US3838935A

US3838935A - Drill guide

Info

Publication number: US3838935A
Application number: US00387471A
Authority: US
Inventors: A Boyajian
Original assignee: BOYAJIAN ALFRED
Current assignee: BOYAJIAN ALFRED
Priority date: 1973-08-10
Filing date: 1973-08-10
Publication date: 1974-10-01
Anticipated expiration: 1991-10-01
Also published as: DE2438690A1; JPS5049792A; GB1489240A; CA1021965A; FR2240066A1

Abstract

A drill guide comprising a base, post fixed to the base, a carriage mounted on the post for movement toward and from the base, and an adjustable coupling on the carriage for securing a power drill thereto with the axis of the drill at a predetermined angle to the base, said carriage being adapted to be removed to enable using the drill independently of the base and to be restored without readjustment to said predetermined position. The coupling supports the drill forwardly and laterally of the post substantially centered with respect to the base and the base contains an opening through which the drill may be lowered into engagement with the work. There is means in the form of a second post for guiding the carriage as it is raised and lowered, a spring yieldably supporting the carriage above the base for movement toward the base, and means for limiting downward and upward movement of the carriage relative to the base. A gauge plate is adjustably mounted on the base below the opening and has on it intersecting gauge marks adapted to be aligned with the axis of the drill. A platen corresponding in configuration to the opening in the base is hingedly supported in the opening in which position its surface is flush with the surface of the base and for movement from the opening to a folded back position away from the opening.

Description

United States Patent [1 Boyajian Oct. 1,1974

[ DRILL GUIDE [76] lnventorz Alfred Boyajian, PO. Box 811, Manhattan Beach, Calif. 90266 22 Filed: Aug. 10, 1973 21 Appl. No.: 387,471

Primary Examiner-Francis S. Husar Attorney, Agent, or FirmDike, Bronstein, Roberts, Cushman & Pfund [5 7] ABSTRACT A drill guide comprising a base, post fixed to the base, a carriage mounted on the post for movement toward and from the base, and an adjustable coupling on the carriage for securing a power drill thereto with the axis of the drill at a predetermined angle to the base, said carriage being adapted to be removed to enable using the drill independently of the base and to be restored without readjustment to said predetermined position. The coupling supports the drill forwardly and laterally of the post substantially centered with respect to the base and the base contains an opening through which the drill may be lowered into engagement with the work. There is means in the form of a second post for guiding the carriage as it is raised and lowered, a spring yieldably supporting the carriage above the base for movement toward the base, and means for limiting downward and upward movement of the carriage relative to the base. A gauge: plate is adjustably mounted on the base below the opening and has on it intersecting gauge marks adapted to be aligned with the axis of the drill. A platen corresponding in configuration to the opening in the base is hingedly supported in the opening in which position its surface is flush with the surface of the base and for movement from the opening to a folded back position away from the opening.

28 Claims, 13 Drawing Figures FATENTED BE? 7 74 mama FIG.|

FIG.6

FIG.4

PATENTEU 3.838.935

sum w 4 FIGJB DRILL GUIDE BACKGROUND OF THE INVENTION Drill guides for supporting and steadying a power drill for drilling workpieces are numerous in the art as illustrated in such US. Pat. Nos. as Pugsley, 2,997,900, Halbreich, 1,316,027 and 1,316,028, Shulters, 2,883,891, Daniels, 2,831,376, Jepson, 2,909,085 and 2,680,435, and others.

The drill guide of this invention while embodying in general the structural make-up of the drill guides disclosed in the aforesaid patents is designed to enable accurately disposing the drill with the axis of the bit at a predetermined angle with respect to the work, remove the drill from the guide for use independently thereof and replace it in said predetermined position without readjustment; to enable accurate alignment of the axis of the drill with intersecting center lines drawn on the work at the intersection of which a hole is to be drilled; and to enable using the drill guide at times as a drill press.

SUMMARY The drill guide of this invention comprises a base, a carriage, means mounting the carriage on the base for movement toward and from the base, said carriage being removable from said mounting means, a coupling mounted on the carriage for movement therewith to which a power drill together with a drill bit is adapted to be secured, and spring means yieldably supporting the carriage above the base for downward movement toward the base, said coupling being characterized in that it is adjustable on the carriage to dispose the drill in a predetermined position with the axis of the drill bit disposed at a predetermined angle to the base such that after such adjustment the carriage may be removed from the mounting means to enable using the drill independently of the supporting base and replaced without having to make readjustment to restore the drill bit to said predetermined position. The means supporting the carriage on the base comprises a post fixed in an upright position to the base and the means for yieldably supporting the carriage above the base is a coiled spring disposed on the post between the carriage and the base. There is a second post secured in an upright position to the base withwhich the carriage is slidably engaged and there is on the second post means for limiting the downward movement of the carriage on the base and means for limiting upward movement thereof. The coupling means may comprise a universal joint; for example, a ball and socket connection. Optionally, the coupling is comprised of horizontally aligned screws extending through the carriage and threaded into the coupling and vertically aligned screws threaded through the carriage above and below the horizontally aligned screws and abutting the coupling. The posts are fixed to the base along one side and the coupling supports the drill between the posts with respect to the front and back of the base and substantially midway between the sides thereof so as to be substantially centered on the base. The base contains an opening below the bit which affords access of the drill bit to the work, affords the operator a clear view of the workpiece, hole locating lines, gauge lines, facilitating matching of the hole locating lines with the gauge lines. A gauge plate is mounted on the base below the opening on which there are intersecting gauge lines adapted to be adjusted to align the intersection of said lines with the axis of the drill bit. To avoid parallax the gauge lines extend down to the surface of the work. A platen corresponding in configuration to the opening in the base is hingedly supported in the opening, in which position its surface is flush with the surface of the base and for movement from said opening to a folded back position in whichit rests on the base rearwardly of the opening. The platen when disposed in the opening adapts the drill guide to use a drill press.

The invention will now be described in greater detail with reference to the accompanying drawings wherein:

FIG. I is a perspective view of the drill guide as used for drilling holes in workpieces upon which it is positioned showing a power drill and bit mounted thereon in dot and dash lines;

FIG. 2 is a perspective view of the base of the drill guide showing the base converted to use as a drill press;

FIG. 3 is a perspective view similar to FIG. 2, showing the posts which mount the carriage for the power drill disposed transversely of the base rather than longitudinally thereof;

FIG. 4 is a plan view of one form of gauge plate;

FIG. 5 is an alternative form of gauge plate;

FIG. 6 is still another form of gauge plate;

FIG. 7 is a section taken longitudinally of FIG. I on the line 7-7 of FIG. 1, showing the base of the drill guide with the platen folded back so as to enable its use as a drill guide;

FIG. 8 is a corresponding view showing the platen folded forwardly for use of the drill guide as a drill press;

FIG. 9 is a plan view of FIG. 7;

FIG. 10 is an elevation, to somewhat larger scale, taken at the left side of FIG. 1, showing one form of coupling to dispose the axis of the drill perpendicular to the base and to the work support;

FIG. 10a is an elevation of the coupling taken on the line l0al0a of FIG. 11;

FIG. 11 is a view partly in section and partly in elevation taken on the line 11-11 of FIG. 10;

FIG. 12 is a plan view of a ball and socket coupling; and

FIG. 13 is an elevation of the ball and socket coupling shown in FIG. 12.

Referring to the drawings (FIG. 1) the drill guide comprises a substantially rectangular base 10 along one side of which are mounted two

posts

22 and 24, a carriage 30 mounted on the posts for movement to and from the base and a coupling 49 adjustably attached to the carriage for securing a power-driven drill 14 together with a drill bit 15 mounted in the chuck of the drill.

The post 22 is of circular cross-section and its lower end is set into a hole 25 (FIG. 7) drilled into the base and secured therein, for example, by a set screw 29. The post 24 is of non-circular cross-section having dia metrically disposed flat surfaces 26-26 which are parallel to the sides of the base and arcuate portions 28-28 which are threaded. The lower end of the post 24 is screwed into a threaded hole 27 in the base. The

posts

22 and 24 are parallel to each other and to the sides of the base and the one constitutes a support for the carriage and the other a guide and means for limiting the downward movement of the carriage toward the base and the upward movement of the carriage from the base. The aforesaid means comprises a pair of nuts '44 threaded onto the post 24 below the carriage and a nut 42 threaded onto the post above the carriage. The post 24 may, if desired, be of circular cross-section.

The carriage 30 (FIGS. 1, 10 and 11) comprises a block 31 having at one end vertically spaced arms 3232 containing aligned openings 3434 for slidably receiving the post 22 and at its other end a bifurcate 36 comprising spaced tines 3838 adapted to slidingly receive the post 24. A coiled spring 40 mounted on the post 22 between the base and the carriage yieldably supports the carriage at the upper ends of the posts against the stop 42, permitting the carriage to be moved downwardly by application of pressure to the power drill attached to it.

The adjustable coupling 49 for attaching the drill to the carriage block 31 is designed to support the power drill in a position with the axis of the drill chuck and the bit mounted therein substantially midway between the

posts

22 and 24 and substantially midway between the opposite sides of the base so that the drill bit is substantially centered on the base and so that downward pressure applied to the drill in use will not tend to overturn the drill guide. Additionally the coupling is designed to enable disposing the drill with-the axis of the drill bit at a predetermined angle to the base and to the work on which the base rests independently of any lack of precision in the manufacture of the drill guide, the drill and- /or the drill bit so as to enable manufacture without maintaining high precision which would increase the cost of the device and further to enable removing the power drill together with the coupling and the carriage from the post and using it independently of the drill guide for conventional drilling operations and then replacing it on the post for use in combination as a drill guide without having to make readjustments to restore it to the predetermined position of adjustment initially made. To insure this usage of the power drill independently of the drill guide the carriage and coupling are made as small as feasible and mounted to the housing of the drill at the outer side with respect to the normal use of the drill so as not to interfere with drilling operatrons.

To enable disposing the drill at the aforesaid predetermined position the adjustable coupling 49 is designed to enable making adjustments universally and in one form the adjustable coupling comprises, as shown in FIGS. 1, and 11, an attaching plate 51 adapted to be adjustably connected to the carriage block 31. The plate 51 has fastened to it by screws 46 an adapter 51.1 designed to extend around the housing of the drill and contains holes 51.2 for receiving bolts by means of which the drill may be fastened to the adapter. The carriage block 31 is provided with a pair of transversely spaced oversized smooth bore holes 4747 for receiving bolts 61-61 and the plate 51 is provided with correspondingly spaced threaded holes 6l.l61.1 for receiving the threaded ends of the bolts 616l. The carriage block contains also a pair of vertically spaced threaded holes 47.147.1 through which screw bolts 67-67 are threaded to engage the inner ends of the bolts with the plate 51. The oversized holes 4747 through which the bolts 61 extend permit the plate 51 to be rotated about a horizontal axis and to be fixed at any desired position by tightening of the screw bolts 6161 and the screw bolts 67-67 provide for rocking the plate 51 about a horizontal axis parallel to the carriage. Thus the structure provides for substantial universal adjustment of the axis of the drill and/or the drill bit relative to the base.

Alternatively, the adjustable coupling may comprise ball and socket means, as shown in FIGS. 12 and 13, wherein the coupling plate 51 has at one side a hemispherical protrusion 13 for engagement with a hemispherical recess 15 provided on the inner side of the carriage block 31. An oversized hole 17 is drilled from the inner side of the carriage block through the bottom of the hemispherical recess to the outer side. the outer end of which is counterbored to provide a hemispherical recess 19. A bolt 21.1 is mounted through the oversized hole 17 with a spherical washer 23.1 at its outer end and a pair of nuts 25.1 are screwed onto the bolt against the washer. A flat plate 27.1 is fastened to the plate 51 and the plate 27.1 is provided with openings 29.1 for receiving bolts 31.1 for fastening the drill housing to the plate 27.1. It is apparent that this construction enables adjusting the drill universally to dispose the axis of the chuck and/or the axis of the drill bit at any desired predetermined angle to the base and to the work on which the base rests.

The hook 51.1 and flat plate 27.1 are illustrative of only two possible forms of adapter for attaching a power drill to the coupling plate 51, it being considered as within the scope of the invention to design the configuration of the adapter plate according to the make of the power drill.

As previously related, the carriage 30 and the coupling plate 51 support the drill substantially centered between the

posts

22 and 24 and substantially centered with respect to the opposite sides of the base to insure stability. To provide for engaging the drill bit with the work on which the base is positioned the base is provided with an opening 20 (FIGS. 1 and 9) from the forward side of substantially rectangular configuration which extends from the front side to a place rearwardly of the axis of the drill bit and has spaced parallel inner sides 49-49 parallel to the sides and a transversely extending inner end 51.1 parallel to the ends of the base. This opening 20 provides the operator with a clear view of the work, of the locating lines on the workpiece and the gauge marks on the gauge plate and the mating of these to each other and in addition provides for the reception of a gauge plate 53 which is designed to enable aligning the axis of the drill bit with locating lines drawn on the workpiece marking the point thereon which is to be drilled. For receiving the gauge plate 53 the base has at its underside an upwardly extending recess 21 in which the gauge plate is mounted and secured by bolts 58. The gauge plate in one form, as shown in FIG. 4, comprises a flat plate 50 having along one side a straight edge and a deviating edge 64 beveled at 65. The straight edge 60 constitutes one gauge line and a mark 66 on the beveled edge on a line perpendicular to the straight edge 60 constitutes the other gauge line. The plate 50 contains spaced parallel slots 56-56 through which the screw bolts 5858 are inserted for attachment to the base and these slots are oversized so that the gauge plate can be adjusted forwardly and rearwardly, from side to side and angularly about a perpendicular axis.

The gauge plate may take other forms, as shown in FIGS. 5 and 6. For example, the gauge plate in FIG. 5

comprises a flat plate 52 having along one side a straight edge 60, deviating edges 72--72 and a hole 75. The straight edges 7272 intersect to form a point 73 which provides an index mark situated on a line perpendicular to the edge 60.

The gauge plate shown in FIG. 6 comprises a flat plate 54 having a straight edge 60, deviating edges 72-72 intersecting at a point 73, and a hole 75.

To enable adjusting the drill to dispose the axis of the chuck and/or bit at an angle perpendicular to the base, there is provided, as shown in FIGS. and 11, a jig 71 comprising a spindle 73 provided with a shank 75 at its upper end of such size as to fit into the drill chuck and at its lower end with a bearing surface 77. An arm 79 is connected at one end to the spindle 73 and has at its other end a leg 81 which is radially spaced from and parallel to the spindle and at its lower end a bearing surface 83 lying in the same plane as the surface 77. The spindle axis and the plane of the

surfaces

77 and 83 are at right angles. The power drill is fastened by means of the coupling to the carriage, the jig is mounted in the drill chuck and then the coupling is loosened whereupon the power drill is pushed down to engage the jig surfaces 77, 83 with the workpiece and then the jig is rotated through 180 about the axis of the spindle while maintaining the

surfaces

77, 83 continuously in contact with the work. As the jig is rotated the coupling is progressively tightened to maintain the power drill in the perpendicularity imposed by the jig until the finalized position is obtained whereupon the coupling is clamped tight to lock the power tool in place. When the drill has been fixed in its perpendicular position the gauge plate 53, shown in FIG. 4, may then be moved into engagement with the spindle 73 and fixed in place which will automatically align the intersection of the gauge marks 60 and 66 with the axis of the spindle 73 and hence of the drill bit when the latter is placed in the chuck. When using the guage plates shown in FIGS. 5 and 6 the gauge plate is moved to a position to permit the lower end of the spindle 73 to enter the hole 75 which automatically positions the gauge plate. To position the axis of the drill at angles other than perpendicular to the work a protractor may be employed.

At times especially for small workpieces it may be desirable to use the drill guide as a drill press and so there is provided a platen 76 (FIGS. 1, 2 and 3) which corresponds in configuration to the opening mounted in the opening by means of a hinge 78 recessed into the upper surface of the platen and the base so that the upper surface of the platen and base are uniformly flat. A ledge 49.1 along one side of the opening 20 and the forwardly extending portion of the base at the other side provide for supporting the platen at the desired level. The platen 76 can be tilted upwardly and rearwardly from the opening onto the surface of the base rearwardly thereof when the device is being used solely as a drill guide. When the device is to be used as a drill press the platen is tilted forwardly into the opening and to permit the drill to pass through the work an oversized hole 80 is provided in the platen through which the drill can pass. The platen may be removably mounted in the opening.

The

posts

22 and 24, as shown in FIGS. 1 and 2, are supported along one side of the base; however, it is within the scope of the invention to mount the posts at opposite sides of the base, as shown in FIG. 3, with the post 22 at the left front side and the post 24 at the right front side. When constructed in this fashion the opening 20 is situated between the posts.

There is optionally provided at the rear end of the base an opening or recess 82 of substantially rectangular configuration, across the open top of which is hinged a cover 84. This recess is designed to provide a receptacle for extra drill bits, a chuck key, pencils, and the like.

To prevent sliding of the base on the workpiece during the drilling operation friction pads 23 are secured to the lower side of the base at the four corners.

It should be understood that the: present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents falling within the scope of the appended claims.

I claim:

1. A portable drill guide comprising a base, a car riage, means mounting the carriage on the base for movement toward and from the: base,.said carriage being removable from said mounting means. a coupling mounted on the carriage for movement therewith to which a power drill together with a drill bit is adapted to be secured, and spring means yieldably supporting the carriage above the base for downward movement toward the base, said coupling being characterized in that it is adjustable on the carriage to dispose the drill in a predetermined position with the axis of the drill bit disposed in a predetermined angle to the base such that after said adjustment has been made the carriage may be removed from the mounting means to enable using the drill independently of the supporting base and replaced without having to make a readjustment to restore the drill to said predetermined position and predetermined angle.

2. Apparatus according to claim 1, wherein the carriage and coupling is adapted to be attached to the drill housing in a position such as not to interfere with the normal use of the drill when removed from the base.

3. A portable drill guide comprising a base, a post fixed to the base in an upright position, a carriage mounted on the post for movement thereon to and from the base, said carriage being removable from the post, a coupling mounted on the carriage for movement therewith to which a power drill together with a drill bit is adapted to be secured, and spring means disposed on the post between the base and the carriage for yieldably supporting the carriage above the base for downward movement toward the base, said coupling being charac terized in that it is adjustable on the carriage to dispose the drill in a predetermined position with the drill bit disposed at a predetermined angle to the base, and such that after said adjustment has been made the carriage may be removed from the post to enable using the drill independently of the base and replaced without having to make a readjustment to restore the drill to said predetermined position and angle.

4. Apparatus according to claim 3, comprising means for limiting upward movement of the carriage.

5. Apparatus according to claim 3, comprising means for limiting downward movement of the carriage.

6. Apparatus according to claim 3, comprising a second post fixed to the base in an upright position spaced forwardly and parallel to the first post and means on the carriage slidingly engaged with the second post.

7. Apparatus according to claim 6, wherein the second post is spaced forwardly of the axis of the drill bit.

8. Apparatus according to claim 6, wherein the coupling supports the drill substantially midway between the posts with respect to the front and rear ends of the base and substantially midway between the sides of the base.

9. Apparatus according to claim 3, comprising a second post fixed to the base in an upright position spaced transversely of and parallel to the first post, and means on the carriage slidingly engaged with the second post.

10. Apparatus according to claim 1, wherein the coupling comprises a universal joint.

11. Apparatus according to claim 1, characterized in that the coupling comprises a ball and socket joint.

12. Apparatus according to claim 1, wherein the carriage contains pairs of horizontally spaced smooth bore holes and pairs of vertically spaced threaded holes, and wherein two horizontally aligned screws extend through the smooth bored holes of the carriage and are threaded into the coupling and two vertically aligned screws are mounted in the threaded holes in the carriage above and below the horizontally aligned holes and abut the coupling.

13. Apparatus according to claim 5, wherein the carriage has vertically disposed, spaced parallel openings slidably engaged with the first post and a bifurcate slidably engaged with the second post.

14. Apparatus according to claim 6, wherein the first post is of circular cross-section and the second post is of non-circular cross-section and having screwthreaded portions for nut stops.

15. Apparatus according to claim 6, wherein the posts are fixed to the base along one side, the coupling supports the drill between the posts with respect to the front and back disposition of the drill and substantially midway between the sides with respect to the side-toside disposition of the drill and the base contains an opening below the bit which affords access of the bit to the work, a clear view of the locating lines on the workpiece and the gauge lines on the base.

16. Apparatus according to claim 15, wherein the opening extends rearwardly from the front end of the base to the rear side of the axis of the bit.

17. A portable drill guide comprising a base, a post fixed to the base in an upright position, a carriage mounted on the post for movement thereon to and from the base, a coupling mounted on the carriage for movement therewith to which a power drill together with a bit are adapted to be secured, said coupling supporting the drill forwardly and laterally of the post so as to be substantially centered on the base, and said coupling being adjustable to dispose the drill with the axis of the bit at a predetermined angle to the base, spring means on the post between the base and the carriage for yieldably supporting the carriage above the base, said base containing an opening below the bit which extends from the front of the base to behind the bit, and a gauge plate mounted on the base below the opening on which there are intersecting gauge lines.

18. A portable drill guide according to claim 17, wherein said gauge plate is adapted to be adjusted to align the intersection of said intersecting gauge lines with the axis of the bit.

19. Apparatus according to claim 17. wherein the gauge plate contains slots through which screw bolts are received and threaded into the base, and said slots are oversized so that the gauge plate is adjustable in a plane parallel to the plane of the base. forwardly and rearwardly, from side-to-side and angularly about a perpendicular axis.

20. Apparatus according to claim 17, wherein the gauge lines comprise edges of the gauge plate. one of which has on it a gauge mark situated on a line which intersects the edge of the other at right angles.

21. Apparatus according to claim 20, wherein the gauge marks and edges are located so as to extend to the bottom surface of the base adjacent the surface of the workpiece.

22. Apparatus according to claim 17, wherein a platen corresponding in configuration to the opening in the base is hingedly supported in the opening. in which position its surface is flush with the surface of the base. and for movement from said opening to a folded back position in which the surface rests on the base rearwardly away from the opening.

23. Apparatus according to claim 17, wherein a platen corresponding in configuration to the opening in the base is removably supported in the opening.

24. A drill guide according to claim 22, wherein the platen contains a clearance hole, the center of which is in substantial alignment with the vertical axis of the bit.

25. Apparatus according to claim 22, wherein there are shoulders along the inner opposite sides of said opening and the platen is adapted to rest on said shoulders when occupying said opening.

26. Apparatus according to claim 1, wherein there are traction pads secured to the underside of the base.

27. The combination with a drill guide according to claim 15, of an aligning device adapted to be inserted into the chuck of a drill, said aligning device comprising a post adapted to be lowered into engagement with the work and a radially extending arm extending from the post having an end coextensive with the lower end of the post, said device being rotatable in the chuck and by continuous engagement of the post and the extension with the work operable to dispose the drill with the axis of the chuck perpendicular to the work and as an aid to adjusting the gauge plate so that the gauge lines intersect the axis of the aligning device.

28. Apparatus according to claim 1, wherein the base contains a compartment provided with a hinged cover. l

Claims

1. A portable drill guide comprising a base, a carriage, means mounting the carRiage on the base for movement toward and from the base, said carriage being removable from said mounting means, a coupling mounted on the carriage for movement therewith to which a power drill together with a drill bit is adapted to be secured, and spring means yieldably supporting the carriage above the base for downward movement toward the base, said coupling being characterized in that it is adjustable on the carriage to dispose the drill in a predetermined position with the axis of the drill bit disposed in a predetermined angle to the base such that after said adjustment has been made the carriage may be removed from the mounting means to enable using the drill independently of the supporting base and replaced without having to make a readjustment to restore the drill to said predetermined position and predetermined angle.

3. A portable drill guide comprising a base, a post fixed to the base in an upright position, a carriage mounted on the post for movement thereon to and from the base, said carriage being removable from the post, a coupling mounted on the carriage for movement therewith to which a power drill together with a drill bit is adapted to be secured, and spring means disposed on the post between the base and the carriage for yieldably supporting the carriage above the base for downward movement toward the base, said coupling being characterized in that it is adjustable on the carriage to dispose the drill in a predetermined position with the drill bit disposed at a predetermined angle to the base, and such that after said adjustment has been made the carriage may be removed from the post to enable using the drill independently of the base and replaced without having to make a readjustment to restore the drill to said predetermined position and angle.

14. Apparatus according to claim 6, wherein the first post is of circular cross-section and the second post is of non-circular cross-section and having screw-threaded portions for nut stops.

15. Apparatus according to claim 6, wherein the posts are fixed to the base along one side, the coupling supports the drill between the posts with respect to the front and back disposition of the drill and substantially midway between the sides with respect to the side-to-side disposition of the drill and the base contains an opening below the bit which affords access of the bit to the work, a clear view of the locating lines on the workpiece and the gauge lines on the base.

19. Apparatus according to claim 17, wherein the gauge plate contains slots through which screw bolts are received and threaded into the base, and said slots are oversized so that the gauge plate is adjustable in a plane parallel to the plane of the base, forwardly and rearwardly, from side-to-side and angularly about a perpendicular axis.

20. Apparatus according to claim 17, wherein the gauge lines comprise edges of the gauge plate, one of which has on it a gauge mark situated on a line which intersects the edge of the other at right angles.

22. Apparatus according to claim 17, wherein a platen corresponding in configuration to the opening in the base is hingedly supported in the opening, in which position its surface is flush with the surface of the base, and for movement from said opening to a folded back position in which the surface rests on the base rearwardly away from the opening.

28. AppaRatus according to claim 1, wherein the base contains a compartment provided with a hinged cover.