Quinn, David Andrew (14 Hill View Court, Pilsdon Close Beaminster, Dorset DT8 3DF, GB)
Quinn, David Andrew (14 Hill View Court, Pilsdon Close Beaminster, Dorset DT8 3DF, GB)
| 1. | A drilling template for drilling holes along the centre line of a workpiece, the template comprising a bed for receiving a workpiece during drilling, a guide member having a plurality of through holes through which holes are drilled into the workpiece, a substantially vertical surface, and a slideable member on which the guide member rests, the centre lines of the through holes being substantially in the plane of the bed when the slideable member abuts the said vertical surface, sliding of the slideable member away from the said vertical surface serving to raise the centre lines of the holes relative to the bed. |
| 2. | A template according to claim 1, wherein sliding of the slideable member away from the vertical surface raises the guide member by substantially half the distance the slideable member is moved. |
| 3. | A template according to either of the preceding claims, wherein the guide member comprises a bar having through holes for guiding a drill bit during the drilling of holes in a workpiece. |
| 4. | A template according to any of the preceding claims, wherein the slideable member is substantially triangular. |
| 5. | A template according to any of the preceding claims, including means for securing the slideable member after it has been slid. |
| 6. | A template according to any of the preceding claims, including means for securing the guide member in a position to which it has been moved by movement of the slideable member. |
| 7. | A template according to any of the preceding claims, including a scale for setting movement of the slideable member. |
| 8. | A drilling template for drilling holes along the centre line of a workpiece, the template being substantially as herein described with reference to the accompanying drawings. |
One method of joining together planks of timber and the like 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 this 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 workpieces 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 faces of resin bonded particle boards, it is a particular problem when drilling into the thickness of the boards from the edges or ends 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 values, the use of a template which assumes a standard workpiece thickness will produce mis-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.
Furthermore, it cannot address the problems caused by different boards of a particular nominal thickness having different actual thicknesses.
According to the present invention there is provided a drilling template for drilling holes along the centre line of a workpiece, the template comprising a bed for receiving a workpiece during drilling, a guide member having a plurality of through holes through which holes are drilled into the workpiece, a substantially vertical surface, and a slideable member on which the guide member rests, the centre lines of the through holes being substantially in the plane of the bed when the slideable member abuts the said vertical surface, sliding of the slideable member away from the said vertical surface serving to raise the centre lines of the holes relative to the bed.
A template in accordance with the present invention will now be described with reference to the accompanying drawings in which:- Fig. 1 is a front view of the template during setting for a workpiece ; and Fig. 2 corresponds to Fig. 1 after the template has been set.
The illustrated template has a flat substantially horizontal bed 1, for receiving a board 2 which is to have holes drilled into its thickness, and two box section uprights 3 with a slot 11 therein, either of which can act as a datum line for the board 2. Two further box section members (not shown) are attached to the horizontal bed 1 and they extend horizontally and rearwardly from and in line with the uprights 3. These further box section members cooperate with the respective uprights 3 to define datum lines for the board 2.
A horizontal bar 4 has a plurality of evenly spaced holes 5 drilled therethrough and along its length. In use, the bar 4 also acts as a datum line for the board 2 when positioned against it. Knobs 10 on bolts which are slideable in the slot 11 in the uprights 3.
A front face 6 of the template 1 has a first triangular member 7 attached thereto on which can slide a second triangular member 8 which has a lip 9 which extends forward therefrom. In the position shown in broken lines in Fig. 1, the lip 9 of the triangular member 8 abuts the upright 3, and, with the bar 4 resting on the second triangular member 8, the centre lines of the holes 5 in the bar 4 are in line with the flat bed 1.
When holes are to be drilled in the board 2, the knobs 10 are loosened, and the board 2 is placed upright with its thickness between the left hand upright 3 and the lip 9, this necessitating sliding the second triangular member 8 in the direction of arrow A to the position shown in full line in Fig.
1 and lifting of the bar 4 to the position shown in Fig. 1. A wing nut or knurled knob 12 on a bolt threadably mounted in a vertical bar 13 attached to the first triangular member 7 is then turned to engage the second triangular member 8 and hold it in this position. The knobs 10 are then tightened to lock the bar 4 to the uprights 3.
The sides of the first and second triangles are such that the ratios of their horizontals to their uprights are both 2: 1, thereby resulting in the bar 4 being lifted by substantially exactly on half the distance the lip 9 has been moved by the board 2, that is half the thickness of the board 2.
As will be appreciated by those skilled in the art, the illustrated template enables holes to be drilled at substantially half way through the thickness of the board and without measuring the board thickness.
As can be seen from Fig. 2, sliding of the second triangular member 8 in the direction of arrow A also reveals a scale 14 which can be used to set the bar 4, for example when holes are to be drilled in the thickness of a workpiece at a position other than along its centre line. Due to the 2: 1 ratio of the horizontal to the vertical lengths of the triangular members 7 and 8, the scale 14 is itself magnified by a factor of 2: 1, thereby increasing the accuracy with which the second triangular member 8, and therefore the positioning of the centre lines of the holes 5, can be set.
In a preferred modification of the illustrated embodiment, the bar 4 is provided with two rows of through holes having centre lines which are in alignment with the bed 1 when the bar 4 is resting on the second triangular member 8 and the latter is positioned as shown by broken lines in Fig. 1. This can be achieved by reversing the bar 4 end to end between the uprights 3. The modification enables the bar 4 to be provided with holes of different diameters, for example 6 and 10mm, to enable holes of different diameters to be drilled in boards of different thicknesses. Furthermore, if the second row of holes is positioned in the bar 4 so that the centre lines of these holes are in the plane defined by the upper surfaces of the further box section members which extend rearwardly from the uprights 3, adjustment of the bar 4 using the second triangular member 8 as previously described will raise the bar 4 to the centre line of a workpiece when the latter is placed on top of the further box section members. This enables workpieces to be drilled which are wider than the distance between the two uprights 3 and their associated further box section members which extend rearwardly therefrom.
Although a horizontal to vertical ratio of 2: 1 is preferred for the triangular members 7 and 8, in that it enables holes to be drilled along the centre line of a board positioned between the upright 3 and the lip 9, other ratios could be used to position the holes 5 in the bar 4 at different positions relative to the thickness of the board. Such a change will also affect the scale magnification of the scale 14.