WO1993016818A1

WO1993016818A1 - Method and apparatus for drilling into fibrous materials, whereby dust is extracted and the surface of the bore is sealed

Info

Publication number: WO1993016818A1
Application number: PCT/GB1993/000336
Authority: WO
Inventors: Keith David Dungate
Original assignee: Keith David Dungate
Priority date: 1992-02-19
Filing date: 1993-02-18
Publication date: 1993-09-02
Also published as: GB9203655D0; AU3508893A

Abstract

For forming a through bore through a board (2) of asbestos, two plates (4) of plastics material are adhered on opposite surfaces thereof. Apertures (6) in the plates (4) are aligned. A respective container (8) is supported on each plate (4) such that each container opening (14) surrounds the plate (4). The interior of each container (8) is connected to a respective vacuum cleaner (16) by way of a hose (18). With the vacuum cleaners (16) switched on a drill (24) is extended through one of the containers (8), and through the aperture (6) in the respective plate (4) into the board (2) and drilling is commenced. Material removed from the board (2) by the drilling enters the containers (8) and is extracted to the vacuum cleaners (16) in which it is collected. Once drilling is complete, the bore (28) produced may have its surface sealed or lined.

Description

METHOD AND APPARATUS FOR DRILLING INTO FIBROUS MATERIALS, WHEREBY DUST IS EXTRACTED AND THE SURFACE OF THE BORE IS SEALED

The present invention relates to methods and apparatus for drilling material.

Currently, because of the hazards involved, it is not allowed to drill into a fibrous material such as asbestos. Accordingly, if contractors find asbestos during construction works, the whole works have to be stopped whilst the asbestos is removed in an approved manner. This of course not only delays projects but is very costly.

Frequently it is only required to run cables, pipes or other services through the part of the construction containing the asbestos or to attach fixings thereto, and it is only the prohibition against drilling the asbestos which necessitates its removal. There are no structural or safety reasons why the asbestos cannot be retained in place if a safe method of drilling the asbestos as required can be found.

It is an object of the present invention to provide a method for drilling into material, for example as asbestos, which is safe and practical.

According to a first aspect of the present invention there is provided a method for drilling a bore or recess, the method comprising the steps of supporting a container such that an opening thereof surrounds an area of material to be drilled, and drilling into said area to form a bore or recess by drill means arranged to extend through said container, the arrangement being such that material removed by the drill means is received in the interior of said container, and connecting the interior of said container to extraction means for extracting said removed material from the container interior, and the method further comprising the step of lining or sealing the surface of the bore or recess formed by said drill means.

With an embodiment of a method of the invention, drilling into material, for example, into asbestos, is safe because the fibres and dust products removed by the drilling are extracted by way of the container by the extraction means. The removed material produced by the drilling does not therefore enter the atmosphere. Furthermore, once the drilling is completed, the newly drilled surface is lined or sealed so that no fibres or dust can escape therefrom.

In an embodiment, the newly formed surface of the drilled bore or recess is lined or sealed by spraying the surface with a lining or sealing material. This may be, for example, a plastics material such as PVC. Clearly, the lining or sealing material must be able to prevent fibres or dust escaping from the newly drilled surface.

Additionally and/or ^"alternatively, the drilled bore or recess is lined with a lining or sealing material, for example, a plastics material. This lining or sealing material may be fixed to the bore or recess in any suitable manner, for example by mechanical fixing means and/or by adhesive. or bonding.

It would be possible for the material to be drilled by using the drill means first to drill into and through the container, and then to drill into the material. However, in a preferred embodiment, the container is provided with a bore through which the drill means may extend into and through the interior of the container to said area to be drilled. Said bore is arranged in said container in alignment with the opening thereof. The bore in the container is preferably arranged to provide guidance to said drill means during a drilling operation.

For safety it is important that all of the material removed by the drill means is received in the interior of the container. In this respect, a plate is preferably supported at the area to be drilled such :hat the opening of the container abuts the plate. Prefe »Ωly, the plate is provided with at least one aperture arraiv.ϊ.d to be aligneu with the bore or recess to be formed. During drilling, the aperture in the plate will act to guide the drill means.

The invention also extends to apparatus for drilling a bore or recess by the method defined above.

The present invention also extends to an apparatus for drilling a bore or recess, said apparatus comprising a container having an opening therein which is arranged to surround the bore or recess during drilling, an extraction hose having a first end communicating with the interior of the container, and an extraction unit connected to a second end of said extraction hose, and further comprising drill means arranged to extend in the interior of the container and project through said opening therein.

Such apparatus may be arranged as a portable unit, for example, to facilitate sampling of unknown materials in situ.

Where the apparatus is to be used for sampling, it preferably further comprises a perforated sample plate mounted within the interior of said container to extend across said the first end of said extraction hose.

In an embodiment, the apparatus further comprises sealing means associated with _tsaid container opening. The sealing means may comprise a flexible sealing ring extending around said container opening. Additionally and/or alternatively, said sealing means comprises a plate having at least one aperture therein, the container opening being arranged to abut said plate such that the aperture in the plate communicates by way of the opening with the interior of the container.

According to a further aspect of the present invention there is provided apparatus for drilling a bore or recess, said apparatus comprising a plate having at least one aperture therein, a container having an opening which is arranged to abut said plate such that the aperture in the plate communicates by way of the opening with the interior of the container, drill means arranged to extend in the interior of the container, through the opening therein and into said aperture in the plate, and an extraction aperture in said container in communication with the interior thereof for connection to extraction means.

The plate is preferably arranged to be fixed to the material to be drilled. Obviously, the plate may be fixed in position by any suitable.means. For example, it might be hung or taped in position. In a particularly preferred embodiment, the plate is to remain on the material after the drilling has been completed. Generally, it is preferred that the plate should be adhered, or bonded to the material. The shape of the plate and the number of apertures therein will be chosen in dependence upon the particular application.

Where the plate is securely fixed to the material to be drilled, for example by adhesive or other fixing means, it may be arranged to support the container in position.

For example, the container may be provided with engaging or fixing means arranged to engage the plate. The engaging means may comprise suction clamps, clips or the like. In this case, the opening of the container may be arranged to surround the plate, and the engaging or fixing means may be arranged to engage the material to be drilled.

Alternatively, the container opening may be arranged to abut the surface of said plate such that the engaging or fixing means engage with the plate.

Preferably, the container is provided with a bore for the passage of the drill means therethrough, which bore is aligned with at least one aperture of the plate when the container opening is in abutment with the plate. The or each bore for the drill means may be provided with appropriate sealing means to seal the bore when no drill is in place and/or to seal around the drill means as it extends through the bore.

The interior of the container is arranged to be connected to an extraction unit by way of a hose sealingly engaged with the container interior.

In a preferred embodiment, said extraction unit is a vacuum cleaner.

The. invention also extends to a method for drilling a bore or a recess utilising apparatus as defined above.

The invention also extends to a method for drilling a bore through a layer of material, the method comprising the steps of supporting a respective container at each of two opposed surfaces of said layer such that openings of said containers are aligned, and drilling a bore through said layer in alignment with said container openings, said bore being drilled by drill means extending through the interior of one of the containers into said layer, the arrangement being such that material remoyed by the drill means is received in the interior of one or both of the containers, and connecting the interior of each of the two containers to extraction means for extracting said removed material from the container interiors.

The method defined above enables the drilling of a through bore through a layer of material, with the removed material being extracted from the drilling site by the extraction means. The layer of material may, of course, be any material, but the method is particularly useful for drilling fibrous or dust making materials, for example as asbestos, which can be hazardous.

Common extraction means may be connected to the interiors of the two containers. However, preferably, an individual extraction means communicates with the interior of each container. In most circumstances, both extraction means would be operated for the whole of the drilling operation, but, particularly where the layer of material is thick, the extraction means communicating with the container remote from the drilling operation may be operated after the drilling operation has commenced.

In a preferred embodiment, the surface of the through bore foimed by drilling is lined or sealed. The lining or sealing of the surface is to prevent the escape of dust or fibres from the formed surface. For example, the surface may be sprayed with a suitable material. The material may be a bonding agent or may be a sealing agent. In a preferred embodiment the surface is sprayed by a plastics material, for example, PVC.

Additionally and/or alternatively, a tube may be extended within the drilled bore such that the inner surface of the tube forms a bore, for example, for the passage of cables, pipes or other services. The tube may be of any required material, but in a preferred embodiment, said tube is made of a plastics material.

In a presently preferred embodiment, a respective plate is fixed to each of the two opposed surfaces of said layer of material before the drilling operation is commenced. Each said plate may be provided with at least one aperture therein and the apertures in the respective plates are aligned. The bore drilled through said layer is drilled to be in alignment with the aligned apertures of said plates. These apertures in the plates therefore act to guide the .drill means during the drilling operation.

In a preferred embodiment, the plates are fixed to the opposed surfaces of said layer of material by adhesive or bonding material.

Where a tube is inserted in the drilled bore, it is preferred that the tube extends into the apertures of said two plates. Preferably, a respective part of the exterior of the tube is fixed to each plate. For example, an end of the tube may be fixed to the aperture of the respective plate. The tube may be fixed to each plate by any suitable means, for example by mechanical fixing means, by adhesive or by bonding.

In a presently preferred embodiment each of said plates is of a plastics material and said tube is also^' of a plastics material. This enables a plastics seal to be formed between the tube and each said plate. For example, the tube and the plates may be heat sealed or bonded together.

The present invention also extends to apparatus for performing the method defined above. Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows an exploded perspective view of apparatus of the invention for providing a through bore through a board of asbestos,

Figure 2 shows a section through an asbestos board showing a completed through bore,

Figure 3 shows an exploded perspective view of a further embodiment of apparatus of the invention for drilling a bore through a panel of material, and

Figure 4 shows a section through a panel of material showing a fixing in position thereon.

The present invention is described hereinbelow with reference to the provision of through bores in panels or boards of asbestos. However, it will be appreciated that this invention can be used to make bores or recesses in any material. The invention is particularly useful when it is required to drill fibrous or dust making materials, and particularly for drilling materials such as asbestos which are subject to statutory controls. Furthermore, whilst a through bore would commonly be drilled in a panel of the material, it will be appreciated that the invention is also useful for drilling material in bulk, or indeed in any other form.

Figure 1 shows an exploded perspective view of apparatus of the invention in position for forming a through bore through a board 2 of asbestos. In this respect, two plates 4 of plastics material are adhered on opposite surfaces of the board 2 so that they are substantially in alignment. Each plate 4 is provided with an aperture 6 therethrough and these apertures 6 are aligned. Furthermore, the aligned apertures 6 define the position in which the bore is to be drilled. Although in the embodiment illustrated it has been specified that the plates 4 are made of a plastics material, it will be appreciated that they may be made of any other suitable material, for example of metal or wood. The material chosen will generally depend upon the size and the application. For example, metal plates are particularly useful where it is required to minimise fire hazards in the completed construction.

When the plates 4 have been affixed in the appropriate position, a respective container 8 is supported thereon. In the embodiment illustrated, each container 8 is substantially cuboid in shape and formed by a base wall 10 from which four upstanding side walls 12 extend. The free edges of each side wall 12 together define a container opening 14. -In the embodiment illustrated, each opening 14 is arranged to surround the respective plate 4 substantially in abutment with the edges thereof. In this manner, each plate 4 effectively forms a front wall for the respective container 8 and seals the container. The aperture 6 is therefore in communication only with the interior of the container 8.

Each container 8 may be fixed to the board 2 and/or to the respective plate 4 during the drilling operation.

Alternatively, the workman performing the drilling may hold the container 8 in position. In this case, the plate 4 will help to maintain the container 8 in the correct position.

Each container 8 is also connected to a respective vacuum cleaner 16 by way of a hose 18 which is arranged to extend through one of the side walls 12 to communicate with the interior of the associated container 8. The connection between the hose 18 and the side wall 12 through which it extends is arranged to be sealed. It will be appreciated that operation of each vacuum_ιcleaner 16 will extract any material from the interior of the respective container 8 into the associated vacuum cleaner 16. To facilitate the operation of the vacuum cleaners 16, one of the containers 8 is provided with an air inlet 20, which, in the illustrated embodiments, is in a side wall 12 thereof. Preferably, the air inlet 20 is provided with a one-way valve, and may be provided with air filter means.

The vacuum cleaners 16 may be of any suitable type, or other extraction means may be provided to remove the material from the interiors of the containers 8^'. However, the extraction means employed need to have associated means, such as bags or canisters, to contain the removed material.

One of the two containers 8 is provided with a hole 22 in its base wall 10 which is substantially the same size as,- and is aligned with, the aperture 6 in the respective plate 4. The hole 22 and the aperture 6 act as guide means for a drill, schematically indicated at 24. In this respect, the drill 24 is positioned to extend into the respective container 8 through the hole 22^' provided and to extend through the aperture 6 to enable it to drill through the board 2.

The drill 24 may be of any suitable construction. However, it is preferred that the drill 24 be a core drill so that the material is removed as a core.

It will be appreciated that once the two containers 8 have been supported in position, with their openings 14 surrounding the plates 4, the drilling operation can be commenced- As a preliminary of the drilling operation, the vacuum cleaners 16 are switched on, and then the drill 24 is extended through the respective container 8 into contact with the board 2 by way of the aperture 6. Drilling is then undertaken substantially as conventionally. The material removed from the board 2 by the drilling enters into the containers 8 and is extracted by the vacuum cleaners 16 and collected in the bags or containers (not shown) provided. Thus, any dust or fibres formed by tne drilling operation are extracted and collected. At the finish of the drilling operation, the drill 24 is removed, but the containers 8 are retained in position. Generally, the vacuum cleaners 16 are kept switched on for some little while after the finish of drilling to ensure that all free and loose material is extracted. At this sτage the vacuum cleaners can be switched off and a sealant is sprayed through the bore which has been produced. The sealant may be sprayed through the container 8. Alternatively, one or • both of the containers 8 may be removed and the sealant sprayed through the bore by way of one of the plates 4. The sealant, which, for example may be PVC, is arranged to seal the newly formed drilled surface to prevent the escape of dust or fibres therefrom.

In the embodiment illustrated, the drilled bore 28 is to be utilised for the passage of service cables or pipes. Accordingly, a tube 26 is passed through the completed bore 28 as indicated in Figure 2. The tube 26 may be of any suitable. material, but is preferably of a plastics material, for example, of PVC. In the embodiment illustrated, the plates 4 are retained on the opposed surfaces of the board 2 such that the tube 26 extends through the apertures 6 therein. Clips 30 are used to clip the tube 26 to the plates 4 and hence retain the tube in position. However, if required, the external surface of the tube 26 may be adhered or bonded to each of the plates 4. For example, this might be done by a heat sealing operation, particularly if the plates 4 and the tube 26 are made of the same material. It will be immediately apparent from Figure 2 that the tube 26 defines a duct through which services may be passed. This duct is perfectly safe to use as it is insulated from the material of the board 2.

In Figure 2, the tube 26 protrudes from the surface of each plate 4. Of course, if required, once in position the tube 26 may be cut or formed so that the ends thereof are substantially flush with the plates 4.

In the embodiment illustrated, the containers 8 are cuboid in shape. However, these containers may, of course, be of any suitable shape. In an alternative embodiment, each said container is in the form of a hollow cylinder of substantially circular cross-section having a substantially circular container opening at one end thereof for cooperation with a substantially circular plate, as 6. The base of the container spaced from its circular opening will also be circular, in this embodiment, and preferably contains an aperture for the insertion of a drill or other tool. The hose 18 communicating with the interior of the container 8 may be coupled through the peripheral wall of the cylindrical container or through its base.

Figure 3 shows a further embodiment of apparatus of the invention illustrating how more than one bore may be provided in the same panel or board. In this respect, in Figures 3 and 4 parts which are the same or similar to those of Figures 1 and 2 have been given the same reference numerals.

It will be seen from Figure 3 that each plate 4 is provided with more than one aperture 6. A respective bore may be drilled in the board 2 through each said aperture 6, and in this respect, the base wall 10 of one of the containers 8 is provided with a respective drill hole 22 aligned with each said aperture 6. However, to maintain the container 8 sealed during drilling, an air seal, indicated at 32, is provided in each hole 22. The air seal 32 is arranged to enable passage of the drill 24 but to seal the hole 22 when no drill is extending therethrough.

Each container 8 is, in the embodiment shown in Figure 3, provided with opposed pairs of suction fixing clamps 34. These fixing clamps are fixed to two opposed side walls 12 of each said container 8, and are arranged to clamp against the board 2 adjacent to the side edges of the plate 4.

Figure 4 shows the use of the drilled bore 28 to retain a fixing. Again, the plates 4 have been retained on opposed surfaces of the board 2 and after the bore 28 has been completed its inner surface is sprayed as described above. A bolt fixing 36 is then inserted through one of the plates 4 into the bore 28 through an air seal washer 38. The engaging means 40 for the bolt fixing 36 is inserted through the opposed plate 4 and also maintains a respective air seal washer 38 in position around the respective aperture 6. Thus, the ends of the bore 28 are sealed by the respective plate 4 and the respective air seal washer 38 such that no dust or fibres can escape. It will be appreciated that the bolt fixing 36 may be used to carry a secondary fixing indicated at 42.

In the embodiments illustrated, the apparatus is shown when used to facilitate the drilling of through bores in a panel. However, apparatus of the invention is also extremely useful for forming recesses or closed bores in panels or in other material.

Of course, where there is no intention to drill through the material it is not necessary to provide the second container or vacuum cleaner. In this respect, only a single container, as 8, with its associated vacuum cleaner 16 is required.

It is frequently necessary to assess the composition of a construction, for example, to ascertain if asbestos or other dust forming materials are present. Apparatus of the invention enables this to be done particularly easily. The person making the analysis takes apparatus of the invention comprising a container, as 8, and a coupled vacuum cleaner, as 16, to the site to be investigated. In this instance, it may not be necessary to use a plate as 4, but it should be ensured that the opening of the container 8 is sealingly in contact with the material to be sampled. An endless sealing ring (not shown) may, for example, be provided around the periphery of the container opening 14.

For sampling purposes, a perforated sample plate such as a sheet of gauze, indicated at 50 in Figure 3, is mounted within the container over the inlet for the hose 18. The sample plate 50 thus extends across the open end of the hose 18. A support flange (not shown) for the sample plate 50 may be formed in the container inlet in which the end of the hose 18 is secured.

In use, the container 8 is pressed against the materia . to be sampled so that its opening 14 is sealingly in contact therewith, and the vacuum cleaner 16 is switched on. Thereafter, a small sample of the material is drilled by way of the drill 24 in conventional manner. Most of the material will be sucked into the vacuum cleaner 16 but a pad thereof can be built up on the gauze or other perforated sample plate 50. The resultant pad is generally sufficient for analysis purposes.

The apparatus, when it is to be used for sampling can be arranged to be portable to facilitate its use in situ. For example, the vacuum cleaner may be strapped to the person.

Apparatus as described above, whether using a single container 8, or two cooperating ones, can also be used, for example, when wet stripping fluid pipes or other structures coated with asbestos or dust forming material. In this instance it is generally necessary to make a small bore through the coating material to the inner pipe or support so that a stripping fluid can be forced through the bore to soak between the outer coat and the inner structure. A stand alone version of apparatus of the invention, perhaps with a appropriately shaped container or container opening, is extremely useful for such applications.

It will be appreciated that variations in and modifications to the embodiments described and illustrated may be made within the scope of the present invention.

Claims

1. A method for drilling a bore or recess, the method comprising the steps of supporting a container such that an opening thereof surrounds an area of material to be drilled, and drilling into said area to form a bore or recess by drill means arranged to extend through said container, the arrangement being such that material removed by the drill means is received in the interior of said container, and connecting the interior of said container to extraction means for extracting said removed material from the container interior, and the method further comprising the step of lining or sealing the surface of the bore or recess formed by said drill means.

2. A method as claimed in Claim 1, wherein the newly formed surface of the drilled bore or recess is lined or sealed by spraying the surface with a lining or sealing material.

3. A method as claimed in Claim 2, wherein said sprayed material is a plastics material.

4. A method as claimed in any preceding claim, wherein the drilled bore or recess is lined with a lining or sealing material.

5. A method as claimed in Claim 4, wherein said lining or sealing material is a plastics material.

6. A method as claimed in Claim 4 or 5, wherein the lining or sealing material is fixed to the bore or recess by mechanical fixing means.

7. A method as claimed in any of Claims 4 to 6^', wherein the lining or sealing material is fixed to the bore or recess by adhesive or bonding,

8. A method as claimed in any preceding claim, wherein said container is provided with a bore through which the drill means may extend into and through the interior of the container to said area to be drilled.

9. A method as claimed in Claim 8, wherein the bore in the container is arranged to provide guidance to said drill means during a drilling operation.

10. A method as claimed in any preceding claim, further comprising the step of supporting a plate at the area to be drilled such that the opening of the container abuts the plate.

11. A method as claimed in Claim 10, wherein said plate is provided with at least one aperture, and further comprising aligning said aperture with the bore or recess to be formed.

12. Apparatus for drilling a bore or recess by the method defined above.

13. Apparatus for drilling a bore or recess, said apparatus comprising a container having an opening therein which is arranged to surround the bore or recess during drilling, an extraction hose having a first end communicating with the interior of the container, and an extraction unit connected to a second end of said extraction hose, and further comprising drill means arranged to extend in the interior of the container and project through said opening therein.

14. Apparatus as claimed in Claim 13, further comprising a perforated sample plate mounted within the interior of said container to extend across said the first end of said extraction hose.

15. Apparatus as claimed in Claim 13 or 14, further comprising sealing means associated with said container opening.

16. Apparatus as claimed in Claim 15, wherein said sealing means comprises a plate having at least one aperture therein, the container opening being arranged to abut said plate such that the aperture in the plate communicates by way of the opening with the interior of the container.

17 Apparatus for drilling a bore or recess, said apparatus comprising a plate having at least one aperture therein, a container having an opening which is arranged to abut said plate such that the aperture in the plate communicates by way of the opening with the interior of the container, drill means arranged to extend in the interior of the container, through the opening therein and into said aperture in the plate, and an extraction aperture in said container in communication with the interior thereof for connection to extraction means.

18. Apparatus as claimed in Claim 16 or 17, wherein said plate is. arranged to be fixed to the material to be drilled.

19. Apparatus as claimed in any of Claims 16 to 18, further comprising engaging or fixing means provided on said container and arranged to engage the plate.

20. Apparatus as claimed in any of Claims 13 to 19, wherein said container is provided with a bore for the passage of drill means therethrough.

21. Apparatus as claimed in Claim 20, further comprising sealing means for the or each bore for the drill means and arranged to seal the respective bore when no drill means extends therethrough and/or to seal around the drill means as it extends through the bore.

22. Apparatus as claimed in Claim 17, wherein the interior of the container is arranged to be connected to an extraction unit by way of a hose sealingly engaged with the container interior.

23. Apparatus as claimed in any of Claims 13 to 16 or 22, wherein said extraction unit is a vacuum cleaner.

24. A method for drilling a bore or a recess using apparatus as claimed in any of Claims 13 to 23.

25. A method for drilling a bore through a layer of material, the method comprising the steps of supporting a respective container at each of two opposed surfaces of said layer such that openings of said containers are aligned, and drilling a bore through said layer in alignment with said container openings, said bore being drilled by drill means extending through the interior of one of the containers into said layer, the arrangement being such that material removed by the drill means is received in the interior of one or both of the containers, and connecting the interior of each of the two containers to extraction means for extracting said removed material from the container interiors.

26. A method as claimed in Claim 25, wherein an individual extraction means communicates with the interior of each container, and further comprising the step of operating at least one of the extraction means before the drilling operation is commenced.

27. A method as claimed in Claim 25 or 26, further comprising lining or sealing the surface of the through bore which has been formed by the drilling.

28. A method as claimed in Claim 27, wherein a sealing agent is sprayed onto the drilled surface to line or seal the through bore.

29. A method as claimed in Claim 27 or 28, further comprising the step of positioning a tube to extend within the drilled bore such that the inner surface of the tube forms a bore.

30. A method as claimed in any of Claims 25 to 29, further comprising the steps of fixing a respective plate to each of the two opposed surfaces of said layer of material before the drilling operation is commenced, each of said plates being provided with at least one aperture therein and the apertures in the respective plates being aligned, and then drilling the bore such that the bore extends through said layer in alignment with the aligned apertures of said plates.

31. A method as claimed in Claim 30, wherein said plates are fixed to the opposed surfaces of said layer of material by adhesive or bonding material.

32. A method as claimed in Claim 30 or 31, further comprising the step of positioning a tube to extend within the drilled bore such that the inner surface of the tube forms a bore, the tube extending into the apertures of said two plates.

33. A method as claimed in Claim 32, wherein a respective part of the exterior of said tube is fixed to each said plate.

34. Apparatus lor performing,a method as claimed in any of Claims 25 to 33.

35. A container for use in an apparatus or method as claimed in any preceding claim.

36. A method for drilling a bore or recess, substantially as hereinbefore described with reference to the accompanying drawings.

37. Apparatus for drilling a bore or recess, substantially as hereinbefore described with reference to the accompanying drawings.