Pilot bit guide device

Abstract

A guide device for pilot hole drill bits for use with hardware items having countersunk screw holes, wherein the device provides a drill bit holder which is reciprocably mounted in a body member on a drill axis and which is formed with an abutment end portion, wherein axial position adjustment structure is provided for allowing the end portion to contact the angled wall surfaces of a countersunk screw hole on a plane which is oriented normal to the axis of a screw hole and the drill axis, wherein the body member lies flat on the upper surface of the item.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field

[0002] This invention concerns drill bit guide devices or jigs and particularly those jigs which are to be employed for properly aligning a drill bit with the screw hole in a hardware item, such as is common in door hinges, latches and the like which have countersunk holes for flat head mounting screws. For such items, if the pilot hole for the screw is not drilled exactly in the center, i.e., axially of the countersunk hole, and if the pilot hole is not drilled exactly perpendicular, i.e., normally to the hardware item, the head of the screw will not be flush with the outer surface of the item when the screw is driven home. The purpose and utility of the present device is to permit one to drill a flat head screw pilot hole that is exactly centered in the countersunk screw hole and exactly perpendicular to the work surface. Also, the present device has universal utility for practically any size countersunk screw hole regardless of the angle and depth of the countersunk walls.

[0003] The usefulness of such guides or jigs is well described in the “Technical Field” description of U.S. Pat. No. 4,544,303, to wit:

[0004] “When flathead screws are used to attach workpieces to backings, extreme accuracy is necessary in the location and entry angle of the pilot holes, so that a jig would be indicated. For, as the heads of such screws are driven home into their countersunk orifice, the position assumed by the workpieces is irrevocably committed, with no compensating possible. When the workpiece is a hinge, an almost imperceptible error in hinge position could be multiplied by the moment arm of the door closure to result in a functional error at the latch side of the door.”

[0005] 2. Prior Art

[0006] The most relevant prior U.S. patent in this field known to Applicant is U.S. Pat. No. 4,544,307. The jig of this patent however, does not have universal application to countersunk holes and is stated as being specific to a particular workpiece. It is also characterized as having no moving parts. Such construction, as will be seen, is markedly different from Applicant's device.

[0007] Objects, therefore, of the present invention are: to provide a pilot hole drilling guide device which can be used for practically any size and contour of countersunk screw holes; and to provide such a device with structure for automatically axially centering a drill bit with a countersunk screw hole in a hardware item.

SUMMARY OF THE INVENTION

[0008] The above and further objects hereinafter appearing have been attained in accordance with the present invention which, in a broad embodiment, is defmed as a guide device for pilot hole drill bits for use with hardware items having countersunk screw holes, wherein the device provides a drill bit holder which is reciprocably mounted in a body member on a drill axis and which is formed with an abutment end portion, wherein axial position adjustment structure is provided for allowing said end portion to contact the angled wall surfaces of a countersunk screw hole on a plane which is oriented normal to the axis of a screw hole and the drill axis, wherein the body member lies flat on the upper surface of the item.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention will be further understood from the following description and drawings wherein the figures are not drawn to scale and certain structures are enlarged for clarity, wherein:

[0010] FIG. 1 is a top view of one embodiment of the present guide device;

[0011] FIG. 2 is a cross-sectional view of the embodiment of the guide device of FIG. 1 taken along line 2-2 of FIG. 1;

[0012] FIG. 3 is a cross-sectional view of a variation of the abutment end portion of the bit holder in use on a shallow angled countersunk screw hole, FIG. 4 is an enlarged cross-sectional view as in FIG. 3 showing use of the device shown in FIG. 3 in a sharply angled countersunk screw hole;

[0013] FIG. 5 is a cross-sectional view as in FIG. 3 showing use of the device shown in FIG. 3 in a countersunk screw hole angled the same as the abutment end portion of the drill bit holder;

[0014] FIG. 6 is a view as in FIG. 2 showing use of the device shown in FIG. 2 with a sharply angled countersunk screw hole;

[0015] FIG. 7 is a top view of a structural variation of the present guide device;

[0016] FIG. 8 is a cross-sectional view of the device of FIG. 7 taken along line 8-8 in FIG. 7; and

[0017] FIG. 9 is an enlarged cross-sectional view taken along line 9-9 of FIG. 8.

DETAILED DESCRIPTION

[0018] Referring to the drawings and with particular reference to the claims hereof, the present guide device for drilling a pilot hole into a substrate 11 comprises body means 10 having an upper surface means 12 and flat bottom surface means 14 lying in a plane 30 and adapted to sit flat on an outer or countersunk surface 16 of a hardware item 18 having one or more countersunk screw holes generally designated 19. A pilot drill bit holder 20 having an abutment end portion 22 and an adjustment end portion 24 is reciprocably threadedly mounted in bore means 26 which extends thru body means 10 from upper surface 12 to bottom surface means 14 on a reciprocation axis 28 oriented normal to plane 30 of bottom surface means 14. A drill bit lead aperture 32 is formed thru holder 20 on axis 28 for receiving a pilot hole drill bit 29. The abutment end portion 22 has a rim-like shoulder means 34 adapted to lie in a contact plane 36 oriented normal to axis 28 and is adapted to abut angled surface portions 38 of the countersunk hole 19 on plane 36 whereby the axis of the drill bit lead aperture and drill bit will lie normal to plane 36.

[0019] It is noted that plane 36 is a “floating” plane in the sense that its precise location along axis 28 is determined by bringing a rim-like shoulder means or rim line 34 into contact with surface portions 38 with screw hole 19 and aperture 32 being in axial alignment. The term “rim line” includes a line contact of the end portion 22 such as shown in FIGS. 3, 4, 6 and 8 as well as a full contact of 22 as shown in FIGS. 2 and 5. Also, the flat bottom surface means 14 of body 10 may comprise a single, unbroken surface, or may comprise spaced surface portions or ridges provided that the portions or ridges lie in the same plane such that when they contact surface 16, axis 28 will be perpendicular to surface 16.

[0020] The end portion 22 of holder 20 may be formed as a nose section 21 of slightly larger diameter than the rest of 20 as shown in FIGS. 3, 4 and 5 such that a well defined rim such as 40 or 42 of shoulder means 34 will contact or abut the angled sides or surface portions 38 such of the countersunk hole even if a perfect angle match of 22 and 38 as shown in FIG. 5 is not made. A circular recess 44 may be provided in body 10 to allow any desired clearance between the abutment end portion 22, body 10, and item 18 for ensuring proper seating of 22 in the countersunk hole 19.

[0021] In the operation of the embodiments of FIGS. 1 thru 6, preferably without bit 29 inserted into 32, and with holder 20 screwed axially upwardly a sufficient distance in body 10 so as not to allow the abutment end portion 22 to bottom out into screw hole 19, body 10 is placed flat onto upper surface 16 of item 18 with holder 20 approximately, i.e., eyeballed, axially aligned with screw 19 hole. Holder 20 is then screwed downwardly into the hole as the holder is slid back and forth or in a orbital manner in small increments across surface 16 until the operator feels that the holder is bottomed out in the screw hole and that body 10 is lying flat and firmly on surface 16. At this point, the operator can hold body 10 down against surface 16 in the aligned position and the drill bit held in a power drill then inserted into aperture 32 and operated to drill a pilot hole into substrate 11 to a desired depth.

[0022] A lock nut such as 46 may be threaded onto holder 20 and tightened against upper surface 12 of body 10 to fix the axial position of holder 20 in body 10. Such is particularly useful where a number of pilot holes are to be drilled for the same item whereby holder 20 might otherwise become inadvertently axially moved in the process. A leverage means may be provided on the adjustment end 24 of holder 20 to facilitate axially moving the holder in bore means 26. Such leverage means may comprise wrench flats 25 on end 24 as shown in FIG. 2, or hand operated torque arms 27 or the like fixed to 24 as shown in FIG. 1.

[0023] Referring to the embodiment of FIGS. 7-9, the body means 10 is provided with a bore 48 in which a piston or bit holder 50 is axially reciprocably mounted. A compression spring 52 in bore 48 continually urges piston 50 with, e.g., a one or two pound force, axially toward the hardware item. By means of this spring force and the counteracting force provided by the operator in sliding body 10 toward an axial alignment with the screw hole, a perfect axial alignment is automatically and essentially assured. It is noted that the non-conical shape of the abutment end portion 22 of this embodiment further assures that a firm and accurate contact of 22 with the countersunk wall surfaces 38 of practically any size and angled screw hole will occur.

[0024] Stop or shoulder means such as pins 54 fixed to the piston slide axially within slots 56 formed in body 10 and prevent axial movement of the piston in body 10 beyond that which would be required to bottom out the piston in the screw holes of any but the most unusual of hardware items.

[0025] In this embodiment, the body 10 can be made in two sections such as 58 and 60 such that the piston and spring can be placed within bore 48 and the two body sections then fastened together by machine screws 62 or the like. Also, body 10 can be of any size and configuration as long as it has the equivalent of the structure described and claimed herein, and may be provided with multiple bit holders such that multiple pilot holes can be drilled by a single placement of the body on an item.

[0026] The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications will be effected with the spirit and scope of the invention.

Claims

1. A guide device for accurately centering a drill bit thru a countersunk screw hole in an outer surface of a hardware item to be affixed at its inner surface by one or more screws to a substrate, said device comprising body means having an upper surface and a bottom surface means adapted to sit flat on said outer surface of said item, a pilot drill bit holder having an abutment end portion and an adjustment end portion and being reciprocably mounted in bore means in said body means, said bore means extending thru said body means from said upper surface thereof thru said bottom surface means and having a reciprocation axis oriented normal to a plane of said bottom surface means, a drill bit lead aperture extending thru said holder on said axis, said abutment end portion having rim-like shoulder means lying in a plane oriented normal to said axis and adapted to abut angled surface portions of the countersunk hole whereby the axis of said lead aperture will lie normal to said plane.

2. The device of claim 1 wherein said holder comprises a threaded sleeve member adapted to thread into mating threads in said bore means whereby the axial position of said sleeve member within said bore means can be adjusted to position said abutment end portion to abut angled surface portions of said countersunk hole when said bottom surface means of said body means is in flat contact with said outer surface of said item.

3. The device of claim 2 wherein said shoulder means comprises a peripheral rim line of a cone shaped abutment end portion.

4. The device of claim 2 wherein said shoulder means constitutes a peripheral rim line comprising the abutment end portion of a cylinder shaped, threaded drill bit holder.

5. The device of claim 1 wherein said holder comprises a cylinder shaped piston member mounted in said bore means for reciprocation on said axis, and pressure means on said body means and engaging said holder for urging said holder axially in said bore means to thereby extend said abutment end portion beyond said bottom surface means whereby, in the use of said device, said abutment end portion will first contact angled surface portions of said countersunk hole and then, by applying generally axially directed hand pressure on said upper surface of said body means, said bottom surface means will be moved into a flat contact position on said outer surface of said item.

6. The device of claim 5 wherein said shoulder means comprises a peripheral rim line of a cone shaped abutment end portion.

7. The device of claim 5 wherein said shoulder means constitutes a peripheral rim line comprising the abutment end portion of a cylinder shaped piston member.

8. The device of claim 5 wherein said pressure means comprises compression spring means mounted in said bore means, first shoulder means on said body means for engaging a first end of said spring means and holding said first end in a fixed axial position, a second end of said spring means engaging said holder, second shoulder means on said body means, third shoulder means on said holder axially spaced from said second shoulder means and adapted to engage said second shoulder means to prevent removal of said holder from said body means by action of said spring means.