill if a good standard of work is to be realised, particularly when hole forming in thin sheet material and into hard curved surfaces. Drilling usually progresses under substantial application of pressure upon the tool bit, such that in sheet material breakthrough may result in an impulsive forward lunging movement of the bit as it cuts entirely through, carrying the bit through the material such that any twist of the tool as it is disengaged will cause cutting of the hole wall into oval, off- circular shapes. Starting holes, particularly on smooth curved surfaces, can be difficult with a portable drill. Similarly, with materials possessed of distinct variations in density as their grain varies, production of a hole at a particular point may be difficult should the tool tip attempt to slide off to a softer entry point. Thus, in most applications involving drilling with electric hand held drills, a more accurate result will be achieved when drill and workpiece are mounted firmly relative to one another. To this end a drill press is a standard workshop tool and a drill stand has become a popular accessory for use with portable, electric drills. However, these combinations are suited to a fixed work station; they are not portable constructions and the advantages of portability in electric drills is lost. When the workpiece cannot be brought to the drill stand the drill stand's superior performance is not available. OUTLINE OF THE INVENTION An object of the present invention is the 5 production of a drill guide for application with portable hand held drills which achieves the advantage of portability whilst obtaining the accuracy of a drill stand. Another object of the present invention is the production of a drill 10 guide which is readily applicable as an accessory to a range of standard portable drills. A further object of the present invention is a drill guide which achieves a good standard of excellence in hole parameters in application to a wide variety of materials. 15 An additional object of the invention is a drill stand which is simply and readily constructed. A still further object of the invention is the production of a drill stand which may achieve a range of additional desirable advantages such as giving a positive 20 indication of drill depth and even provision of an end stop to control the depth of a hole bored with a drill fitted with the drill guide. Further objects and advantages of the present invention will hereinafter become apparent. 25 The present invention seeks to achieve its • objects by provision of a drill guide for application to a portable hard held drill which comprises a drill guide support means for attaching said drill guide to said hand held drill in an operative position 30 thereon, mounting means and a workpiece engaging foot mounted upon said mounting means characterised in that said mounting means is slidably mounted to said support means to enable movement of said mounting means and the workpiece engaging foot fixedly mounted 35 at an end of said mounting means remote from said support means, relative to a drill tip mounted in said drill, the mounting means being resiliently biassed to a fully extended position and oriented to provide movement of said workpiece engaging foot along a straight line parallel to the axis of said drill. BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more readily understood and put' into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment thereof and wherein:- Fig. 1 is a side elevation of a drill guide according to the present invention; Fig. 2 is a front elevation of the drill guide of Fig. 1; Fig. 3 is a plan view of the driJ1 guide of Fig. 1; Fig. 4 is an underside view of the drill guide foot means of Fig. 1; and Fig. 5 is a view of the foot of Fig. 4 from above. METHOD OF PERFORMANCE In Fig. 1 is shown a drill guide comprised of a work engaging foot means 10 mounted upon an extensible mounting means 11 attached to drill guide support means 12. The drill guide's work engaging foot means shown in Figs. 1 and 2 may comprise a plate means 26 attached to the extensible mounting means 11 which may be two rods 16 and 15 inserted into holed formed therein. The plate 26 provides a workpiece engaging face 13. For drilling of round workpieces the plate means 26 may carry a groove 14 which serves to locate the foot upon small round pipes to ensure their accurate drilling. Various forms of the plate means 26 may be provided to enable a variety of work engaging surfaces for non-slip properties on smooth materials such as sharp projections to bite into and locate the foot on vertical wooden surfaces, or rubberised non-slip surfaces for smooth metallic surfaces. Various types of surfaces may be removably attached with appropriate screws, etc., to the lower surface of the plate 26. The work engaging foot means 10 is seen from beneath in Fig. 4 and above in Fig. 5 and its shape may comprise an open, horseshoe shape as illustrated to enable ready insertion and removal of drill bits whilst the drill guide remains attached to its hand drill. In Figs. 4 and 5, 15 and 16 indicate the location of the two rods 15 and 16 of the extensible mounting means 11. Figs. 1 and 2 show the layout of the mechanisms which may form the extensible mounting means 11. The extensible mounting means 11 may be constructed upon two rods 15 and 16 carrying the workpiece engaging foot means 10 at one end thereof and the drill guide support means 12 at a position towards the other end. The support means 12 may be slidably mounted upon the rods 15 and 16 and held at a set position by end 24. The position of the support means 12 may be adjustable along the length of the rods to accomodate various drill ' lengths, etc. Rod 16 may be marked with a scale (not shown) whereby the depth to which a drill bit has penetrated may be measured off at a suitable reference point. To provide for a fixed hole depth an end stop 19 may be provided with a connection such as a winged screw 20 to affix it at a desired position to rod 16. The rod 15 may be encircled by a spring 18 operative to push the foot means 10 away from the guide support means 12. Thus by pushing down on the guide support means 12, in use, spring 18 is compressed as foot means 10 is pushed towards guide support 12. The guide support means 12 is best seen in Figs. 2 and 3, and it may be fitted with a handle 30 CVPI for operation. Opposite the handle 30 is a circular opening 40, split at 41 to enable the opening to clamp down upon a portable hand drill case just behind the chuck thereof. The hole 40 is dimensioned to suit a chosen one of or a range of common power drills, and the drill is inserted and clamped with the chuck and a drill therein extending towards the foot 10. In this way the drill guide is carried upon the power drill and may be left permanently attached thereto. By pushing down on the power drill in use in the normal manner to contact the drill tip on a workpiece, spring 18 is compressed as the drill tip proceeds into the material . By leaving the drill guide attached to a power drill, the guide, which may be rugged in construction, becomes a protective " device against drills being broken should the drill be dropped. The action of the spring provides a retractive force on finishing of a drilled hole, whilst the guides action ensures straight positive drill tip action so that properly circular holes of required size are reliably formed in the thinnest of sheet materials. The above outlines some of the basic features of a drill guide according to the present invention. Various additional features may be incorporated into the basic elements set out above. These additional features enable an enhanced range of applications for the portable drill including; operation as a grinder for sharpening of drills and blades; operation as a router; operation as a shoulder brace; and the performance of various kinds of edge profiling. In order to be able to draw the drill over a surface in a router operation, a handle 61 mounted upon a shaft 60 inserted into hole 62 (Fig. 2) may be provided as an attachment to foot means 10. In such OMPI an operation stop 24 may be adjustable in position along rod 16 to lock the support means 12 between it and stop 19, locked by wing nuts 22 and 20 respectively, so as to hold the foot steady relative to the routing tool mounted in the portable drill. Handle 61 is then grasped to draw the tool across the surface. In order to provide an edge guide for proper control of the tool in a routing operation, an edge guide plate 65 mounted on slidable rod 66 passed through hole 67 {see Fig. 1) in foot 10 may be provided. This plate may be locked by a suitable locking screw such as is commonly done with a grub screw. In use plate 65 in Fig. 1 need only be turned down to engage over a workpiece edge and be locked in place to function as a guiding means. The handle 61 becomes a stand for the front end of a drill in its resting position on a bench to hold the chuck up above the bench so that tools such as grinding wheels may be inserted therein. With the stops 24 and 19 on rod 16 suitably locked against support means 12 to locate the foot relative to a grinding wheel in the chuck of a drill to which the guide is mounted, the wheel may be used to sharpen drill bits, blades, etc. In such an operation, the edges of the foot 10 or the guide 65 may be employed as rests for tools being sharpened. The guide 65 may be rotated into a suitable position for that purpose, and in Fig. 5 is shown a niche 68 in which drills may be rested to engage with a grinding wheel (not shown) . In Fig. 1, the handle 61 is shown upon a rod 60 angled upwardly at an angle of 45°. Where a hole to be drilled must enter a workpiece at this angle, the guide may be tilted over to rest on the handle so as to be guided at the right entry angle. Various rods with handles might be supplied for interchangeable insertion into the foot to enable a range of entry angles by preselection and use of an appropriately angled handle. In drilling operations the edge guide 65 may be disposed outwardly of the foot on its rod 66 to provide broad workpiece engagement when required. As seen in Fig. 2, the edge guide 65 need only be prov¬ ided with a depth matching that of the foot in one of the guide's orientations so that it may be slid to an outwardly disposed position so as to become an additional bracing surface during drilling. In Fig. 1, rod 15 is provided with a winged nut 23 at its end so that springs 17 and 18 which may each comprise a number of springs butted end to end, may be interchanged by removal of end stop 24, sliding of the rods from support 12, to release springs 18. In this way, by interchanging springs, the support means 12 may be biassed to a particular pos- ition relative to foot 10. By reversing the position of the guide upon the drill so that the foot extends back behind the drill, the foot can be employed as a shoulder rest for bracing of the drill in heavy duty applications which require it. In this application the stops 24 and 19 are employed. The handle 30 may be a plastic moulding, hollowed to serve as a storage point for drill bits with a suitable moulded closure in the end * to enable safe storage and ready access. While the above has been given by way of illustrative example only, many modifications and variations as would be apparent to persons skilled in the art may be made thereto without departing from the broad scope and ambit of the invention as herein set forth and claimed in the following claims. OM?I_

Claims: CLAIMS 1. A drill guide for application to a portable hand held drill which comprises a drill guide support means for attaching said drill guide to said hand held drill in an operative position thereon, mounting means and a workpiece engaging foot mounted upon, said mounting means characterised in that said mounting means is slidably mounted to said support means to enable movement of said mounting means and the workpiece engaging foot fixedly mounted at an end of said mountingmeans remote from said support means, relative to a drill tip mounted in said drill, the mounting means being resiliently biassed to a fully extended position and oriented to provide movement of said workpiece engaging foot along a straight line parallel to the axis of said drill. 2. A drill guide as claimed in Claim 1 wherein said workpiece engaging foot has a horseshoe like shape in a plane transverse to said mounting means and is positioned to encircle a drill piece mounted in the drill upon its entering into a workpiece with the open side of said horseshoe-like foot enabling mounting of drills within a portable hand held drill to which the guide is mounted. 3. A drill guide as claimed in Claim 2, wherein said foot is provided with a hand grip means by which the foot may be drawn sideways over a workpiece to perform the function of a router. 4. A drill guide as claimed in Claim 2, wherein said foot is provided with at least one V-shaped groove in the work engaging face thereof so as to enable the foot to be located on a round rod-like surface to be drilled. 5. A drill guide as claimed in Claim 3, wherein said foot is provided with an edge guide means to engage a workpiece edge and guide said foot during a router operation comprising an edge engaging surface OMPI and an extensible mounting thereof to enable selected positioning relative to the foot. 6. A drill guide as claimed in Claim 5, wherein said edge guide means is provided with support surfaces on which tools to be sharpened may be supported to engage with a grinding wheel mounted in a portable hand held drill to which the guide is mounted said edge guide means being mounted on a lockable, extensible and rotatable rod passed through said foot to enable its positioning relative to said foot. 7. A drill guide as claimed in Claim 1, wherein said mounting means comprise a pair of rods slidably engaged in suitable passageways through said support means for movement therethrough with spiral spring means being located on at least one of said rods to act in compression between said foot and said support when said workpiece engaging foot is pressed against a work piece in operation of said drill guide. 8. A drill guide as claimed in Claim 7, wherein at" least one of said rods is provided with a stop means to restrict the amount of permissible travel through said support means so as to set the depth to which a drill may enter a workpiece. 9. A drill guide as claimed in Claim 8, wherein said at least one rod is provided with two stop means thereon positioned on either side of said support means and relocatable relative thereto to enable locking of said support means at selected locations or the limiting of the range of travel of said support means. 10. A drill guide as claimed in Claim 3, wherein said hand grip means is provided upon a support rod angled off a side of said foot at a preselected angle and is configured to provide a stable support when said guide is tilted over to provide drilling of a hole at. said preselected angle. OMPI

Inventors: USKI ANTERO, USKI, ANTERO
Applicants: USKI ANTERO, USKI, ANTERO
Application year: 1983
Main classification: B23B45
IPC codes: B23B45, B25F5