GB2113282A

GB2113282A - Wood preservation

Info

Publication number: GB2113282A
Application number: GB08232061A
Authority: GB
Inventors: Ian Malcolm Robertson
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-12-24
Filing date: 1982-11-10
Publication date: 1983-08-03
Also published as: GB2113282B

Abstract

In order to be able to treat wood such as a window frame periodically with a preservative, a longitudinally extending cavity is formed within the wood into which the preservative can be introduced. In one embodiment the cavity is formed by cutting a channel in the wood and partially filling it with a filler strip so as to define an internal cavity (see Figs. 1 to 5). In another embodiment, the internal cavity is formed by a plurality of intersecting bores 120 (see Figs. 8, 9 and 10). There is described apparatus for forming the channel and apparatus for use in forming the intersecting bores.

Description

SPECIFICATION Wood preservation The present invention relates to a method of treating wood with a preservative, to a wood member adapted to be treated by the method and to apparatus for use in adapting the wood member for treatment.

Wood is usually treated with a preservative prior to use to prevent or inhibit rot or decay of the wood. The wood may be dipped, brushed, pressure injected or otherwise impregnated with the preservative. Where the wood is used in the building industry, for example for window frames, door frames or the like, it is usually sealed by the application of paint to the externally exposed surface. The paint acts to prevent ingress of water and the like whose presence would increase the likelihood of wood decay. Once painted, further treatment of the wood with wood preservative has not heretofore been readily possible.

However, the presence of the paint does not totally eradicate the possibility of water ingress and hence rot and decay is still possible. For example, water may penetrate the wood in the region of corner joints where the surface finish may be broken, or by way of adjacent brick work.

Thus it would be desirable to treat wood periodically after installation without recourse to removal of the external paint surface.

Treatment of window frames and the like, e.g.

remedial treatment, after installation is known but the treatment is restricted to localised areas, for example around corner joints, and requires holes to be bored into the wood, where the wood preservative is injected, and subsequent plugging of the holes after injection. Clearly, there is no possibility of periodic re-treatment without the redrilling and the consequent further disturbance of decor on each occasion.

An object of the present invention is to combat the likelihood of decay from the commencement of installation, and to enable wood to be periodically treated with wood preservative without continually disturbing the external surface coating, and to render the requirement for external painting of the frame as a means of protection against decay totally unnecessary.

According to one aspect of the invention there is provided a method of treating wood with a preservative, comprising introducing by way of a closeable orifice, wood preservative into a continuously extending cavity disposed within the wood to be treated.

Preferably the wood to be treated is in the form of a frame, for example a window or door frame, each part of the frame having an internally disposed cavity, which cavities are in communication with one another.

The method has the advantage that the preservative is absorbed into the wood and spreads outwardly from the respective internal cavities thus protecting the wood without continually disturbing any exterior coating present on the wood.

According to another aspect of the present invention there is provided a method of treating wood with a wood preservative in which a closed channel or cavity is formed within the wood and into which is introduced the preservative by way of a closeable orifice.

In one embodiment the closed channel is formed by cutting a channel into the wood and inserting a filler piece so as to preferably lie flush with the surface of the wood into which the channel is cut, whilst leaving an internal space which defines the closed channel.

In another embodiment, a plurality of bores are drilled at angles along the length of the wood to be treated, such that adjacent bores intersect to thereby define the cavity within the wood when the bore openings are closed off.

Both methods of treatment are ideally suited for wood which has an external finish such as paint since it enables the wood to be treated with preservative, having once formed the internal channel, without disturbing the external coating.

The method is particularly suitable for treating window frames, door frames or the like, when in situ and is also applicable to the treatment of structural frameworks. In the case of a framework, each part of the frame may be provided with a closed channel, with each of the closed channels interconnected in such a way that the minimum number of injection orifices are required. The injection orifice may be disposed in any convenient member and a vent port disposed at the highest point in the interconnecting channels. This would facilitate the refilling process insomuch that it could be performed thereafter by the occupant utilising a simple gravity feed method if so desired.

The insert may be wood or plastics material and is preferably glued in position.

According to another aspect of the present invention there is provided an apparatus for forming channels in wood when in situ comprising a guide bar adapted for location relative to the wood to be channelled, a saddle moveable longitudinally on said guide bar, and a router for forming the channel in the wood and carried by the saddle.

Preferably the router is positioned adjustably with respect to the saddle.

In one embodiment the router is mounted to the saddle by means of a sleeve which has left and right hand threads at respective ends for respective threading engagement with the saddle and a nut member of the router whereby the router may be adjusted transversely with respect to the saddle. Once adjusted as desired the position may be fixed by the use of lock nuts. With one or other of the lock nuts released the router may be moveable angularly.

Preferably the nut is slidable on a pair of guide rails whereby the vertical position of the router may be adjusted. A vernier screw device may be provided for adjustment purposes. Locking means may be provided to lock the router in the required position.

According to another aspect of the invention there is provided a length of timber or a timber frame having a longitudinally extending cavity therein, and a closeable passageway extending between an external surface of the timber and the cavity.

Preferably the timber has a longitudinally extending insert which fits in a longitudinal channel, which insert extends only partially into the channel to define the said cavity.

In another embodiment the cavity is formed by a plurality of angled bores which intersect with adjacent bores. The bore openings are closed off by suitable plugs. The closeable passageway comprises a one-way ball valve to prevent any fluid introduced into the channel by way of the valve from escaping.

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which~ Fig. 1 is a simplified perspective view of a window frame incorporating channels according to one aspect of the present invention; Fig. 2 is a cross-section on 11-Il of Fig. 3; Fig. 3 is a perspective view of part of a window frame in accordance with the invention; Fig. 4 is an end view of one embodiment of a filler strip; Fig. 5 is a section through a frame member of another embodiment showing one possible location of a filler hole; Fig. 6 is an end view showing apparatus for forming channels in a position for channelling the window sill; Fig. 7 is an exploded perspective view of the apparatus of Fig. 6;; Fig. 8 is a perspective view of part of a window frame showing the location of interconnecting bore holes forming a channel in the frame; Fig. 9 is a perspective view of part of a window-frame showing the location of bore holes according to another embodiment of the invention; Fig. 10 is a section through a timber member showing one arrangement for forming and plugging the bore holes; Fig. 11 is a perspective view of a jig for use in forming the indented bore holes; Fig. 12 is an end view of the apparatus of Fig.

11 partially in section; and Fig. 13 is a perspective view of part of a casement window frame according to another embodiment of the invention.

Referring to the drawings, there is shown a wooden window frame 1 having two vertical bars 3 interconnected by horizontal top and bottom bars 5. The frame is divided into four by an intermediate vertical bar 7 and a horizontal bar 9 which intersect at 11. The bottom bar 5 forms a sill. Each of the bars 3, 5, 7 and 9 have therein a longitudinally extending cavity or closed channel 15 indicated by dotted lines in Fig. 1. The channels 15 are interconnected by various means described further hereinafter. A closeable orifice 17 in communication with the channel 15 is provided at any convenient location in the frame.

A bleed port 18 may be provided in the channel 15 at the highest point thereof. The arrangement is such that wood preservative may be injected into the closed channel 15 by way of the closeable orifice 17 so as to fill the interconnecting channels 15 and penetrate the wood. The wood preservative is preferably injected under pressure at say, 100 p.s.i. The closeable orifice 17 is formed by a non-return ball valve which is screwed into a threaded hole (say 10 mm diameter), formed in the timber. The preservative is adsorbed in a direction from the inside out. Thus periodic treatment can be carried out without disturbing any external coating on the wood.

Preferably, the closed channel 15 is formed by cutting a longitudinally extending channel 20 into the wood and then inserting a filler strip 19 which is shallower than the depth of the channel so that when fitted flush with the surface it defines the closed channel 15 (see Figs. 2 to 5). The filler strip as illustrated in Fig. 4 has been designed with a system of protruding barbs on either side of the strip. This provision permits the strip to be both wedged and glued firmly within the channel thereby rendering it capable of sustaining the injection period at 100 p.s.i.

The channel 20 may be machined perpendicularly into the timber or as illustrated in Fig. 2 at 200 to the perpendicular. This is done when any masonry or cement rendering surrounding the frame prevents the router cutter used to form the channel from striking the appropriate place on the frame. It will be seen that the channel 20 is extended in depth by drilling holes 23 periodically along the length of the channel.

It will be seen that the channels 20 formed in the members 3, 5, 7 of the frame are not continuous in the embodiment illustrated. The breaks 21 are to avoid obstructions such as hinges 22 and the screw fixings. Where no such obstructions exist the channelling 20 can be continuous. Fig. 3 illustrates in greater detail a part of the frame in the region of such a break.

The channels 20a, 20b are interconnected by inclined bores 24, 25 which extend from the respective channels to an intersection point 26. A jig may be employed, as described further hereinafter, to ensure accurate alignment of the bores. In the illustration, a hole 27 is bored in the wood substantially perpendicularly, or at an angle of 200 to the perpendicular as appropriate to intersect at point 26. The bore serves as a filler orifice 17 and accommodates a non-return ball valve.

Referring to Fig. 4 it will be seen that the exterior face of the filler strip 1 9 is chamfered at an angle of 200 so that it would lie flush with the surface of the wood when inserted in an angled channel 20. The closed channel or cavity 15 is generally rectangular in cross-section and is located at a prescribed and optimum depth concealed below the outer surface of the timber.

The size is consistent with the overall dimensions of the particular member. As shown, the insert is finished flush with the outer surface of the timber and the outer surface may in practice be coated with an external finish such as paint. The size of the channels is preferably chosen so as to contain just sufficient preservative to give effective treatment.

Fig. 5 shows an alternative arrangement where the closeable orifice 17 is formed in a different face of the timber to the channel 20. This arrangement is to be preferred when for example the channel 15 is formed in the timber when new.

Thus the surface of the timber having the insert 19 may be placed up to the adjacent partitioning or block walling with the orifice 17 being on one of the visible and accessible sides of the timber.

It is envisaged that the interconnecting closed channels 15 are formed in the frame in situ although the frames may well be supplied from new with the channel-ways already formed therein. Thus the channel-ways may be formed in the bars forming the window frame during manufacture.

Referring to Figs. 6 and 7 there is shown apparatus for forming channels in wood. The apparatus is designed for use in situ and comprises a guide bar 25 which is T-shaped and which is adapted to be fixed relative to the wood to be channelled. For example, in the case of a window frame it may be fastened between the horizontal bars 5 when machining the vertical bars 3 and between the vertical bars 3 when machining the horizontal bars 5. A saddle 27 is longitudinally slidably guided on the T-shaped guide bar 25 whilst being permitted only minimal play in the transverse direction.

In the preferred embodiment illustrated, the side edges of the head of the T-bar 25 are chamfered. A pair of longitudinally spaced wheels or bearings 28 engage with each side edge and two pairs of wheels or bearings 30 engage with the head. The axles carrying the wheels or bearings 30 may be spring biased so as to take up any free play. Each end of the T-bar 25 is mounted to the frame by way of a swivel block 32 which is mounted for angular movement on a mounting block 34. Each mounting block 34 can be secured directly to members of the frame or where a sill is to be channeled by way of a clamping bracket 36 (see Fig. 6). The mounting block 34 has abutment surfaces 39 which enable the swivel block and hence the T-bar, to be angled at 200 on either side of the perpendicular.

A portable die grinder or equivalent machine 29 capable of driving a router cutter 31 is carried by the saddle 27. The die grinder is secured to a mounting plate 33 by means of a bracket 35, and a pair of parallel bars 37 are secured to the plate 33. A nut member 41 is slidable on the bars 37 and a threaded shaft 38 rotated by means of a wheel 42 serves to adjust the position of the mounting plate 33 and hence the machine 29.

Means are provided for locking the nut member and hence the router in the selected position.

A spindle 47 connects the nut member 41 to a radius arm 48 which is in turn secured to the saddle block by a clamping arrangement 50 comprising a headed bolt 52 and a locking wheel 54. The radius arm has a slot therein through which passes the spindle of headed bolt 52. The locking wheel 54 co-operates with the threaded end of the bolt 52 and engages the side of the saddle 27 remote from the radius arm whereby the radius arm may be clamped in any desired position on the saddle 27. By this means the basic depth of cut for the router can be set or the angle of the router adjusted. The angle of the router may also be adjusted by means of locking nut 51.

Where it is required to inject wood preservative into a timber structure such as a window frame, door frame or the like, which already has the internal channel-ways, the liquid is introduced from a commercial dispenser and delivered under minimum pressure or controlled pressure via a non-return valve of the dispenser and an adapter and nozzle which connects with the orifice 17 in the timber. The orifice has a threaded portion for connection with the nozzle of the dispenser.

Alternatively, the nozzle may be received in the orifice as a tapered fit. The liquid is injected so as to fill to capacity all the inter-connecting channels beneath the surface of the timber frame. The applicator is then removed thus leaving the injected fluid concealed within the timber members where it will, in due course, permeate through and across the grain of the entire frame.

Further fluid may be injected at convenient intervals thus ensuring the preservation of the timber for a lengthy and indefinite period.

Where a timber frame already in situ is required to be treated with preservative and it is not provided with the internal channel-ways the apparatus described above is employed in the following manner to cut channels in the timber members constituting the frame. By way of example the method will be described for the channelling of the upper horizontal bar 5 of the window-frame 1 illustrated in Figure 1. The guide bar is first secured to the vertical frame members 3 approximately at the correct distance from the horizontal bar 5 and parallel thereto, that is to say at a distance at which the router 31 is in the centre of the bar 5.Where the frame is recessed in from the surface of a wall the guide bar may be of a width to fit in the recess or alternatively blocks may be provided which fit between the guide bar 25 and the frame members 3 so that the guide bar is positioned clear of the wall. The saddle 27 carrying the motor 29 with router cutter 31 is then positioned on the guide bar 25.

The height of the router 31 normal to the wood surface of the timber frame is then adjusted by sliding the motor 29 with respect to the nut member 41 by rotating the threaded shaft 38.

This may be done with the motor running and the depth may be gradually increased. The cutter may be run along the length of the timber to be channelled several times with the depth of cut being increased on successive runs until the required depth is reached. The router cutter may be moved angularly whilst running to remove the debris from the channel, the normal position corresponding with the depth of the channel. The cutter is then moved longitudinally whilst guided on the guide bar thus forming a longitudinally extending open channel of a predetermined depth in the horizontal member 5. The process is repeated for the other vertical horizontal bars 3, 5, 7, 9, constituting the frame 1. The channelling can be interrupted to avoid an obstruction.

Preferably the guide bar 25 is secured to the frame by screws which lie in the line of the channel so that no screw holes are visible after completion of machining. When it is required to machine a channel in the sill the brackets 36 are employed to secure the guide bar 25 in position.

The bracket 36 is held fast and in position by means of four adjustable bolts 81. All bolts are tightened sufficiently to allow a firm grip to be obtained without placing any undue strain likely to be detrimental to the timber. The finished surface of the wooden sill is protected from damage by the bolts by the incorporation of a large flat plate washer 83.

Where there is a possibility of excessive seepage via ill fitting joints caused by incorrect manufacture or consequent warping or shrinkage of timber it may be desirable to isolate the corner joints from the channel. Thus, the channel would terminate adjacent the corner joint in which case the cavity formed by the channel and filler would not be a continuous cavity round the entire frame.

Clearly it can be seen that if undue seepage of fluid via ill fitting joints or misplaced nail holes, or knot holes etc., etc., did occur, then the specific and offending section could be isolated, thus receiving its quota of preservative fluid on a strictly controlled basis.

Preferably the channels in each member are arranged to connect with one another at the joints between the bars making up the frame.

Alternatively, but less preferably, separate channels for each member of the frame may be provided. Interconnecting passages are cut between the channel in the sill and the channel in the vertical members of the frame. Preferably, one is cut at either end so avoiding dead ends and possible air locks.

The channel is preferably approximately 4 mm wide and 18 mm deep. Having cut all the necessary channels, inserts in the form of extruded plastic are cut to the required length, coated with glue on their sides and pushed into the channel until flush with the outer surface of the timber. The inserts are approximately 5.5 mm wide and 12.5 mm deep.

When the channels have been cut by the router cutter and prior to filling of the indents, a 4 mm, round drill may be applied to bore continuation holes into the timber members. Such holes will provide for deeper penetration of preservative across the grain of the timber when placed at approximately 150 mm centres. The holes further improve the performance of the invention because they penetrate both the heartwood and the sapwood. Since the liquid preservative is not absorbed quite so readily by the heartwood, it ensures that the heartwood cannot in itself form a barrer which would prevent the preservative from gaining access to the far side of the timber member. The continuation holes are drilled through the base of the existing channel and terminate at 1 5 mm from the far side of the timber member as detailed in Figs. 2 and 3.

When it is required to inject wood preservative into a timber structure such as a window frame, door frame or the like, which already has the internal channel-ways, the liquid is introduced from a commercial dispenser and delivered under controlled pressure via a non-return valve of the dispenser and via a pressure chamber into the channel of the frame until pressure is seen to build up. At that point air from the compressor is introduced at 100 p.s.i. and maintained for a period of three minutes or until traces of preservative are seen to be exuding from the frame. The multi nozzle connectors which fit into the orifice 17 in the timber have a threaded portion for connection with the nozzles of the pressure chamber. Alternatively, on a different model a single nozzle may be received into the orifice as a tapered fit. The liquid is injected so as to fill to capacity.

The pressure chamber is capable of receiving liquid preservative from a suitable dispenser (Tecalamit oil pump) via a non-return valve and then distributing the liquid via a single or multi nozzle outlets into the timber frame. It follows that more than one frame member can be filled at one time.

The pressure chamber consists of a cube of heavy gauge steel which is capable of withstanding the pressures required. It has various component parts attached to it comprising: (i) a pressure gauge zero to 150 p.s.i.

(ii) an air vent (iii) inlet 1/4 B.S.P. complete with non-return valve to accept liquid preservative from the dispenser.

(iv) inlet 1/4 B.S.P. complete with non-return valve to accommodate air from a compressor.

(v) multi nozzle outlets all uniform in size presently 1/4 inch B.S.P.

(vi) all nozzle outlets and inlets have their own independent stop cock valve attached.

The chamber need only hold a fairly small reserve of liquid, 200 cc being satisfactory, since the dispenser is capable of pumping sufficient liquid through the pressure chamber directly to the fame members. When the frame has taken its immediate fill of liquid the balance fills the pressure chamber to capacity until a small pressure begins to register on the pressure gauge.

At this point the air is introduced from the compressor at 100 p.s.i. and held for about three minutes or until liquid is seen to exude from the joints. At this stage the appropriate stop cocks are turned off and the apparatus removed from its connection to the frame member, and a blanking plug preferably made of nylon bearing its own 10 mm thread is screwed into the aperture or filler hole. As an alternative a ball bearing non-return valve may be employed as the filler/blanking plug combined. However, this is less preferable on account of the valve protruding from the timber member, which would not be particularly acceptable to following tradesmen e.g. window cleaners etc.The bores can be formed at any convenient angle and the overlap between adjacent bores can be varied to suit particular circumstances, provided that as a general rule they intersect at about 18 mm below the outer surface of the member, and terminate at about 1 5 mm from the rear face. These distances will accommodate the pressure in question for the period in question and ensure that the timber is adequately supplied with preservative.

Typically the bores are 6.4 mm in diameter and the filler holes 10 mm threaded. Only one filler hole is needed per section and a vent hole would be optional, but would however be relevant if subsequent "fillings" were carried out under gravity feed.

A suitable preservative is a solution of pentachlorophenol 5% in white spirit (high grade).

Insecticides such as those known by the trade names Lindane or Dieldrin may be added to the preservative. A water-repellent may also be incorporated.

Since the frame to be treated with preservative may contain both heart wood and sap wood in the case of the former invention which proposes a channel cut into the surrounding surface of the timber member, it is proposed to make extended drillings at spaced intervals along the channel.

This is to ensure that the wood preservative has direct access to the sap wood. Thus, where the channel is machined in heart wood, the drillings, which may be perpendicular or inclined, penetrate further into the wood increasing the chance of penetrating the sap wood. The holes may be at 6" centres and inclined at 300. In the case of the second embodiment of the invention which proposes to form the continuous channel within the timber member by using a multiplicity of cross bores, it will be appreciated that extended drillings will not be necessary and therefore do not apply.

Advantageously the first treatment with wood preservative may be preceded by treatment with a wetting agent which acts to increase permeability of the wood preservative. The final treatment may be followed by treatment with a water repellent.

The treatment may be carried out under pressure to increase penetration.

The method has the advantage over any existing treatments that topping up is possible at intervals until the desired saturation is achieved; the whole length of the frame is protected; there is virtually no loss due to evaporation; and leaching out of the minerals is not possible.

In an alternative embodiment, illustrated in Figs. 8, 9 and 10, the need for a filler strip is avoided. The continuously extending cavity is formed by a plurality of bores 120 which are drilled into the wood at an angle, so that adjacent bores intersect. Part of a frame is shown in Fig. 8 with the interconnecting bores shown by the dotted lines. The bores 120 are drilled from any convenient face of the wood frame, and each bore hole 122 is filled with a plug 124 which is preferably glued in position. A hot melt adhesive may be employed. In a preferred arrangement shown in Fig. 10 two plugs are employed. A first plug 124 is inserted into the bore hole 122 and a second bore 125 drilled perpendicularly to the face of the timber receives a second plug 126.

Glue is introduced behind the plug 124, and the second plug is finished flush with the surface of the wood. The second plug is approximately 12 mm in length and cut across the grain.

The bores 120 of adjacent members of the frame are arranged to connect where the members 3 and 5 are joined together so that a frame can be treated from one filler point 128.

The filler point is connected to the bores 120 by way of a bore 129 provided with a filler adapter.

Alternatively, one of the openings 122 of the bores 120 may be fitted with the filler adapter.

The adapter can comprise a nipple which can be screwed into the wood to align with the bore 128. A tube or other connecting means may be fitted to the nipple to permit preservative to be introduced into the cavity from a suitable applicator. This may be done under a pressure of up to 100 p.s.i. as previously described. In one embodiment, once the cavities have been filled, and where necessary, the fluid allowed to penetrate into the wood under pressure, the filler adapter is removed and a threaded blanking plug 130 screwed in position in place of it. The blanking plug is preferably a plastic, such as nylon. As an alternative a spring-loaded nonreturn valve may be employed as the filler adapter and blanking plug.

The bores 120 can be formed at any convenient angle and the overlap between adjacent bores can be varied. The more the adjacent bores overlap then the better the treatment of wood, since more holes would be required for a given length of wood. The adjacent bores may be commenced from the same surface bore, i.e. without overlap, but this is a less preferred arrangement as the resulting surface opening is more difficult to plug.

Typically the bores 120 are 6 mm diameter and the filler hole 128, 10 mm diameter. Only one filler hole is needed and a vent hole is not necessary when the preservative is injected under pressure.

After the channels, i.e. bores, 120 have been drilled they are preferably cleaned out using compressed air. With the bore openings 122 blocked off, the system can be tested for leaks etc using air pressure.

Figs. 11 and 12 show apparatus for forming the inclined bores 120 in the framework. The apparatus comprises an L-shaped bar 132, preferably having an included angle of 85", which is adapted to be secured either directly or by mounting brackets in a position so that the bar is parallel with that member of the frame to be drilled, with preferably one arm 134 resting on that member. Both arms 134, 136 of the Lshaped bar have a slot 138, 140 therein running substantially the whole length of the bar. A selection of bars of different lengths are provided.

The bar is adapted to have mounted thereon a drilling jig which comprises a disc-shaped guide member 142 which is rotatable on a spindle 144.

The spindle has a conical head portion 146 which mates with a conical portion of a bore formed in the guide member. The spindle passes through the slot 140 in the arm 136 of the L-shaped bar and has a threaded end with which a nut member 148 engages. The guide member has therein a cordal bore 150 whose angle of inclination relative to the wood member to be drilled is adjusted by rotation of the guide member. The guide member is located in the desired position along the bar by rotating the nut 148 to clamp the guide member in contact with the arms 136 of the L-shaped bar. A side plate 152 is carried fixedly by the spindle and serves as an abutment for a locating pin 1 54 which is used in selecting the desired angle of the guide member.The guide member has a plurality of circumferentially spaced axially directed holes 156 disposed therein, corresponding in number to a number of preferred angles for the holes. Each of the holes is positioned such that the locating pin can only be inserted into one hole at any one time with the locating pin contacting the upper edge of arm 136. Thus, this mechanism serves to set the guide member at the desired angle. The guide member may then be clamped in position as previously described.

Once the preferred angle of inclination of the holes and the depth to which they are to be drilled has been decided, the number of holes required in a given length of timber can be calculated, whereupon successive holes are drilled in the wood at the determined spacings by passing a drill through the cordal bore 150 and into the wood, repositioning the jig on the bar as appropriate. Adjacent holes are bored at alternating angles of inclination so that they intersect and the angle of the jig may be adjusted appropriately for each hole. For convenience, the drilling jig may have two cordal bores disposed at 900 to one another.

After drilling of the inclined bores, the surface openings are blanked off using plugs as previously described, leaving one bore hole connecting with the plurality of intersecting inclined bores which serves as the closeable orifice by way of which the wood preservative is introduced into the cavity extending around the framework. The embodiment of Fig. 9 illustrates an alternative in which the bore holes 122 stop short of the joints, i.e. the cavity formed in, for example, the top member 5, does not interconnect with the cavity formed in the side member 3. This solution is adopted when the joint between the members 3, 5 is loose and where leakage would occur at the joints if all the members were connected together.

Fig. 13 illustrates an arrangement enabling opening windows to be periodically treated with wood preservative. The timber from which such frames are made has a relatively small crosssection which makes channelling by the previous method unsuitable. The solution adopted is to drill a longitudinal bore down the centre line of the specific member or at a point when it will be equidistant from the periphery of the timber. In order to carry out this operation it is necessary to remove the window casement from its hinges which attach it to the main frame. Preferably, the casement is placed exterior face downwards on to a jig where it is clamped firmly in position to allow the drilling of the longitudinal bores to take place.

A bore 1 60 is drilled in each of the members which constitute one corner of the casement. The casement is then removed from the clamps and turned into position to allow the second corner to be drilled, and so on, until all four corners are complete. It has been found preferable to utilize a drill of 500 mm in length whose diameter is approximately 6 mm. The outer section of the bores are plugged with a short section of dowel plug 162, timber or plastics or metal material of round section is acceptable. It is then followed up with a hot melt glue immediately behind the plug to ensure a total seal is obtained.

The filler hole 166 is then drilled from any convenient edge of the casement ensuring that it traverses the channel bore 160 which has previously been formed.

It will be appreciated that in situations when window casements possess overall dimensions of 800 nm or less, it is possible to drill a longitudinal concealed channel round the entire section of the casement. However, in situations where one or both of these dimensions is exceeded the corner sections are drilled longitudinally to the fullest depth permitted by the drill, with the centre sections, which are least susceptible to decay, either omitted, or drilled at intervals across the grain and filled independently as considered necessary. When the bores have been drilled and plugged the filler adapter is introduced into the orifice provided on the edge of the casement and it is then pressurised with liquid preservative in similar manner to the main frame. The adapter is then removed and a threaded plug preferably of nylon material is screwed into the filler orifice until flush with the timber. The casement is then replaced on its hinges in the original position. It will be observed that no trace of drillings can be observed from either the interior or the exterior faces of the casement. The filler hole, threaded nylon bung, could be observed when the window was in the open position.

As an alternative the casement can be immersed in a sealed tank and pressure treated.

Claims

1. A method of treating wood with a preservative comprising forming a cavity or a closed channel extending longitudinally within the wood and introducing a preservative into the closed channel or cavity by way of a closeable orifice.

2. A method as claimed in claim 1, in which the cavity within the wood is formed by drilling a plurality of bores into the wood, which bores are angled so that adjacent bores intersect, and blanking off the surface openings of the plurality of bores with the exception of at least the closeable orifice.

3. A method as claimed in claim 1, in which the closed channel is formed by cutting a channel into the wood and inserting a filler piece into the channel to leave an internal space defining the closed channel.

4. A method as claimed in any preceding claim, in which the closeable orifice is adapted to receive either a blanking plug or a filler adapter.

5. A method as claimed in any preceding claim, in which the wood to be treated is in the form of a frame.

6. A wooden frame formed by a plurality of members, a cavity or closed channel extending longitudinally within each member and a respective closeable orifice for introducing a wood preservative into the or each closed channel or cavity.

7. A wooden frame as claimed in claim 6, in which the closed channel or cavity in one member is in communication with the closed channel or cavity of another member.

8. A wooden frame as claimed in claim 6 or 7, in which the closeable orifice is adapted to receive a filler adapter or a filler plug and a filler adapter incorporating a non-return valve.

9. A wooden frame as claimed in any of claims 6, 7 or 8, in which the cavity in each member is formed by a plurality of angled bores, and in which adjacent bores intersect with one another.

10. A wooden frame as claimed in any of claims 6, 7 or 8 in which the closed channel is formed by fitting a longitudinal filler piece into a longitudinal channel formed in the member.

1 1. Apparatus for forming a longitudinal channel in a wooden member comprising a guide bar adapted to be secured to the wooden member to be channelled or to another member secured thereto, a saddle mounted for longitudinal movement on the guide bar, and a rotatable cutter carried by the saddle.

12. Apparatus as claimed in claim 1 in which the rotatable cutter is mounted for movement perpendicularly to the direction of longitudinal movement of the saddle.

13. Apparatus as claimed in claim 12, in which a fine and coarse perpendicular movement is provided, the fine adjustment being provided by a vernier screw arrangement interposed between the cutter and a radius arm connected to the saddle, and the coarse adjustment being provided by a slotted connection by means of which the radius arm is secured to the saddle.

14. Apparatus as claimed in claim 13, in which the slotted connection allows the cutter to be moved angularly with respect to the saddle in a plane parallel to the direction of longitudinal movement of the saddle.

15. Apparatus as claimed in any of claims 11 to 14, in which the guide bar is secured to the wooden member by way of a swivel block which allows the guide bar to be offset from the perpendicular with respect to a face of the member to be channelled.

16. Apparatus as claimed in claim 15 in which the guide bar has an offset angle of 200 either side of the perpendicular.

17. Apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings of Figs. 6 and 7.

18. Apparatus for use in boring one or more holes in wood at inclined angles comprising a guide bar adapted to be secured to the wood in which the holes are to be bored, a guide member which has therein at least one cordal bore and which is mounted to be movable longitudinally along said guide bar, the guide member being rotatable and means being provided for locating the cordal bore in the guide member at a desired angle.

19. Apparatus as claimed in claim 18 in which the guide bar is L-shaped having an included angle between the limbs of 850 and one of the limbs having therein a slot which extends substantially the whole length of the bar, and in which a spindle is received slidably therein, on which spindle the guide member is arranged for rotation.

20. Apparatus as claimed in claim 18 or 19, in which a plurality of circumferentially spaced holes are disposed in the guide member and a locating pin is received in a selected one of the holes and co-operable with an abutment surface to locate the guide member in a selected angular position.

21. Apparatus constructed and arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings of Figs. 1 1 and 12.

22. A method of treating wood substantially as hereinbefore described, with reference to the accompanying drawings.

23. A wooden frame constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.