GB2411371A

GB2411371A - A drill bit and plug

Info

Publication number: GB2411371A
Application number: GB0427925A
Authority: GB
Inventors: David Smith
Original assignee: STORYCLOSE Ltd
Current assignee: STORYCLOSE Ltd
Priority date: 2004-02-28
Filing date: 2004-12-21
Publication date: 2005-08-31
Also published as: GB0404474D0; GB2411370A; GB0427925D0

Abstract

The invention relates to a drill bit 10. The drill bit 10 comprises a body 16, being of generally truncated cone shape, and the periphery of which has three blades 18 arranged thereon. The invention also relates to a corresponding plug 30 and a method of shaping a hole in a partition of a building, so as to produce a bore of generally truncated cone shape.

Description

-

241 1 371

A DRILL BIT AND A PLUG

The present invention relates to a drill bit and a plug.

In particular, the drill bit is for use on a hand held, manual or electrically powered, drill.

The drill bit is designed to shape an existing hole in a partition (for example, a wall, a floor or a ceiling) of a building. The plug can then be placed in the shaped hole in the partition so as to make good the partition.

Currently, when electricians, plumbers and any other persons require access to subfloor areas or wall cavities, gaining such access is time consuming, typically involving the lifting up of floorboards, the cutting of chipboard floor boards, which often necessitates removing lots of furniture / carpets. The floor then has to be repaired which can be costly and in the case of shipboard, difficult to do to a satisfactory standard. Gaining access to plasterboard wall cavities is difficult to achieve without destroying fairly large portions of the plasterboard. The plasterboard then has to be repaired, probably replastered and redecorated, which can be time consuming and expensive..

It is known to use a router to cut a hole in a partition. Such methods are fairly complicated, typically requiring a template attached to the partition, and then the router must be moved circularly across the material to make a hole in the partition.

An aim of the invention is to provide a simpler method of making holes in partitions.

According to a first aspect of the invention there is provided a drill bit comprising a body, the body comprising an at least partly generally truncated cone shape.

The drill bit can be attached to a drill, which can be moveably operated in the axial direction of the drill bit to remove material from a partition. The drill bit in accordance with the invention is simpler than the aforementioned router.

The drill bit body may comprise a conical shape. Preferably, the drill bit body comprises only a truncated cone shape, i.e. the drill bit has no pointed tip. Such a pointed tip can cause damage to pipe work and electric's located behind a partition and unsighted to the user of the drill. s

The diameter of the drill bit body is preferably sufficient to enable a hole big enough for an adult person to pass their hand through it, e.g. to work on the blind side of t:le partition. The diameter of the body may be between 10 cm and 20 cm. Most preferably, the diameter of the body is between 10 cm and 15 cm.

The drill bit preferably has an integral hole saw blade at its foremost end. Such an integral hole saw blade permits, with just one drill bit, and in one single axial movement, a hole to be first drilled by the hole saw blade, and the hole then to be shaped by the at least partly generally truncated cone shape body.

The body preferably has material removal means. The material removal means preferably comprises a blade arrangement. The blade arrangement comprises at least one blade on the circular periphery of the body. In one preferred embodiment, the blade arrangement comprises three blades. In another preferred embodiment multiple blades are arranged to "grate" the partition material. Where a plurality of blades are employed, the blades are preferably equally spaced about the periphery of the body. The foremost centre point of the drill bit is blunt.

Instead of a blade arrangement, the material removal means may comprise abrasive naiads designed to wear away the material of a partition.

The drill bit preferably comprises a collar arranged to act as a depth stop. The collar preferably comprises a plurality of (integral) collar parts. The number of collar parts may correspond to the number of blades. The collar parts preferably define annular spaces between them to allow material surrounding a hole in a partition to be removed and to escape. Where a plurality of blades are employed, the spaces preferably coincide with the location of the blades. One preferred embodiment of the drill bit has three collar parts.

Where blades are not employed, a plurality of collar parts preferably defines a plurality of spaces.

The drill bit Is preferably fitted to an electrically powered drill. The drill bit can alternatively be arranged on a manually operated drill. The drill may be hand held or bench mounted.

According to a second aspect of the invention there is provided a drill having a drill bit in accordance with the first aspect of the invention fitted thereto.

According to a Bird aspect of the invention there is provided a plug for arrangement in a hole in a partition of a building such as wall, ceiling or floor, the plug having a generally truncated cone shape.

The plug is preferably of a diameter to fit a hole big enough for an adult persons' hand to pass through it. The plug diameter may be between 10 cm and 20 cm. Most preferably the plug diameter is between 10 cm and 15 cm.

The plug may comprise a periphery which is only in part a generally truncated cone, e.g. at a foremost narrow diameter end of the plug.

An edge delulcd by the rearmost larger diameter end of the plug and the conical surface of the plug may be rounded.

The plug may be made from MDF or plaster or any material with matches the partition material. The plug may be made of any material strong enough to bear the weight of a person once tle plug is installed in a partition.

According to a fourth aspect of the invention there is provided a partition having a hole therein, the hole comprising the plug in accordance with the third aspect of the invention fined therein.

The partition may have a hole of generally truncated cone shape or partly generally truncated cone shape. The plug is preferably adhered in place using glue. Alternatively tile plug may be frictionally located. The rear most end of the plug may lie approximate!! in line with the facing surface of the wall. The plug may be arranged to lie inbound ol the facing surface of the partition. For example, in one embodiment, the depth of the plug may be reduced with respect to the depth of the partition so as to permit the rearmost end of the plug to lie inbound of the facing surface of the partition.

The depth of tile plug may also be increased with respect to the depth of the partition.

The plug may be made of the same material as the partition.

According to a fifth aspect of the invention there is provided a kit of parts, the kit comprising a bit in accordance with first aspect of the invention and a plug in accordance with third aspect of the invention.

Preferably, tile kit comprises a plurality of similar plugs.

Preferably, the kit comprises a hole saw attachment for a drill.

Preferably, tile plug is manufactured to approximately match the dimensions of the body of the drill bit.

According to a sixth aspect of the invention there is provided a method of making a hole in a partition of a building, the method comprising fitting the drill bit in accordance with the first aspect of the invention to the drill, then arranging the drill bit in the hole, and using the drill bit, axially drilling to form a generally truncated cone shaped bore in the partition.

Preferably, the method includes the step of drilling a hole through the partition using a drill having a parallel sided hole saw attachment, So as to create the hole for the drill bit in accordance with the invention prior to drilling with the drill bit.

The method may further comprise repairing the hole by inserting a plug in accordance with the third aspect of the invention in to the tapered hole. Preferably the method comprises gluing the plug in the generally truncated cone shaped bore in the partition.

A bit and plug in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of a bit in accordance with the invention, Figure 2 is a view of the bit of Figure 1, taken in the direction of the arrows II-II, Figure 3 is a side view of a plug in accordance with the invention, Figure 4 is a view of the plug of Figure 3 taken in a direction of the arrows IV-IV, Figure 5 is a schematic view of a wall of a building, a hole in the wall having been shaped by the bit, and having the plug shown in Figures 3 and 4 installed therein, Figure 6 is a perspective view of an alternative embodiment of the bit (shown without a blade or mounting shaft), Figure 7 is a side view of the bit of Figure 6, Figure 8 is a view of the bit of Figure 7 taken in the direction of the Arrows VI-VI, Figure 9 is a view of the bit of Figure 7 taken in the direction of the arrows VIII-VIII, Referring to Figure 1, a drill bit 10 in accordance with the invention, comprises a shaft 12, and a collar 14 and a body 16 arranged coaxially therewith.

The shaft 12 has a hexagonal cross-section, seen by the hidden detail in figure 2, which allows it to be fitted to a hand held, electrically powered, drill.

The body 16 has a generally truncated cone shape. The diameter of the body 16 is conveniently about l5cm, although, functionally speaking, the diameter of the body need only be such as to provide a hole sized to allow a person to put their hand through a hole formeti in a partition by the drill bit body so as to carry out work on the blind side of the partition.

The body 16 comprises a blade arrangement, which, in the embodiment shown in Figures I and 2 of the drawings, comprises three blades 18 (only two are shown in Figure 1, and only one is shown in Figure 2) arranged on the periphery of the body. A different number of blades could be employed but, particularly with a body diameter of this size, three blades has been selected as an optimum number. The three blades 18 are equally spaced at intervals of approximately 120 degrees about the periphery of the body 16. Each of tle three blades 18 is arranged in a recess 20, formed in the body by any suitable means. Obviously, each blade 18 is arranged in its recess 20 so that the cutting tip of the blade protrudes beyond the periphery of the body 16. In the embodiment sloven the blades 18 are arranged at an angle of approximately 30 degrees to the tangent of the periphery of the body 16. Each blade 18 is removably fixed to the body 16 by screws 22 or other suitable fasteners. Cavities 24 precede the blades 18 to allow material surrounding a hole in a partition to be removed and to escape.

The collar 14 comprises a number of collar parts corresponding to the number of blades, i.e. ilk clue embodiment shown, three collar parts 26. The three collar parts 26 define annular spaces between them, of equal size, each of which spaces coincides with the location of one of the blades 18. Each collar part 26 extends for approximately 90 degrees of tile circumference of the body so as to, collectively, provide a collar 14 which acts as a reliable depth stop for the bit 10.

Referring to; igures 3 and 4, a plug 30 in accordance with the invention is manufactured to approximately matching dimensions to the body 16 of the bit 10. The plug 30 can be made of the same material as the hole which is filled, or conveniently made front MDF or plaster, or any other suitable material. However, in another embodiment. it should be noted that the plug need only have a periphery in part of generally truncated cone shape, e.g. at either a foremost (narrow diameter) end 32 of the plug (i.e. the ri Alit land side of the plug in Figure 3) or at a rearrnost end.

An edge 34 defiled by the meeting of the rearmost (larger diameter) end 36 of the plug (i.e. the loll hand side in Figure 3) and the conical surface of the plug may be rounded. Such a rounded edge 34 allows for a filler material to key into the space defined by the wall and the plug 30 when the plug is fitted into the hole. s

Figure 5 shows a partition such as a plasterboard wall 40. Initially, a conventional parallel sidled hole saw attachment of the correct size is fitted on a standard, hand held, electric drill (not shown for conciseness). The wall 40 is drilled through using the hole saw attaclu1ent leaving a parallel sided bore through the wall. Other means can be employed to csablish a hole in the partition, e.g. a hole can be hammered in the partition when it is made of plasterboard.

The drill bit 10 shown in Figures 1 and 2 can then be arranged on the drill and used to create a tapered hole 41 in the wall.

The drill bit 10 need only drill along part of the parallel sided hole in the wall, e.g. the foremost part of Me parallel sided hole, to provide a hole having at least a partly tapered profile. It may be convenient for the diameter of the hole formed by the hole saw attaclmlent to be slightly greater than the diameter of the foremost (narrow) end 32 of the drill bit 10 so as to allow the blades 18 of the drill bit to penetrate the hole and engage the material surrounding the hole which is to be cut. Such a relationship between the drill bit 10 and the parallel sided hole saw attachment can result in the furthest part of Bloc parallel sided hole remaining undrilled.

The depth of the plug may be reduced so as to permit the rear most end of the plug to lie inbox ot tile facing surface 42 of the partition. However, in the embodiment shown, the drill lit 10 bores substantially completely through the parallel sided hole in the wall, gin hip ise to a hole 41 of generally truncated cone shape. The collar 14 of the bit 10 acts as a ineptly stop, which results in a consistently accurate, standard sized / shaped hole regardless of the depth of the material being cut. This then allows the insertion of flee plug 30, foremost end 32 first, into the hole 41. The plug 30 can then be glued in place to create a strong surface repair. It can be seen that the rear most end 36 of the plug lies approximately in line with the facing surface 42 of the wall.

1 his tool / system allows the very quick cutting of any number of tapered access holes which can then be very quickly and efficiently repaired without the need of professional help or equipment. The advantages of the system are that it is quick, cost effective, involves mindlial damage to the partition, requires no other specialist tools, relatively cheap set up conies, eliminates the necessity of professional help such as plasterers, and is easily used by DIY enthusiasts, Only one sized plug 30 is required for repairing all floor repairs anti one for all plasterboard repairs. Indeed, a single size plug can be used for repairs to Iloors, walls and ceilings. A tapered plug of the sort described herein is stronger than a prior aut stepped plug, for example because the tapered plug uses the whole depth o'- the partition for the repair. Also, the tapered plug can be used to repair a partition of any thickness, even a very thin partition, because the partition will not be weakenci by the cutting of an over deep rebate in the partition.

The cenire of relic narrow end 32 of the body 16 may have a recess (not shown). The recess can take a nut. The end of the shaft 12 fitted to the collar (i.e. the end remote from the drill) can be passed through the collar and body and held in place by locating a nut in the recess and fastening the nut on a screw threaded portion of the shaft. The end of the shaft 12 which abuts the flange may be flared so as to strengthen the shaft. The shaft 12 can be elf circular cross section.

It should be appreciated that the body 16 may comprise abrasive means to grind away material i nstead of the aforementioned blades 18 which cut away material.

In an ahernativc embodiment of the invention, the electrically powered drill need not be hand lle'cl. Morcover, the drill bit 10 can be arranged on a manual drill.

The drill bit can take the fomm of a collar 14 and body 16 which is fitted to a commercially available 'hole saw arbour' as an alternative to the hexagonal shaft 12.

It has been found to be advantageous to fit the drill bit to a commercially available arbour which can be inexpensive to buy and are readily available to fit different sorts of drill chucks.

The blade arrangement comprises a single blade, Figure 6. Although the blade is not shown, the blade is fitted to a blade-ffxing block 100.

It has been found to be advantageous to use a single blade to eliminate judder, which can be associated with having a multiplicity of blades.

A counterbalance is provided 102.

When a single blade is used it can be advantageous to balance the drill body (Figure 6) by provision of a counterbalance 102. The counterbalance has a similar mass to the blade and blade-ffxing block 100. The counterbalance is conveniently a part of similar density and volume to the blade and blade-fixing block 100. The counterbalance can be positioned diametrically opposite the blade and blade-ffxing block. The counterbalance further improves the performance of the drill bit.

The collar arrangement comprises a single collar part 104.

The collar 104 and the body are made from a single piece of material (Figure 6).

The collar 104 and the body are cast in one piece (Figure 6)

Claims

Claims 1. A drill bits the body of the drill bit comprising an at least

partly, enera!!y trunk cone slope.

-

9. A drill bit accordin;, lo Clim l, wherein the diameter of the drill bit body is sufficient lo enable a hole big enough for an adult person to pass their hand rbroug,h it, preferublv between 10 cm and 20 cm.

lO 3. A trail bit according to any preceding claim, wherein the drill bit comprises material removal means, and the material removal means comprises a blade arrangement.

4. A drill bit according to Claim 3, wherein the blade arrangement comprises al least one blaJr on the circular periphery of the body.

5. A kill bit according to Claim 3, wherein the blade arrangement comprises du-e blades.

6. A drill bit according to Claim 4, wherein a plurality of blades are enployed, aild the blades are preferably equally spaced about the periphery of the body.

7. A drill bit according to Claim 1 or 2, wherein the drill bit comprises material remove' mealls, and the material removal means comprises abrasive means designed to wec- away tle material of a partition.

8. A drill hit according to any preceding claim, wherein the drill bit comprises a col'a: arrangel to act as a depth stop.

9. A drill bit according to Claim 8, wherein the collar comprises a plurality of collar parts.

10. A still bit according to Claim 8 or 9, wherein the number or collar p; l' correspc Is to the number of blades.

11. A fir 1 bit according to Claim 9 or 10, wherein the collar parts deigns cellular sp arcs between illem.

19 A ceil!' bi accordin=, to Claim 11, wherein the spaces coircide with the 1ocaion ol the by;!..

13. A.1!1 bit according A Claim 9 or 10 or 11, wherein the drill hit leas three colLIl parts.

14. A.:,1 bit accoriino lo any preceding claim, wherein the drill bit s fitted t electric,]:! powered drill.

IS. A c!1 bit according to any preceding claim, wherein the drill bit is Hanged fin nanuall! operated drill.

16. A Ll! Id" according to any preceding claim, wherein the drill is hand held.

17. A Jri!1 flit according to any preceding claim, wherein the drill is bench mounte;l.

1<'.. A d'1 havin' a drill bit in accordance with any one of Claims 1 to 17 rived thereto.

23 19. A 1 lor arrangement in a hole in a partition of a building such hi \vall, ceiling or floor, tle pluor having a generally truncated cone shape.

20. A 1!, according, to Claim 19, wherein the plug is of a diameter to Tat a hole Di ', enough for; adult persons' hand to pass through it.

21. A,, :;corlncr to Claim 19 or 20, wherein the plug comprises periphery wh ch is only '; -art a generally truncated cone.

r.l l] 22. A 1!lr " according to Claim 19, 20, or 21, wherein an edge defined by the rearmo, larger ill.. i,. !er end and the conical surface may be rounded.

23. A pled according to Claim 19, 20, 21, or 22, wherein the plug is Toledo from [Wolff.

24 A pa according to Claim lg. 20, 21, or 22, wherein the plug is Snide Mom plsr<:r.

25. A p:!-..,!1 for a building, the partition having a hole therein, the hole comprisin the plugs according to any of Claims 19 to 24 fused herein.

06. A pa!-,iion according to Claim 25, wherein the partition has a hole of generally, truncate.! A, _,!ape.

13 97. A l: r.:on;ccordino to Claim 26, wherein the partition has,1 ' ole of partly generally it rrcatcd cone shape.

08. A p,,':t,n according to any of Claims 25 to 97, wherein the p'u s adhered in place.

29. A p, In. according to any of Claims 25 to 28, wherein the rear most. end of the plug lice.ll!-.xUll.lcly in line with the facing surface of the partition.

:0. A p,!itni 'l according to any of Claims 25 to 29, wherein the plug is arranged to lie iboun.1 ol ' lacing' surface of the partition.

31. A 1'- a! a" according, to any of Claims 25 to 30, wherein the plug is made of the same n!ri. as Lie partition.

32. A lair i,' :. Is, Me lair comprising a bit in accordance with any of Claims 1 to 13 and a plug iJ! ..CL ".incC with any of Claims 19 to 24.

:3. A I: t ol parts according to Claim 32, wherein tile plug is r, lanufcrurr d; approxinare nlatcll the dimensions of the body of the drill bit.

34. A l. t or As according to Claim 39 or 33, wherein the Gil comprises tibia a\ attachment for a drill.

as. A memo ' t sllapin a hole in a partition, comprising, drillin I e Orally axle ts Toni iorn1 a,ecr 11, trulc;led cone shaped bore in the partition.

0 36. A net!i.' ol shaping a hole in a partition according to Claim 35, eompri ins t;iLlli, a drill bit in accordance with any of Claims 1 to 13 to the dell, anal ging the dril up i'! an existing 1lole in the partition, and drilling axially to form a gene-: 21\, trun bled Colt.

shaped bore. he partition.

37. A net!lod of shaping a hole in a partition of a building according to (flails. Rio, wherein to Netted further comprises repairing the hole by, nse:ing a aim i accordaicc \\ 1.h Claims 19 to 24 in to the tapered hole.

US. A new i Of makin, a hole in a partition of a building according to C"alr l, 0 wherein flee m Shod comprises gluing the plug in the generally Truncated cone s'aut:2.

bore in flee l:tirion.

By. A crlll l,r substantially as described herein and with reference to the accon: T ill drawings.

-

40. A plu, ubstantially as described herein and with reference w the accorllp;r 1'i, drawing s.

41. A merino; . t shaphlg a hole in a partition as described herein.

Amendments to the claims have been filed as follows: Claims 1. A drill bit else body of the drill bit comprising an a, least partly oener=!!y truncated cone sliale.

-

9. A dill bit according to Claim 1, wherein the diameter of the drill bit bodr is sufficient to Anile a hole big enough for an adult person to pass their hand through its preferallv betv'een 10 CIll and 20 cm.

3. A trail bit according to any preceding claim, wherein the drill bit comprises mareria! removal means, and the material removal means comprises a blade arrangement.

4. A drill bit according To Claim 3, wherein the blade arrangement comprises at least one blade on the circular periphery of the body.

5. A mill bit according to Claim 3, wherein the blade arrar.gemen comprises three blades.

6. A drill bit according to Claim 4, wherein a plurality of blades are employed, ally the blades are preferably equally spaced about the periphery of the body.

7. A drill bit according to Claim 1 or 2, wherein the dri!1 bit comprises material removal means, and the material removal means comprises abrasive means designed to wear away the material of a partition. 2:

8. A drill bit according to any preceding claim, wherein the drill bit comprises a collier arrangers lo act as a depth Slop.

9. A drill bit according to Claim 8, wherein the collar comprises a pi Gratify of collar parts. is

10. A stroll bit according to Claim g or 9, wherein the number OT coil' parts corresponds to the number of blades.

11. A fir;] I licit according to Claim 9 or 10, whereir the collar pEurrs define angular sp Ices between sheen.

A d^!'l lair according to Claim 11, wherein the spaces coincide with tale loca,in of [!le by!.

13. A.li'!1 bit according lo Claim 9 or 10 or 11, wherein the drill bit has three collar parts.

14. A c,i'1 bit accorlilg lo any preceding clairr, wherein the drill b'l s fitted to Al electric.,!. A powered drill.

15. A cii!1 bit accordrlgr to any preceding claim, wherein the drill bit is aITanged on a manual!! operated drill.

16. A d! !1 bit according to any preceding claim, wherein the dril! is hand held.

17. A dr,!1 bit according to any preceding claim, wherein the drill is bench mounted.

IS. A drip having a drill bit in accordance with any one of Claims 1 to 17 fitted thereto.

19. A 1 ^ for arrangement in a hole in a partition of a building such as wall, ceiling OF floor, else plug having a generally truncated cone shape.

90. A plot g according to Claim 19, wherein the plug is of a diameter to fit a hole Dig, enough lor,! adult persons' hand to pass Trough it.

01. A a, n.ccorling to Claim 19 or 20, wherein the plug comprises.peripher) which is only I;] ''am a.enerally truncated cone. lL

99. A ally according to Claim 19, 20, or 21, wherein an edge defined by the rearmosr larger di; : tar end and the co iical surface may be rounded.

23. A phi according to Claim 19, 20, 21, or 27, wherein the plug is made from Allele.

24 A p'u according to Claim lo, 20, 21, or 29, wherein tl e plug is made fiom plaster.

2. A 1,:!-', a n lor a building, The partition having a hole therein, the hole comprising the pluo according to ally of Claims 19 to 24 fined herein.

76. A pa!-rricl according to Claim 25, wherein the partition has a hole of generally truncate.0!'^ S]lOpe.

27. A it: Lion according to Claim 26, wherein the partition has a hole of partly genera] n L!!'CatCd cone shape.

28. A paf.,,on according to any of Claims 25 to 97, wherein the lam is adhered in place.

79. A p:!.iiOn according to any of Claims 25 to 28, wherein the rear most end of the plug lies.pproxillately in line with the facing surface of the partition.

30. A pal info l accordng to any of Claims 25 to 29, wherein the plug is Arranged to lie inbound o' .' e facing surface of the partition.

31. A l-- Ion:iccordina lo any of Claims 25 to 30, wherein the plug is made of the same ni!.r., as Else partition.

2. A Or Of I'.!' 'S. Ills kit comprising a bit in accordance with any of Clans 1 to 13 and a plug is..cc J.!nce wild any of Claims 19 to 74.

c (I 3. A l: t ol parts according to Clann 39, wherein The plug is manufactured w approxlilae match tile dimensions of the body of the drill bit.

34. A kit o+ Arts according to Claim 32 or 33, wherein the kit co.mpr ses a hole se\ attaclnnt for a drill.

As. A Trer'o ' ot soap a hole in a partition, comprising drills generally aX!ry co Arm a era r l] truncated cone shaped bore in the partition.

f 0 36. A mettle.' of shaping a hole in a partition accordir g to Claim,5, comprising whirl J. a drill bit in accordance with any of Claims 1 to 13 to the drill, Army the chril'i bit- in an existing, hole in the partition, and drilling axially to form a generally truncated cone shaped bore. flue partition.

37. A method of shaping a hole in a partition of a building according to Claim so, \Nhereiii th Method further comprises repairing The hole by inserting a 'lug i-? accordallce it. 1.'h Claims i 9 to ?4 in to the tapered hole.

o S. A rae.'o ' of retaking a hole in a partition of a building according to Cla m 37, wherein the method comprises gluing the plug in the generally Brenda ed con shaped bore in floe lo ition.

9. A drill b;r substantially as described herein and with reference to the accomp;a:ing drawings. ?5

40. A plug substantially as described herein and with reference To the acconr,p-lyh- drawings.

41. A method o shaping a hole in a partition as described herein. - It

_ - ' ^ ; ? 42. A drill bit according to any of Claims 1 to 14, wherein the drill bit is fined to a hole saw arbour.

43. A drill bit according to Claim 4, wherein the drill bit comprises only a single blade.

44. A drill bit according to Claim 43, wherein the blade is fitted to a blade-fixing block.

45. A drill bit according to Claim 44, wherein a counterbalance to the blade and blade-fixing block is provided.

46. A drill bit according to Claim 44 or 45 wherein the counterbalance is conveniently a part of similar density and volume to the blade and bladefixing block.

47. A drill bit according to any of Claims 1 to 17 or 42 to 46, wherein the collar and the body of the drill bit are made from a single piece of material.

48. A drill bit according to Claim 47, wherein the collar and the body are cast.