GB2386852A

GB2386852A - Adjustable drill jig

Info

Publication number: GB2386852A
Application number: GB0206647A
Authority: GB
Inventors: Susan Gillian Blessley; Andrew David Quinn
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-03-21
Filing date: 2002-03-21
Publication date: 2003-10-01
Anticipated expiration: 2022-03-21
Also published as: GB2386852B; AU2003215759A1; GB0206647D0; WO2003080278A1

Abstract

Apparatus for assisting the drilling of holes in workpieces to form joints between the workpieces using dowels, the apparatus comprising left and right hand vertical 3 and horizontal 5 guide means defining left and right hand vertical planes with which during drilling an edge of a workpiece can be abutted, and drill bit guide means 7 securable between the said left and right hand vertical 3 and horizontal 5 guide means, the drill bit guide means 7 having respective guide holes 8 therethrough positioned at substantially equal distances from said left and right hand vertical planes.

Description

- 1 Templates This invention concerns templates and more particularly

templates for accurately drilling holes in workpieces, for example for joining planks of timber and the like.

One method of joining planks of timber and the like together is to drill holes into the pieces to be joined and to insert dowels into the respective holes to join the pieces together. The two pieces are therefore butt jointed, with the joint reinforced with the dowels inserted into holes in both pieces.

As will be appreciated, in order to achieve accurate joining of the pieces it is necessary to have accurate positioning of the holes in them. Inaccuracies in drilling, and more particularly incorrect positioning of the holes in the respective pieces to be joined results in misalignment of the pieces when they are joined, and in some cases may even lead to the joint being impossible to make and/or damage to the pieces when attempts are made to form the joint.

The accurate drilling of holes required to facilitate the accurate joining of workplaces using dowels is a particular problem with wood, where the grain of the wood tends to throw the drill off the intended line, but it is even more of a

problem with resin bonded particle boards because such boards have an even more non-homogeneous structure than wood. Whilst the latter tends to be less of a problem when drilling into the thickness of resin bonded particle boards it is a particular problem when drilling into the thickness of the boards due to the alignment of the wood particles within the boards.

The above problems can be reduced substantially using drilling machines having a plurality of rigidly fixed drills which produce accurately aligned holes when the workpieces are correctly positioned in the machines. Such machines are used in the factory manufacture of furniture from chip board, coated for example with melamine or a veneer. However, such machines are very expensive and out of the reach of private individuals or small manufacturers.

Various proposals have, however, been made for overcoming the above problem, for example for the do-it-yourself market.

One such proposal is to use a drilling template which is clamped on to the edge of a board, the template having accurately positioned pre- drilled holes passing through it so that drilling through the holes into the workpiece produces holes in the workpiece which are accurately positioned relative to an edge of the workpiece. Different thicknesses of workpiece are accommodated for by the use of pre-drilled holes of different diameters in the template.

Such templates can enable holes to be accurately positioned so that the face of one board is flush with the end of the board to which it is joined. However, such templates do have problems, one being that whilst the various holes can be accurately positioned in one dimension, that is either within the thickness of one board and from an edge of the other, accurate positioning along the length of the joint which is to be formed is difficult. This can lead to the joined boards being out of alignment along the length of the joint. Furthermore, since the thickness of different workpieces can vary from specified

- 3 values, the use of a template which assumes a standard workpiece thickness will produce mix-aligned holes if it is not positioned consistently relative to one face of the workpiece or it will produce holes on the wrong alignment if it is oriented incorrectly relative to the workpiece.

A proposal for overcoming the problem of incorrect positioning of holes along the length of a joint is first to drill holes into the end of a board, for example using a template as described above, and then to insert into the holes-circular metal plugs having accurately positioned axial spikes. This board is then positioned as accurately as possible relative to the board to which is to be joined, and the spikes are pushed into the second board, thus marking the position for the holes to be drilled in the second board. Although this can provide some improvement in the accuracy of the resulting holes in the second board, it is often not that satisfactory due to the non-homogeneity of the second board itself. In other words, the drill can wander from its intended drilling position.

According to the present invention there is provided apparatus for assisting the drilling of holes in workpieces to form joints between the workpieces using dowels, the apparatus comprising left and right hand vertical and horizontal guide means defining left and right hand vertical planes with which during drilling an edge of a workpiece can be abutted, and drill bit guide means securable between the said left and right hand vertical and horizontal guide means, the drill bit guide means having respective guide holes therethrough positioned at substantially equal distances from said left and right hand vertical planes.

An embodiment of apparatus in accordance with the present invention will now be described with reference to the accompanying drawings in which: Fig. 1 is a perspective view of the embodiment; Fig. 2 is a view of the embodiment from the front;

Fig. 3 is a view of the embodiment from above; Fig. 4 is a view of the embodiment from one side; and Fig. 5 is a plan view of the embodiment set to drill holes producing a mitred joint.

As can be seen from Fig. 1, the illustrated apparatus has a horizontal bed 1 on to which workpieces are placed when they are being worked on, the bed 1 being connected to a vertical front face 2. The right angle formed between the horizontal bed 1 and the vertical front face 2 enables the device to be used over an edge of a workbench. The bed 1 can be a single flat sheet or, more preferably, in the form of a number of strips 27 which enable waste material to be removed more easily from the bed 1.

At each end of the vertical front face 2 are vertical rails 3 which are both of essentially box section with a vertical slot 4 extending along their respective lengths.

Extending along opposite edges of the horizontal bed 1 and away from the front face 2 are two horizontal rails 5 which are both of essentially box section with a horizontal slot 6 extending along their respective lengths perpendicular to the front face 2. The rails 5 both extend beyond the rear of the bed 1 for reasons which will become apparent.

Referring to Fig. 1, a bar 7 having holes 8 precision drilled therethrough along its centre line can be slid along the horizontal rails 5 and secured where desired using knurled knobs 9 on bolts (not shown) which pass through the slots 6 in the rails 5. Two locating blocks 10 are slideable in the horizontal rails 5 and can be secured thereto using knurled knobs 11 on bolts (not shown) which extend through the slots 6 in the rails 5. Projections 26 on the blocks 10 are such that with the bar 7 in contact with these blocks, the ends of the projections 26

- 5 - coincide with the centre line of the bar 7, that is also with the centre line of the holes S. Fig. 1 also shows a clamping bar 12 which can be slid along and secured to the horizontal rails 5, the bar being secured to the rails 5 using knurled knobs 13 on bolts (not shown) which pass through the slots 6. The underside of the bar 12 preferably has a strip of rubber adhered along its length, this serving to increase the clamping effect of the bar 12 when it is tightened down on to a workpiece.

Along the length of each horizontal rail 5 are scales 14 which can be used to set the position of the bar 7 accurately with respect to the front face 2 using the projections 26 on the blocks 10 as index markers relative to the scales 14.

As can be seen from Fig. 2, the bar 7 can also be secured to the vertical rails 3 using the knurled knobs 9 and their associated bolts by sliding the shanks of the latter into the vertical slots 4. However, instead of accurately positioning the bar 7 relative to the upper surface of the bed 1 using scales along the rails 3, a vernier scale 15 is provided on the front face 2, the scale 15 consisting of a first triangular portion 16 fixed -

to the front face 2, and a second triangular portion 17 which is slideable relative to the fixed portion 16. Suitable indicia 18 on the two triangular portions 16 and 17 enable the distance by which the slideable portion 17 is slid relative to the fixed portion 16 to give an accurate indication of the corresponding upward or downward vertical movement of the upper surface 19 of the slideable portion 17.

When the bar 7 is positioned as shown in Fig. 2, it can be slid up and down the rails 3 when the knurled knobs 9 have been unscrewed, for example by allowing the bar 7 to rest on the upper surface 19 of the slideable portion 17 of the vernier 15 and sliding the slideable portion 17 from side to side. Since the upper surface 19 of the slideable portion 17 of the vernier scale 15 is horizontal and parallel to the upper surface of the

- 6 bed 1, and the holes 8 have been drilled along the centre line of the bar 7, sliding of the slideable portion 17 relative to the fixed portion 16 results in the line of holes moving up or down and parallel to the upper surface of the bed 1. In addition, the vernier scale 15 indicates accurately the amount of such movement.

The holes 8 in the bar 7 are spaced equidistantly from each other, and the first and last of these holes are themselves positioned in the bar 7 so that they are both the same distance from the rails 5, and also from the rails 3.

The above described device can be used to produce accurately aligned holes for forming joints between two boards using dowels to effect the joints, and this will now be described in more detail. More particularly, a method of producing a rectangular framework, for example the carcass of a piece of furniture, will now be described. Four pieces of melamine coated chip board sheet, two of one length and two of another are used to produce the framework.

Before starting the hole drilling process, the bar 7 is removed from the rails 5. The first of one pair of boards is then placed on the bed 1 with one edge abutting the left hand rail 5, with the end of the board to be drilled abutting a front moveable stop 20 which has first been raised and secured in position using a knurled knob 21 threaded on a bolt (not shown) .

The clamping bar 12 is then positioned over the board and tightened down on to the board using the knurled knobs 13.

Slideable clamps 23 on the bar 12 are also slid along the bar 12 to abut the board and locked in position on the bar 12 using knurled knobs 24 to secure the board even more securely in position on the bed 1. The knob 21 is then unscrewed and the stop 20 is lowered.

The securing bolts for the bar 7 are then slid into the two vertical rails 3 until the bar 7 rests on the horizontal surface 19 of the vernier scale 15.

Depending on the actual as opposed to the nominal thickness of the board to be drilled, the slideable portion 17 of the vernier scale 15 is slid sideways to the right or to the left until the centres of the holes in the bar 7 are aligned with the centre line of the thickness of the board to be drilled. This can be effected, for example, by making the dimensions of the bar 7 and the positioning of the holes 8 therein such that when the centres of the holes 8 are aligned with the centre line of a board of a particular nominal thickness, the vernier scale 15 indicates zero. Movements of the slideable portion 17 from this zero position can then be shown on the scale 18 as positive or negative changes to the centre line of the holes 8 relative to its centred position for a board of nominal thickness. However,.

since this would also require the use of different blocks 10 if the overall dimensions of the different bars 7 were themselves different, it is preferred that the bars 7 are of substantially the same overall dimensions even if the holes 8 therein differ in size according to the desired size of hole to be drilled in the respective workpieces. The vernier scale 15 can then simply be calibrated to indicate relative movement of the slideable portion 17 relative to the fixed portion 16.

Knowing the actual thickness of the board to be drilled, the bar-

7 can be set using the vernier scale 15 so that the holes 8 are accurately positioned on the centre line of the board on the bed 1. Holes are then drilled into the end of the board on the bed 1 using an appropriately sized drill bit inserted into the desired number of holes 8 in the bar 7.

The clamping bar 12 is then released, and the board which has just been drilled is rotated end-on-end whilst keeping it in the same plane, and the board is then positioned against the right hand rail 5 and abutting a right hand stop 20' which has first been secured in its raised position using a knurled knob 21' on

a bolt (not shown). The clamping bar 12 is then clamped on to the board, and the stop 20' is lowered.

Since the bar 7 has already been set to produce holes on the centre line of the other end of the board, no adjustment of the bar 7 is required, and the required number of holes are then drilled into the end of the board through holes in the bar 7.

The second board of the same length can then have holes drilled into both of its ends, the bar 7 being kept in the position it was set for drilling holes in the first board.

The necessary holes in the end faces of the two other boards can then be produced as follows.

Two rear stops 25, 25' are raised and secured in position in a similar manner to that used for the two front stops 20 and 20'.

The clamping bar 12 is located in the tracks 5, followed by the bar 7.

The board which is to be provided with holes in its end face is then slid under the locating bar 12 and the bar 7 so that it is positioned with one edge abutting the left hand rail 5 and the stop 25. The sliders 23 are then slid along the locating bar 12 and secured in position, and the bar 12 is secured in position to fix the board on the bed 1.

The bar 7 and the blocks 10 are then inserted into the tracks 5 and the blocks 10 are secured to the tracks 5 using the knobs 11 so that the ends of the projections 26 on the blocks 10 are in the desired position for the centre line of the holes 8, this being such that the ends of both projections 26 are in register with the scale 14 at a distance which is half the thickness of the board. The bar 7 is then pushed into contact with the blocks 10 and it is secured in position using the knobs 9. The two scales 14 are set so that zero corresponds with the stop position of the two stops 25 and 25'. The desired number of

9 - holes are then drilled in the end face of the board by drilling through the holes 8 in the bar 7.

The board is removed from the bed 1 by releasing the clamping bar 12 whilst leaving the bar 7 in position, and it is rotated end-on-end whilst keeping it in the same plane. The board is then positioned against the right hand rail 5 abutting the stop 25' which has previously been raised. The clamping bar 12 is then tightened down on to the board, and the desired number of holes are drilled into the face of the board through the holes 8 in the bar 7 through the same holes 8 as were used to drill holes in the end of the board.

The second of the second pair of boards is then drilled in a similar manner to the first. As will be appreciated, two boards at a time can be placed in position for drilling, this having the advantage that forces on the various components of the apparatus can be substantially equilibrated between the left and right hand sides thereof.

All of the various holes are drilled in the boards using the rails 3 and 5 as datum lines which define left and right hand vertical planes with which the various workplaces are brought into registration before hole drilling is commenced.

Furthermore, the holes 8 in the bar 7 are accurately positioned relative to rails 3 and 5 and they start at the same distance from all of the rails 3 and 5. The result is that the holes drilled in the boards will be positioned so that when the four boards are joined using dowels inserted into these holes, the four boards will have edges which are substantially in the same plane set by the left and right hand vertical planes referred to above and not stepped as happens with mix-aligned holes. In addition, the holes in the boards are themselves accurately aligned, thereby aiding assembly of the various joints.

Finally, the accurate positioning of the holes on the centre line of the ends of the boards using the vernier scale 15 and the accurate positioning of the holes in the end faces of the boards using the index marks 26 with the scales 14 enables

particularly good alignment of the boards to be achieved along the length of the resulting joint.

Fig. 5 shows the embodiment of Figs. 1-4 being used to form a dowel reinforced mitre joint, the workpiece 30 having been pre-cut at an angle of 45 .

Instead of aligning an edge of the workpiece with the rails 5, the workpiece 30 is set on the bed 1 at an angle of 45 to the rails by abutting an edge of the workpiece 30 with a mitre guide 31 and the angled portion of the workpiece 30 abutting the stop 20' which is initially fixed in its raised position. The clamping bar 12 and the sliders 23 are then used to clamp the workpiece 30 in position on the bed 1, and the stop 20' is lowered. The bar 7 is then positioned in the vertical rails 3, in the desired horizontal alignment relative to the thickness of the workpiece 30, in a similar manner to that described in the production with right angled joints, and the desired number of holes are drilled into the workpiece 30 through the holes 8 in the bar 7.

Further holes can similarly be drilled in other appropriately cut workpieces to form completed mitre joints, and this preferably involves drilling holes in the ends of workplaces with the workpieces positioned against the left hand stop 20, thereby avoiding the necessity to turn the workplaces over when drilling opposite ends of an individual workpiece.

As will be appreciated, instead of the mitre guide 31, or preferably in addition, the bed 1 can be provided with lines to indicate correct positioning of workpieces when mitre joints are being formed. It will also be appreciated that joints at angles other than 90 or 45 can be formed using the device, for example using appropriate lines on the bed 1 and/or using an appropriate guide secured to the rails 5.

In a modification of the above described embodiment, the bar 7 has stepped end portions where the steps are of a depth equal to the external dimensions of the square sectioned rails 3. When these modified bars are secured to the rails 3 they provide a surface which can replace the front stops 20 and 20'. In addition, their greater thickness can serve to provide greater accuracy of drilling through the holes 8 due to the increased depth of the latter.

In another modification of the above described embodiment the bar 7 can be provided with two adjacent rows of holes 8 along its length, the holes in one row being of a different diameter from those in the other, for example 8mm in one row and lOmm in the other. This avoids the need for more than one bar 7 if holes of different diameters are to be drilled in workpieces.

When the bar 7 has two rows of holes of different diameters, the centre lines of the respective rows are preferably at substantially equal distances from the edge of the bar 7.

Although holes 8 of different diameters could be set at different pitches along the length of the bars 7, whether in the same bar or different bars, it is generally preferred that they are all set to the same pitch irrespective of hole diameter.

This avoids positioning problems for the holes 8 bearing in mind that it is important to be able to drill holes in both end and face of workpieces which are at the same distance relative to the left and right hand vertical planes defined by the rails 3 and 5.

The illustrated embodiment has been particularly described with reference to drilling holes at precise positions in a single workpiece. However, it is generally preferred to locate two workpieces in the device at the same time and to drill the required holes in both with both clamped on the bed 1 as this reduces the risk of distortion of the device which might occur if only one workpiece is clamped on the bed 1. This is, of course, not practicable when drilling holes as illustrated with reference to Fig. 5.

Claims

- 12 Claims

1. Apparatus for assisting the drilling of holes in workpieces to form joints between the workplaces using dowels, the apparatus comprising left and right hand vertical and horizontal guide means defining left and right hand vertical planes with which during drilling an edge of a workpiece can be abutted, and drill bit guide means securable between the said left and right hand vertical and horizontal guide means, the drill bit guide means having respective guide holes therethrough positioned at substantially equal distances from said left and right hand vertical planes.

2. Apparatus according to claim 1, wherein the left and right hand vertical and horizontal guide means comprise vertical and horizontal rails to which the drill bit guide means is securable.

3. Apparatus according to claim 2, wherein the drill bit guide means can be secured to both the horizontal and vertical rails.

4. Apparatus according to any of the preceding claims, including vernier adjustment means for adjusting the drill bit guide means in a vertical plane perpendicular to said left and right hand vertical planes.

5. Apparatus according to any of the preceding claims, including securing means for securing workpieces in abutment with said left and right hand horizontal guide means whilst holes are drilled therein using the drill bit guide means.

6. Apparatus according to any of the preceding claims, wherein the drill bit guide means has a plurality of guide holes therethrough in a single row, the guide holes all being of the same diameter.

7. Apparatus according to any of claims 1 to 5, wherein the drill bit guide means has a plurality of guide holes

- 13 therethrough in a plurality of rows, the guide holes in each row all being of the same diameter.

8. Apparatus according to any of claims 1 to 5, wherein the drill bit guide means has a plurality of guide holes therethrough in one or more rows, the guide holes in each row or rows being of different diameters from others in the same row.

9. Apparatus according to any of the preceding claims, including a mitre guide which in use abuts either the left or right hand horizontal guide means whereby holes can be drilled in a workpiece to form a doweled mitre joint.

10. Apparatus for assisting the drilling of holes in workpLeces to form joints between the workpieces using dowels, the --

apparatus being substantially as herein described with reference to the accompanying drawings.