The present invention relates to the field of thread cutting, in particular a device for the application of a thread to the external surface of a conduit, use thereof and a kit of parts thereof.

Safety regulations in the United Kingdom (see Institution of Electrical Engineers Wiring Regulations, 16 ^th Edition) require that electrical cabling within boiler rooms and similar facilities are protected by steel conduit, typically galvanised or enamelled steel. The conduit provides a degree of protection against fire and physical damage. Although the actual diameter of the conduit is not specifically defined by law, a number of industry standard sizes have been developed, in particular 20 mm and 25 mm outer diameter (corresponding to approximately 17 mm and 21 mm internal diameter, i.e. 1.5 mm and 2 mm wall thickness respectively).

The path of the conduit must necessarily follow the desired cabling layout. However, the conduit is relatively inflexible and for practical reasons it is therefore common to combine the conduit with a range of joins, junctions and bends (typically manufactured by casting). At such discontinuities in the conduit, the integrity of the protection provided must be maintained. Typically, threading on the external surface of the conduit interfaces with threading on the internal surface of an orifice on the item to which the conduit is to be mated, providing a secure connection.

It is impossible to accurately predict the required length of a specific piece of conduit in advance, and unrealistic to expect that conduit manufacturers provide an infinite number of conduit lengths with pre-threaded ends. Conduit is normally supplied in defined lengths, for example 3.5 m, and is subsequently cut to an appropriate size on-site with threading then applied to the ends of the piece as is required.

Typically, threading is parallel and not tapered (i.e. fastening threads, rather than jointing threads). The threads normally extend approximately 20 mm from the end of the conduit, however, some joins require up to 45 mm of threading.

Those skilled in the art will recognise the broad range of threading styles available, either according to one of the many recognised standards (e.g. ISO 228-1 , BS2779) or of a proprietary nature.

Currently, threading is normally applied to the conduit manually using stocks and dies (Figure 1). Dies are available in a range of sizes and can be characterised primarily by: (i) the specific conduit diameter for which they are designed; (ii) the thread which they cut (i.e. thread profile, depth, taper and the number of threads per unit length). The precise nature of the dies can vary

considerably, for example the style of interface with the stock, tapering of the cutting surface to ease the threading process, or the presence of channels or voids to facilitate swarf clearance. Such features are well known to those skilled in the art.

Figures 2 and 3 show a selection of conventional cutting dies. A thread cutting surface (1) is located around the circumference of a central void (2) through which the conduit passes during the application of the threads. The nature of the cutting surface (1) defines the thread which is cut (i.e. thread profile, depth, taper and the number of threads per unit length), while the size of the central void (2) defines the size of conduit with which the die is to be used. Swarf clearance is facilitated by additional voids (3) which are arranged around the central void (2) and which interrupt the cutting surface (1 ). Since the dies in these figures are externally circular, a mechanism for securely engaging the dies with a holder or stock, for example a notch (4), is necessary such that a torque may be applied to the die.

By virtue of their role in cutting a thread in the conduit, dies must be manufactured from an appropriate material, such as hardened steel or coated steel.

A range of stock designs also exist, such as those with a single handle, those with a handle on either side of the die holder, and those which are capable of holding multiple dies. It is common that the stock incorporates a ratchet mechanism to avoid the need for repeated repositioning of the handle during the application of a thread.

In use (see Figure 4), a section of conduit (5) is typically held in a pipe vice (6), the die is positioned at the end of the conduit and torque is then applied to the die using the stock. This results in the die cutting into the external surface at the conduit end and the creation of the threading.

Stocks and dies suffer from a number of disadvantages. The steel typically used for conduit, although not hardened perse, is still a relatively hard material and threading requires substantial physical effort and time. Manual application of 15 mm of thread to the end of a 20 mm outer diameter conduit using stocks and dies typically takes 3 to 5 minutes. Due to the degree of freedom in the initial positioning of the die at the conduit end, stocks and dies are inconsistent in the accuracy of the threading produced. Mis-threading is a common occurrence and means that the conduit must be discarded, since removal of the mis-threaded end usually means that the conduit is then too short for its intended purpose. Mis-threading is often only apparent after the thread had been finished, thereby wasting time in addition to materials.

Powered threading tools can be divided into two main classes: firstly those which operate in a similar manner to a lathe (wherein the cutting bit/die is stationary and the conduit is rotated and

moved in relation to the bit/die) and secondly those in which the conduit remains stationary and the cutting bit/die is rotated and moved in relation to the conduit. Lathe style tools are inappropriate for general use due to their large weight and high cost. While portable examples of the second class of powered threading tools exist (see Figure 5), these are still cumbersome and, due to their high cost and restricted application, are not in common use.

Additionally, the swarf produced by both stocks and dies or powered threading tools can be messy and presents a safety hazard due to its fine size and sharp edges.

The present invention seeks to reduce or negate the difficulties associated with the state of the art by providing an inexpensive portable device, which, in combination with items of equipment in general use by those in the field, may be used to apply threading to the external surface of a conduit end.

According to the present invention there is provided a thread cutting device for applying an external thread to a conduit comprising:

(a) a cutting mechanism comprising a driving member capable of rotation about an axis which interfaces through a gearbox with a cutter body capable of rotation about an axis; which is slideably connected by means of at least one guide member to

(b) a clamp mechanism suitable for holding conduit in position for threading; and characterised in that the axis of rotation of the driving member is substantially co-axial with the conduit.

By the term cutter body, as used herein, is meant a component which comprises a thread cutting element which interfaces with the gearbox, such that torque which is transferred through the gearbox from the driving member causes the cutter body to rotate, and wherein the rotational motion of the cutter body enables the thread cutting element to function. Optionally, the cutter body interfaces with the gearbox via a detachable connection.

The cutter body may be formed from a single component or from the combination of multiple individual components. Preferably, the cutter body is formed from the combination of multiple components. In particular, it is preferred that the thread cutting element is removable from the cutter body and replaceable, in the event of wear, if the device is to be used to apply a different type of thread or to be used on a different size of conduit. Typically the thread cutting element will comprise a threading die of conventional design, such as those described previously and shown in Figures 2 and 3.

Where the thread cutting element is removable, the remainder of the cutter body will be designed to receive the die and may comprise additional components (such as screws) to hold the die in place. Preferably the cutter body will comprise one or more voids or channels for swarf clearance. An example cutter body is illustrated in Figure 6.

The cutter body should be configured such that in use, the conduit end does not contact the gearbox or cutter body during the application of the desired length of thread.

Optionally the cutter body may be covered by a safety sleeve (for example, see Figure 7. The safety sleeve may in fact serve a dual purpose of collecting swarf and guarding the moving cutter body from impingement.

The function of gearboxes is well known in the art. The gearbox of the thread cutting device is a step-down gearbox and serves to transfer torque applied to the driving member to the cutter body. Gearboxes comprise a multitude of gears, typically toothed cogs of varying sizes. Although it is well known that gears may engage such that rotation of a first gear causes rotation of a second gear in a different plane, for simplicity, it may be preferred that rotation of a first gear causes rotation of a second gear within the same plane. All of the gears in a gearbox may be separately arranged within a single plane. Alternatively, to aid in the construction of a compact device, gears may be arranged such that sprockets of differing sizes are located on the same spindle. Rotation of a first gear may therefore be transferred into a rotational movement of the second gear via the spindle. Although the gearbox may be designed such that the gear ratio may be adjustable to suit different conduit sizes or for different power sources, for simplicity of construction it is preferred that the gearbox has a fixed gear ratio.

The gearbox used in the present invention is ideally designed such that a balance is struck between the need for sufficient torque at the cutter body and the speed of rotation of the cutter body (which ultimately determines the time taken to cut the threading). To cut a typical thread on a 20 mm steel conduit requires in the region of 38 Nm. Therefore, depending on the torque and speed of rotation at the driving member, the gear ratio will generally be in the range of 8:1 to 20:1 , preferably 9:1 to 12:1, in particular around 9:1 or 10:1.

Gears, spindles and the gearbox casing are constructed from a material which can withstand the forces experienced, typically steel, though for certain applications where lower forces are required polymeric materials, such as nylon, or glass reinforced plastic may be sufficient. The gearbox casing may optionally be strengthened by the use of braces.

The driving member will typically be from 1 to 15 cm in length. Although driving members of circular cross-section may be suitable for use in the present invention, it is preferred that the

driving member is of non-circular cross section (for example, square, rectangular or hexagonal) and/or comprises notches/grooves (for example an SDS style connector) such that torque may be applied effectively to the driving member without the risk of slippage. The driving member will be suitable for attachment to a means of applying torque, such means being electrically powered (for example a conventional drill) or manually powered (for example a crank handle). In a preferred embodiment of the invention the driving member will be suitable for attachment to a drill or crank handle through which torque may be applied.

It is common that, in order to initiate the cutting process, force is applied to the thread cutting device along the axis of the conduit. To minimise the risk of off-axis forces being applied (which may lead to mis-threading), the driving member will be substantially co-axial (e.g. co-axial) with the axis of rotation of the cutter body, which in turn is substantially co-axial with the conduit.

The clamp mechanism may serve multiple purposes. Firstly, the relative arrangement of the clamp mechanism and cutting mechanism allows the cutting mechanism to be correctly positioned at the conduit end before threading begins. Secondly, in light of the slideable connection between the clamp mechanism and the cutting mechanism, off-axis movement of the cutting mechanism relative to the conduit is restricted during the threading process. Thirdly, the torque applied to the cutter body will tend to cause rotation of the cutting mechanism. Clamping of the conduit relative to the gearbox (save for the slideable connection) serves to avoid such rotation of the cutting mechanism.

The slideable connection between the clamp mechanism and the cutting mechanism may be achieved in a number of ways. Typically the connection will comprise at least one guide member which penetrates orifices or channels (or such like) in the clamp mechanism and cutting mechanism, and is parallel to the conduit. To ensure that the clamp mechanism can adequately assist in the correct positioning of the cutting mechanism at the end of the conduit, it is desirable that the freedom of motion, outside of slideable movement of the cutting mechanism towards and away from the clamp mechanism, is minimised. Undesirable movements can be restricted both by precision manufacture and from the use of multiple guide members. In one embodiment of the invention the thread cutting device comprises two guide members. In a further embodiment of the invention the thread cutting device comprises three guide members. Where multiple guide members are utilised, it is preferred that the multiple guide members are located around the conduit (i.e. the guide members and conduit do not all lie within a single plane, unless there are two guide members which are located on opposite sides of the conduit). Preferably the guide member or members will be attached (permanently or detachably) to either of the clamp mechanism or the cutting mechanism (but an individual guide member may not be attached to both). In one embodiment of the invention the guide member or members will be

attached to the cutting mechanism (for example, to the gearbox casing). In another embodiment of the invention the guide member or members will be attached to the clamp mechanism. Optionally, guide members may be joined at one or more positions along their length to provide additional structural strength. Guide members may be of circular or non- circular cross-section, for example they may be of square or rectangular cross-section, alternatively they may be in the form of beams (for example, I, H or L in profile). Figures 8 and 9 illustrate a number of possible arrangements of guide members.

A range of mechanisms are available for clamping the conduit, including a single moveable jaw, multiple moveable jaws (for example, two opposable moving jaws) or a split ring. To ensure that the clamp mechanism can adequately assist in the correct positioning of the cutting mechanism at the end of the conduit, the clamped conduit should be substantially co-axial (e.g. co-axial) with the axis of rotation of the cutter body.

The thread cutting device may be constructed for use with a single diameter of conduit. Preferably the thread cutting device will be constructed for use with a range of different diameters of conduit. If intended for use with a range of different diameters of conduit the thread cutting device must comprise means for ensuring that the conduit and axis of the cutter body rotation remain substantially co-axial when different diameters of conduit are clamped. For example, the clamp may be designed such that the conduit remains co-axial by the use of a system with multiple jaws or where specific spacers (or split rings) are utilised for each conduit size. Alternatively, the clamp itself may be moved relative to the cutter body, such as by system of multiple sets of orifices or channels for the guide member(s) (in either the cutting mechanism or clamp mechanism, as appropriate), or where the position of the orifices or channels are adjustable relative to the position of the clamped conduit. In one embodiment of the invention movement of the clamp jaws results in an associated movement of the orifices for the guide member(s). Figures 10 to 13 illustrate various possible clamp arrangements.

There is also provided a thread cutting device according to the present invention which comprises a clamp mechanism comprising multiple sets of orifices for guide members, such that a clamped section of conduit may be moved relative to the axis of rotation of the cutter body.

Typically the thread cutting device according to the present invention will be utilised for conduit of around 60 mm or less in outer diameter, for example around 50 mm or less in outer diameter.

To assist in the support and control of the thread cutting device, it is preferred that the cutting mechanism comprises a handle. Preferably the handle is a member which is positioned orthogonally to the driving member.

Torque may be applied to the driving member through a number of means. Due to the prevalence of such tools in the trade, torque is suitably applied by an electrically powered drill (mains or battery powered) or similar.

A range of drill types are readily available, for example 24Ov and 110v mains powered or 24v and 18v battery powered.

Drills are often supplied with an adjustable clamp, known as a chuck, but those of a professional standard may alternatively be supplied with an SDS connector. In normal use the chuck or SDS connector holds a bit, but in the context of the present invention may be utilised as a means for connecting the drill to the driving member. In combination with an appropriately specified step- down gearbox, most standard drill types will produce sufficient torque at the cutter body to enable the thread cutting device of the invention to work correctly. A high power output drill, in combination with a suitable gearbox, would be suitable for the application of threads to conduit with an outer diameter significantly larger than the typical sizes (for example 32 mm or 45 mm outer diameter conduit).

For circumstances where the user is unable to access a power source for a mains drill, or where there is insufficient charge in a portable battery powered unit, the thread cutting device may comprise a crank handle for connection to the driving member. Preferably the crank handle is detachably connected to the driving member. The thread cutting device may then be used through the manual application of torque to the driving member using the crank handle.

Optionally the thread cutting device may comprise a thread length guide, such that the thread length may be estimated without requiring the removal of the thread cutting device from the conduit end. In one embodiment of the invention the length guide is attached to a guide member. In a second embodiment of the invention the length guide is attached to the clamp mechanism.

Means may be provided such that thread cutting is stopped when a defined length of thread has been applied to the conduit. Automatic cut-off may be achieved through mechanical (when a predefined depth is obtained the cutter body is disengaged from the gearbox/driving member) or electrical (when a predefined depth is obtained the electrical supply to the drill is terminated) means.

Although not required, it may be beneficial that cutting fluid or paste is utilised to lubricate the cutting element and aid the thread cutting process.

As a further aspect of the present invention there is provided a kit of parts comprising:

(a) a cutting mechanism comprising a driving member capable of rotation about an axis which is connected through a gearbox to a cutter body capable of rotation about an axis;

(b) a clamp mechanism suitable for holding conduit; wherein the cutting mechanism and clamp mechanism are adapted such that they be slideably connected by means of at least one guide member, and further characterised in that the axis of rotation of the driving member is substantially co-axial with the conduit.

There is also provided a process for the application of a thread to the external surface of a conduit comprising the following steps: (a) providing a thread cutting device according to the present invention

(b) attaching the clamp mechanism to a section of conduit;

(c) locating the cutting mechanism at the conduit end;

(d) applying a torque to the driving member.

The invention is illustrated by reference to the following examples, in which:

Figure 1 shows a selection of prior art stocks and dies, by way of comparison to the present invention.

Figure 2 shows a selection of prior art dies of conventional design.

Figure 3 shows a selection of prior art dies of conventional design.

Figure 4 shows a section of conduit being held in a pipe vice.

Figure 5 shows an example of a prior art portable powered thread cutter, by way of comparison to the present invention.

Figure 6 illustrates a cutter body according to the present invention.

Figure 7 illustrates a safety sleeve according to the present invention.

Figure 8 shows a number of possible arrangements of guide members relative to the conduit.

Figure 9 shows a number of possible arrangements of guide members and different guide member styles.

Figure 10 shows a first clamp mechanism suitable for use with multiple conduit sizes.

Figure 11 shows a second clamp mechanism suitable for use with multiple conduit sizes.

Figure 12 shows a third clamp mechanism suitable for use with multiple conduit sizes.

Figure 13 shows a fourth clamp mechanism suitable for use with multiple conduit sizes.

Figure 14 shows a thread cutting device of the present invention.

Figure 15 shows an exploded view of the thread cutting device, with a set of additional components to adapt the device for use with an alternative conduit size.

Figure 16 shows a different exploded view of the thread cutting device.

Figure 17 shows the thread cutting device in position on a section of conduit which is clamped in a pipe vice.

Figure 18 shows the thread cutting device with a conventional drill attached to the driving member.

Figure 19 illustrates the thread cutting device of the present invention.

Figure 20 shows an external view of an example gearbox.

Figure 21 shows the internal arrangement of the gearbox.

Figure 22 is a view of the partially disassembled gearbox.

Figure 23 is an alternative view of the partially disassembled gearbox.

Figure 24 shows a side view of the thread cutting device with the gearbox internal components located outside the gearbox casing.

Figure 25 shows an expanded side view of the gearbox internal components.

Figure 26 shows a thread cutting device of the present invention, with a cutaway view of the gearbox and cutter body.

Figure 27 shows an alternative arrangement for the clamp mechanism.

One possible configuration of a cutter body is shown in Figure 6. The main wall (8) of the cutter body holds a die of conventional design (9) which comprises the cutting element (10). A cover piece (11 ) at the end of the cutter body comprises a central void through which the conduit may pass. The rotatable cutter body interfaces with the gearbox (20).

For safety reasons and to reduce the mess caused by swarf, an optional sleeve (7), such as that shown in Figure 7 may be utilised.

Guide members may be arranged in a number of ways. Figures δa to δc show a selection of arrangements of guide members (23) around the conduit (5). Figures δa to δc illustrate the use of guide members (23) which are of non-circular cross-section, such as I (Figure 9a), L (Figure 9b) or H (Figure 9c) beams.

Clamp mechanisms which are deigned for use with multiple diameters of conduit are illustrated in Figures 10 to 13. Figure 10 shows a clamp mechanism which may be used with two different conduit sizes. A moveable jaw (14) is adjusting using a handle (15) to clamp a section of conduit (5) in place. Two sets of orifices (13), through which guide members may be located, are positioned such that the clamped conduit is co-axial with the axis of rotation of the cutter body.

Figure 11 illustrates a clamp mechanism which may be utilised with a range of conduit sizes. Two movable jaws (14) may be adjusted using the handle (15) such that a section of conduit (5) may be clamped. The opposing jaws (14) ensure that a clamped section of conduit (5) will remain co-axial with the axis of rotation of the cutter body across a range of diameters of conduit.

Figure 12 illustrates an alternative a clamp mechanism which may be used with two different conduit sizes. Again, a moveable jaw (14) may be adjusted using a handle (15) such that a section of conduit (5) may be clamped. Two orifices (13) allow the clamp mechanism to be moved such that the conduit remains co-axial with the axis of rotation of the cutter body when the clamp is used with

Figure 13 shows a clamp mechanism wherein a section of conduit (5) is held in the clamp by a split ring (16). The handle (15) allows the split ring to be compressed or relaxed, and the split ring may be replaced with an alterative ring if the clamp is to be utilised with different diameters of conduit.

A photograph of a thread cutting device according to the present invention is shown in Figure 14. The section of conduit (5) is held in place using, for example, a pipe vice (not shown). The clamp mechanism (17) is attached to the section of conduit and the guide members (23) penetrate orifices in the clamp mechanism. The cutting mechanism, comprising the driving member (21), gearbox (20), rotatable cutter body (1δ) with swarf clearance channels (19) and handle (22) is slideably connected via the guide members (23) to the clamp mechanism (17).

Figures 15 and 16 show exploded views of a thread cutting device according to the present invention. In addition to the components already described, the die of conventional design (25) (which comprises the cutting element), cover piece (11) and split ring (27) may be seen in Figures 15 and 16. Figure 15 also illustrates how a thread cutting device can be easily adapted for use with an alternative diameter of conduit by replacement of the die (25), cover piece (11) and split ring (27) with those tailored for a different conduit size.

Figure 17 shows a thread cutting device according to the present invention (28) in place at the end of a short section of conduit (5) which is held in a pipe vice (6).

Figure 18 illustrates the thread cutting device with a conventional drill (29) attached to the driving member.

A line drawing of the thread cutting device is shown in Figure 19. The cutting mechanism may be correctly positioned at the end of the conduit (5) by inserting the guide members (23) into the orifices (13) in the clamp mechanism (17).

Figure 20 shows an example gearbox (20). The gearbox (20) may be opened by the removal of retaining bolts (33). Figure 21 shows the internal arrangement of the gearbox (20) following the removal of the gearbox cover (34) from the gearbox casing (35). Figures 22 and 23 illustrate a partially disassembled gearbox, where three of the gears have been removed along with the gearbox cover (34). The fourth gear (32) remains in the gearbox casing and is connected to the cutter body (18).

Figures 24 and 25 show how the gearbox connects the driving member (21 ) to the cutter body (18) via four gears (30). A brace (31) is provided for additional strength. Rotation of the driving member (21) causes the first gear to rotate. The first gear interfaces directly with a co-planar second gear, which in turn transfers rotational motion to a co-axial third gear. The third gear then interfaces with a co-planer fourth gear which is attached to the cutter body (18). It should be noted that for reasons of compactness the fourth gear and first gear are co-axial in the embodiment shown, despite this, there is no direct connection between them as they independently rotate about the same axis on separate bearings.

Figures 26 and 27 illustrate a further example of a clamp mechanism. In this example the clamp mechanism is designed for use using two guide members (23), and therefore has two appropriately positioned orifices (13) through which said members may pass. A movable jaw (14) is adjusted using a handle (15) such that a section of conduit (5) is held between the movable jaw and a member (36) which is positioned on the opposite side of the conduit. The clamp mechanism may be utilised with conduit of different diameters through appropriate

adjustment of the location of the member (36) via nuts (37), thereby ensuring that the conduit (5) remains substantially coaxial with the cutter body when clamped.

The gearbox shown in the figures is illustrative of one possible design only, other designs may be contemplated.

Referring to Figures 17 to 19, in use a section of conduit (5) is first held securely in place, such as in a pipe vice (6). The clamp mechanism (17) is subsequently firmly attached to the conduit (5) and, through the slideable connection of guide members (23) and orifices (13), aids the precise positioning of the cutting mechanism at the end of the conduit such that the cutter body (18) is substantially co-axial with the conduit (5). Torque may then be applied to the driving member (21), which is transferred through the gearbox (20) to the cutter body (18). Rotation of the cutter body (18) causes the cutting mechanism to move towards the clamp mechanism (17) along the axis of the conduit (5) and to cut a thread in the conduit. It may initially be necessary to apply a force on the cutting mechanism, along the axis of the conduit (5), to ensure that the cutter body (18) engages properly with the external surface of the conduit (5).

Where the torque is applied using a Bosch GBH2-22RE drill and thread is cut to a depth of 40 mm on a 25 mm outer diameter conduit, the thread cutting process may typically be completed within approximately 40 seconds.

The Bosch GBH2-22RE (which is shown in Figure 18) is a 620 W/110 v mains powered drill, which produces a torque of approximately 18 Nm.

Although the thread cutting device of the invention is described by reference to its application in conduit threading, it is clear that the device could additionally be utilised for the application of threading to other hollow or solid elements of circular cross-section, for example, in model building or carpentry. The term conduit is thereby meant to include any such pipes or rods which may require the application of an external thread.

The thread cutting device according to the present invention may also be used for the preparation of short sections of fully threaded conduit, for example 2-10 cm in length. Such short sections of fully threaded conduit are of use as running couplers, for example in the connection of two items such as a conduit box and section of conduit where the section of conduit cannot simply be threaded into the conduit box (e.g. where the conduit has a bend). A short section of fully threaded conduit may be prepared by the application of the thread to a larger piece of conduit, followed by cutting the short threaded section from the larger piece of conduit.

In the examples illustrated herein the clamp mechanism and mechanism for holding the conduit firmly in place (such as a pipe vice) are separate entities. It will be clear to those skilled in the art that the clamp mechanism could be integrated with an adapted pipe vice (i.e. the clamp mechanism comprises a pipe vice), and guide members provide a slideable connection between the adapted pipe vice and cutting mechanism.

The devices of the present invention are portable and are generally much smaller in physical dimensions and/or weight than devices of the prior art.

The term 'substantially', as used in respect of the axis of rotation of the driving member being substantially co-axial with the conduit, means that embodiments wherein the axis of rotation of the driving member is not co-axial but behaves for the purposes of the invention as if it were coaxial are included within the scope of the invention. The axis of rotation of the driving member is substantially co-axial with the conduit to avoid the application of significant off-axis forces during use of the device. For example, deviation of the axis of rotation of the driving member from a co-axial position is suitably less than 1 cm, more preferably less than 0.5 cm and in particular less than 0.1 cm (in the region of the driving member). Ideally, the axis of rotation of the driving member is co-axial with the conduit.

The term 'substantially', as used in respect of the axis of rotation of the cutter body being substantially co-axial with the clamped conduit, means that embodiments wherein the axis of rotation of the cutter body is not co-axial but behaves for the purposes of the invention as if it were co-axial are included within the scope of the invention. The axis of rotation of the cutter body is substantially co-axial with the conduit to ensure that the threads which are cut are within the required tolerances. For example, deviation of the axis of rotation of the cutter body from a co-axial position is suitably less than 0.5 mm, in particular less than 0.2 mm in the region of the conduit end where the threading is to be applied. Ideally, the axis of rotation of the cutter body is co-axial with the conduit.

All references referred to in this application, including patent and patent applications, are incorporated herein by reference to the fullest extent possible.

Throughout the specification and the claims which follow, unless the context requires otherwise, the word 'comprise', and variations such as 'comprises' and 'comprising', will be understood to imply the inclusion of a stated integer, step, group of integers or group of steps but not to the exclusion of any other integer, step, group of integers or group of steps.