Patent Publication Number: US-2023151693-A1

Title: A drill

Description:
TECHNICAL FIELD 
     The present disclosure relates to a drill and a method of using a drill. 
     BACKGROUND 
     Rotary drilling typically requires a large overhead force to push the drill into a substrate. Percussive drilling usually requires a lower overhead force to operate, but its penetration rate in rocks is often poor, and may only be effective at shallow depths. Rotary-percussive drills are able to use the rotary technique to drill significant depths, with the addition of percussive shocks reducing the overhead requirement, though they can be heavy, complex systems. There remains a need for developments in this field. 
     SUMMARY OF THE INVENTION 
     According to the present disclosure, there is provided a drill comprising: a drill bit comprising a first drill part and a second drill part configured to slide relative to each other, wherein the first and second drill parts are pivotally coupled at one end to a first member and a second member respectively; a cam engaged with the first member and the second member, wherein the first and second members act as followers to slide the parts of the drill bit in a reciprocating motion with respect to each other, between a retracted and an extended position; and a wedge comprising a first angled surface engaged with the first member and a second angled surface engaged with the second member, the wedge configured to urge the drill bit to pivot in a first direction when the first member is moved towards the retracted position and to pivot in a second direction when the second member is moved towards the retracted position. 
     The cam may be a cylindrical cam and the first and second members may extend on opposite sides of the cylindrical cam to transform rotational movement of the cylindrical cam to a linear reciprocating motion of the first and second members. 
     The drill may further comprise a motor to actuate both the reciprocating and pivot motions. 
     The first and second angled surfaces of the wedge may be a pair of surfaces having the same angle of incline, such that, in use, an angle through which the drill bit pivots in the first direction may be the same as an angle through which the drill bit pivots in the second direction. 
     The first member may comprise a hinge joint to pivotally couple to the first drill part and the second member may comprise a hinge joint to pivotally couple to the second drill part. 
     The hinge joint may comprise rounded contact points that engage each angled surface of the wedge. 
     The drill may further comprise a biasing means acting on the first and the second member to urge the first and the second members towards engagement with the angled surfaces of the wedge. 
     The first drill part may be coupled to the second drill part by an interlocking connection that may prevent lateral movement or rotation of the first drill part relative to the second drill part. 
     One of the first drill part and the second drill part may comprise a pin and the other of the first drill part and the second drill part may comprise a track, wherein the pin may be configured to travel within the track. 
     The drill may further comprise a chamber for the ingress of material to be sampled. 
     The drill may further comprise an openable cover to open and close the chamber. 
     The chamber may be provided at a location between the wedge and the cam, wherein the wedge may be closer to the drill bit than the cam. 
     The drill may further comprise a guide member for engagement with the first member and the second member. The guide member may comprise slots, and the first member and the second member may be configured to slide within said slots to guide the reciprocation motion. The guide member may be a sleeve disposed within an outer shell of the drill. 
     The drill may comprise a sealed housing to encapsulate the first and second members, the wedge and the cam, which may protect them from external environmental conditions. 
     According to the present disclosure, there is also provided a method of using the drill, wherein the method comprises: rotating the cam engaged with the first member and the second member, wherein the first and second members act as followers to slide the parts of the drill bit in a reciprocating motion with respect to each other, between a retracted and an extended position; and sliding one part of the drill bit into the retracted position, wherein the wedge urges the drill bit to pivot in a first direction as the first member is moved towards the retracted position and/or sliding the other part of the drill bit into the retracted position, wherein the wedge urges the drill bit to pivot in a second direction as the second member is moved towards the retracted position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which: 
         FIG.  1    shows a drill according to an embodiment of the invention; 
         FIG.  2    shows a drill bit of the drill of  FIG.  1    comprising first and second parts; 
         FIG.  3    shows an interlocking mechanism of the drill bit of  FIG.  2   ; 
         FIG.  4    shows a cam and follower mechanism of the drill of  FIG.  1    to provide reciprocal motion to a first and second member; 
         FIG.  5    shows an oscillating mechanism of the drill of  FIG.  1    comprising a wedge; 
         FIG.  6   a    shows the drill bit of  FIG.  2    in a neutral position; 
         FIG.  6   b    shows the drill bit of  FIG.  2    in a first position; 
         FIG.  6   c    shows the drill bit of  FIG.  2    back in a neutral position; 
         FIG.  6   d    shows the drill bit of  FIG.  2    in a second position; 
         FIG.  7 A  shows a schematic view of an embodiment of the invention comprising a sampling chamber; 
         FIG.  7 B  shows a schematic view of the sampling chamber of  FIG.  7 A  surrounded by a hollow outer shell; 
         FIG.  8    shows a schematic view of an embodiment of the invention comprising a sleeve that guides the first and second members; 
         FIG.  9    shows an embodiment comprising the drill mounted on a vehicle; and 
         FIG.  10    shows a flowchart of a method of using the drill. 
     
    
    
     DETAILED DESCRIPTION 
     The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in the specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. 
     In the description and drawings, like reference numerals refer to like elements throughout. 
     Drilling systems play a critical role in planetary exploration missions. Rotary drills are commonly used in terrestrial applications, however the large masses needed to provide the overhead force necessary to push the drill into the substrate make them less suitable for planetary exploration. For example, both the stringent mass constraints imposed upon a mission and low gravity on some other bodies such as the Moon and Mars may make at least some rotary drills unsuitable for such applications. 
     Percussive drilling involves vibrating the drill bit. Whilst percussive drilling typically requires a lower overhead mass to operate, its penetration rate in rocks is often poor, and may only be effective at relatively shallow depths. Rotary-percussive drills are able to use the rotary technique to drill significant depths, with the addition of percussive shocks reducing the overhead requirement. Despite being heavy, complex systems, they have been used on several space missions. 
     The terms substrate, material, rock, medium and drilling medium as used herein are generally interchangeable and refer to a medium through which a drill is operating a drilling action. 
     The term drilling action as used herein generally refers to an operation of a drill in a medium, for example to form a bore in the medium. 
     A drill  1  according to a first embodiment is described herein with reference to  FIGS.  1  to  7   . 
       FIG.  1    shows a drill  1  for providing reciprocation and oscillation motion. The drill  1  comprises a drill bit  2 , an actuation mechanism  3  and a stem  4  extending between the drill bit  2  and the actuation mechanism  3 . The drill comprises a housing  43  including a cylindrical hollow outer shell of the stem  4  and a casing  51  of the actuation mechanism  3 . 
       FIG.  2    shows the drill bit  2  in more detail. The drill bit  2  comprises a first drill part  7  and a second drill part  8 , herein referred to as a first part  7  and a second part  8  for ease of description. As illustrated in  FIG.  2    the first part  7  comprises one half of the drill bit  2  and the second part  8  comprises a second half of the drill bit  2 . The drill bit  2  comprises a tip  10  at its distal end, and a base  5  at its proximal end. 
     The term proximal as used herein is intended to mean a direction away from the tip  10  of the drill bit  2 . The term distal as used herein is intended to mean a direction towards the tip  10  of the drill bit. 
     The first part  7  comprises a first mating face  11  and a first external face  12 , the second part  8  comprises a second mating face  13  and a second external face  14 . The first part  7  is configured to engage the second part  8  at their respective mating faces  11 ,  13 , via an interlocking connection  15  (shown and further described in reference to  FIG.  3   ), such that the first part  7  is configured to slide relative to the second part  8 . The mating faces  11 ,  13  are substantially flat surfaces, such that when the mating surfaces  11 ,  13  are engaged, there is negligible space between them. This tends to prevent any material from being caught between the mating faces  11 ,  13  which may affect the sliding motion of the first and second parts  7 ,  8 . 
     The first part  7  is pivotally coupled at its base  5  to a first member  22  by a hinge joint or oscillating rod  6 , and the second part  8  is pivotally coupled at its base  5  to a second member  23  by a hinge joint or oscillating rod  6 . The first and second members  22 ,  23 , extend linearly through the stem  4 , away from the drill bit  2  to the actuation mechanism  3 . The first and second members  22 ,  23  are moved by the actuation mechanism  3  (described in more detail below with reference to  FIG.  4   ) in a reciprocating motion, to slide the first part  7  and the second part  8  of the drill bit  2  relative to each other. 
     Each of the first part  7  and the second part  8  further comprises a plurality of teeth  9  on the external face  12 ,  14 . The teeth  9  of the first part  7  are substantially symmetrical to the teeth  9  of the second part  8 . The teeth  9  extend away from the tip  10  of the drill bit, in a proximal direction, and are spaced along a length of the first part  7  and the second part  8 . The teeth  9  reduce in pitch size towards the tip  10 . The teeth  9  are configured to engage a surrounding substrate during a drilling action. Advantageously the teeth  9  can be customised for the particular medium to be drilled. 
       FIG.  3    shows a more detailed view of the interlocking connection  15  that seeks to prevent lateral movement or rotation of the first part  7  relative to the second part  8 . One of the first part  7  and the second part  8  comprises a pin  16 , and the other of the first part  7  and the second part  8  comprises a slot or track  17 . In the embodiment illustrated in  FIG.  3    the first mating face  11  comprises the track  17  and the second mating face  13  comprises the pin  16 . The pin  16  engages the track  17  and is moveable is between a distal position where the pin is  16  is located in a first end  18  of the track  17 , to a proximal position where the pin  16  is located in a second end  19  of the track  17 . 
     The pin  16  comprises a head  20  and a neck  21 , wherein the neck  21  extends between the head  20  and the mating face  13 . The head  20  has a larger cross sectional area than the neck  21  and the track  17  has a shape complimentary to the head  20  of the pin  16  that narrows around the neck  21 , such that the head  20  can be fully retained within the track  17 . The first part  7  is therefore able to slide with respect to the second part  8 , but is prevented from separating from the second part  8 . As illustrated in  FIG.  3    the head  20  and track  17  are rounded in shape, substantially spherical. 
       FIG.  4    shows the actuation mechanism  3  of the drill  1  in more detail. The actuation mechanism  3  comprises a cylindrical cam  24  engaged with the first and second members  22 ,  23 , and a motor  25  to actuate both the reciprocating and oscillation motion of the drill  1 . Rotational movement of the motor  25  is transformed into reciprocation motion of the first and second members  22 ,  23  by the cam  24 , wherein the first and second members  22 ,  23  act as dual followers. 
     The proximal end of the first member  22  comprises a first follower portion  26  and the proximal end of the second member  23  comprises a second follower portion  27 . The follower portions  26 ,  27  are each angled away from a central axis  28  of the drill  1 , to extend on opposite sides of the cam  24 . The follower portions,  26 ,  27  comprise at least one follower protrusion  29 , which engages with a groove  30  of the cam  24 . 
     As the cam  24  is continuously rotated by the motor  25 , both follower portions  26 ,  27  are moved forwards in a distal direction and backwards in a proximal direction, with an amplitude that is a function of the slope of the groove  30  of the cam  24 . The reciprocating movement of the first and second follower portions  26 ,  27  provides linear reciprocating movement to the first and second parts  7 ,  8  of the drill bit  2  respectively. Where the first part  7  or the second part  8  of the drill bit  2  is in its proximal most position, this is the retracted position. Where the first part  7  or the second part  8  is in the retracted position, the other of the first part  7  or the second part  8  is in its distal most position, the extended position. Therefore, the reciprocating movement of the first and second follower portions  26 ,  27  provides linear reciprocating movement to the first and second parts  7 ,  8  between a retracted position and an extended position. This is described in more detail with reference to  FIG.  6   a    to  FIG.  6     d.    
     The actuation mechanism  3  is located away from the medium to be drilled, at a proximal end of the drill  1 , to avoid any particles or dust created from the drilling action, or present in the medium, from affecting the actuation mechanism  3 , particularly the motor  25 . 
       FIG.  5    shows a wedge  32  of the drill  1 , for providing oscillation movement to the drill bit  2  of the drill  1 . The wedge  32  is disposed close to the base  5  of the drill bit  2  and between the first member  22  and the second member  23 . The wedge  32 , comprises a first angled surface  33  engaged with the first member  22  and a second angled surface  34  engaged with the second member  23 . The wedge  32  is configured to urge the drill bit  2  to pivot in a first direction when the first member  22  is moved towards the retracted position and to pivot in a second direction when the second member  23  is moved towards the retracted position (as shown in  FIG.  6   a    to  FIG.  6   d   ). This movement can be referred to as an oscillation or vibration motion. 
     Particularly, it is the oscillating rods  6  of the first and second members  22 ,  23  that engage the wedge  32 . The oscillating rods  6  comprise contact points  38 , in the form of protrusions or pins, which engage and slide along the angled surfaces  33 ,  34 . As the reciprocating first and second members  22 ,  23 , cause the contact points  38  to slide along the first and second angled surfaces  33 ,  34  of the wedge  32 , the first and second members  22 ,  23  pivot about the oscillating rods  6 . 
     The first angled surface  33  is symmetrical to the second angled surface  34 . The first and second angled surfaces  33 ,  34  of the wedge  32  are a pair of surfaces having the same angle of incline, such that, in use, an angle through which the drill bit  2  pivots in the first direction is the same as an angle through which the drill bit  2  pivots in the second direction. 
     The drill  1 , further comprises a biasing means  44 , for example but not limited to a torsional spring or elastic member, acting on the first and the second members  22 ,  23  to urge the first and the second members  22 ,  23  towards engagement with the angled surfaces  33 ,  34  of the wedge  32 . With the aid of the biasing means  44 , the contact points  38  maintain continuous and full contact with the wedge  32  during a drilling operation. The oscillating rods  6  pivot about the hinge axis  49 . Where the biasing means  44  is a torsional spring the torsional spring axis is at the same point as the hinge axis  49 . 
     While the reciprocation motion mainly depends on the slope of the groove  30  of the cam  24 , the oscillation or vibration motion depends on both the slope of the groove  30  of the cam  24  and the angle of the first and second angled surfaces  33 ,  34  of the wedge  32 . 
     The first and second members  22 ,  23  also comprise supports  47  which are configured to contact and slide along an inner surface  48  of the outer shell of the stem  4 . Advantageously the supports  47  improve the reciprocation motion of the first and second members  22 ,  23  within the stem  4 . The supports  47  may be for example but not limited to pins, protrusions or bearings. 
       FIGS.  6   a  to  6   d    shows the reciprocation and oscillation motion of the drill bit  2  as the drill  1  is operating. 
       FIG.  6   a    shows the drill bit  2  in a neutral position. The neutral position is where neither the first part  7  nor the second part  8  is in the retracted or extended position. The contact points  38  of the first and second members  22 ,  23  are at the same position along the angled surfaces  33 ,  34  of the wedge  32 , and therefore the drill bit  2  is not rotated towards a first direction or a second direction. The tip  10  and the base  5  of each of the first part  7  and the second part  8  are aligned. 
       FIG.  6   b    shows the drill bit pivoted in a first direction. As the cam  24  is rotated, the first follower  26  moves the first part  7  from the neutral position shown in  FIG.  6   a   , towards the retracted position and the second follower  27  moves the second part  8  towards the extended position. The contact point  38  of the first member  22  is moved along the first angled surface  33 , towards a proximal end of the wedge  32 . The contact point  38  of the second member  23  is moved along the second angled surface  34  towards a distal end of the wedge  32 . In this position the oscillating rods  6  are rotated with respect to the first and second members  22 ,  23 , to pivot or swing the drill bit  2  in the first direction. 
       FIG.  6   c    shows the drill bit  2  back in the neutral position. As the cam  24  is rotated further, the first follower  26  moves the first part  7  from the retracted position shown in  FIG.  6   b   , distally towards the neutral position and the second follower  27  moves the second part  8  proximally towards the neutral position. The contact points  38  of the first and second members  22 ,  23  are at the same position along the angled surfaces  33 ,  34  of the wedge  32 , and therefore the drill bit  2  is not rotated towards a first direction or a second direction. The tip  10  and the base  5  of each of the first part  7  and the second part  8  are again aligned. 
       FIG.  6   d    shows the drill bit pivoted in a second direction. As the cam  24  is rotated the first follower  26  moves the first part  7  from the neutral position shown in  FIG.  6   c   , towards the extended position and the second follower  27  moves the second part  8  towards the retracted position. The contact point  38  of the first member  22  is moved along the first angled surface  33 , towards a distal end of the wedge  32 . The contact point  38  of the second member  23  is moved along the second angled surface  34  towards a proximal end of the wedge  32 . In this position the oscillating rods  6  are rotated with respect to the first and second members  22 ,  23 , to pivot or swing the drill bit  2  in the second direction, opposite to the first direction. 
     As the cam  24  is rotated further, the first follower  26  moves the first part  7  from the extended position shown in  FIG.  6   d   , proximally towards the neutral position of  FIG.  6   a    and the second follower  27  moves the second part  8  distally towards the neutral position of  FIG.  6   a   . The oscillation cycle can then be repeated. 
     During the operation of the drill as described with reference to  FIG.  6   a    to  FIG.  6   d   , as the first part  7  moves proximally the teeth  9  engage with the surrounding substrate, creating a traction force that is then transferred to a penetration force in the second part  8  that is moving distally. This assists the drill bit  2  to push further into the substrate or medium being drilled. Advantageously the ability to self-generate a penetration force greatly reduces the need for additional masses to create an overhead force, thus presenting a compact and lightweight drilling solution. Advantageously integrating the oscillation or vibration movement of the drill bit  2  swinging in a first and second direction with the reciprocation motion of the first and second members  22 ,  23  seeks to improve the drilling performance. Combining the oscillation motion with the reciprocation motion can enhance the penetration rate and reduce the drilling time and power of the drill  1 . 
     As illustrated in  FIG.  7 A , in some embodiments, the drill  1  includes a sampling chamber  39  and an openable cover  35  (or openable shutter) to open and close the sampling chamber  39  for the ingress of material to be sampled. More particularly, the openable cover  35  opens and closes an aperture  52  in the stem  4  which provides access to the sampling chamber  39 . The sampling chamber  39  is provided in the stem  4  at a location between the wedge  32  and the cam  24 , wherein the wedge  32  is closer to the drill bit  2  than the cam  24 . The drill  1  also comprises an access cover  46 , to enable access to sampling chamber  39  to retrieve the sample. 
     The openable cover  35  is opened and closed by a latch which is moved by a linear actuator  37  (shown in  FIG.  4   ) provided in the drill  1 . The linear actuator  37  is located at a proximal end of the drill  1 , such that it is located away from the medium to be drilled to avoid any particles or dust from the medium from affecting or damaging the linear actuator  37 . The proximal and distal end of the sampling chamber  39  is sealed with a sealing member  45 . The sealing member  45  aims to retain the sample within the sampling chamber  39 . The sealing member  45  may be, for example but not limited to, a rubber bung or alternative polymer component. 
     Advantageously the openable cover  35  of the sampling chamber  39  may be opened for the ingress of material to be sampled at predefined depth, after penetrating the medium. As shown in  FIG.  7 A , the sampling chamber  39  has a length much greater than its width or diameter such that it provides enough space for the samples, but remains within the limits of the stem  4 . This way the sampling chamber  39  does not cause a protuberance in the stem  4 , which could impede the drilling action of the drill  1 . 
       FIG.  7 B  shows how the sampling chamber  39 , openable cover  35  and access cover  46  are positioned in the hollow cylindrical outer shell of the stem  4 . The access cover  46  is openable by screws which are fixed in place during a drilling operation, alternatively opening the access cover  46  may be automated or latched. 
     As illustrated in  FIG.  8   , in some embodiments the drill  1  comprises a guide member  40  surrounding the first and second members  22 ,  23 . In the illustrated embodiment the guide member is a sleeve  40 . The guide member  40  comprises slots  50  for receiving the first and second members  22 ,  23 . The guide member  40  is fixed within the outer shell of the stem  4 . The first and second members  22 ,  23  are configured to slide within the slots  50  of the guide member  40 , which guides the reciprocation motion of the members  22 ,  23 . This enables an optimised reciprocation motion and therefore enhances the efficiency of the system by reducing power losses in operating the drill. 
     As illustrated in  FIG.  9   , the drill  1  can be mounted on, or integrated with, a vehicle. One example application for the drill  1  is use in space. In such an application, the vehicle can be a rover  36  for driving over rough extra-terrestrial terrain by remote control. Advantageously for space, the drill  1  is lightweight and can be launched in a compacted form and then deployed on the extra-terrestrial terrain when needed for use. Due to the lightweight and compact nature of the drill  1 , the rover  36  can be equipped with more than one drill  1 . This will maximise the amount of samples which can be acquired in the duration of a space mission. 
       FIG.  10    is a flowchart of a method, indicated generally by the reference numeral  45 , in accordance with an example embodiment. The method  45 , shows how the drill  1  according to any embodiment described herein, may be used. The method  45  starts at operation  46 , where the cam  24  engaged with the first member  22  and the second member  23  is rotated, wherein the first and second members  22 ,  23  act as followers to slide the parts  7 ,  8  of the drill bit  2  in a reciprocating motion with respect to each other, between a retracted and an extended position. At operation  47 , one part of the drill bit  2  is slid into the retracted position, wherein the wedge  32  urges the drill bit  2  to pivot in a first direction as the first member  22  is moved towards the retracted position and/or the other part of the drill bit  2  is slid into the retracted position, wherein the wedge  32  urges the drill bit  2  to pivot in a second direction as the second member  23  is moved towards the retracted position. 
     In some embodiments the drill  1  is sealed and entirely encapsulated to protect it from external environmental conditions. In some embodiments it is the housing  43  which is entirely encapsulated. This is particularly relevant when the drill  1  is to be used in a location comprising tough environmental conditions, for example but not limited to, in space and in harsh weather conditions. The drill  1  may also be water tight for drilling in an underwater environment. 
     Advantageously the drill  1  provides a practical and durable design, having fewer moving parts than at least some prior art solutions. Having fewer moving parts can mean that the drill is less vulnerable to jamming and/or breakage. The drill  1  is also simpler to manufacture and assemble. Advantageously, a single motor may be used for both the reciprocation and oscillation motions described above. The drill  1  is compact and portable for attachment to other devices, or for use in many different locations. Advantageously the drill  1  is simple to deploy for use and stow when not in use. The drill  1  is also designed such that it can be used in harsh environmental conditions. 
     The drill  1  can be customised and optimised based on the desired application to provide different reciprocation and oscillation amplitudes just by changing the slope angle of the cylindrical cam grooves and the slope of the wedge angled surfaces, respectively. 
     Advantageously the drill  1  is also scalable. It can be envisaged that the drill  1  is used in a number of different applications. For example the drill  1  may be used in medical, oil and gas, space, terrestrial drilling and manufacturing applications, among others. 
     Many variants of the example embodiments described above and discussed below. The skilled person will be aware of further variants and modifications that may be made to the embodiments described herein. 
     In the above described embodiments the drill bit  2  comprises two halves, the first drill part  7  and the second drill part  8 . However, in alternative embodiments intended within the scope of the present disclosure, the first drill part  7  may be of a different size and/or shape to the second drill part  8 . 
     In the above described embodiments the drill bit  2  comprises two parts, the first drill part  7  and the second drill part  8 . However, in alternative embodiments intended within the scope of the present disclosure, the drill bit  2  comprises more than two parts configured to slide relative to each other. 
     In some embodiments the drill bit  2  is removable and replaceable. The drill  1  may be usage with a variety of different customised drill bits  2 . Advantageously if a drill bit  2  is damaged or if a different drill bit  2  is required to better suit the medium to be drilled, then the drill bit  2  can be changed. 
     In the above described embodiments the teeth  9  of the first drill part  7  are substantially symmetrical to the teeth  9  of the second drill part  8 . However, in alternative embodiments intended within the scope of the present disclosure, the teeth  9  of the first drill part  7  can be different to the teeth  9  of the second drill part  8 . In some embodiments only one of the first drill part  7  and the second drill part  8  comprises teeth  9 . 
     In the above described embodiments the first mating face  11  is configured to engage the second mating face  13  via an interlocking connection  15 . However, it can be appreciated that there are alternative known connection means which would enable the first part  7  to slide relative to the second part  8 . 
     In the above described embodiments the teeth  9  are spaced along a length of the first part  7  and the second part  8 . However, in alternative embodiments intended within the scope of the present disclosure, the teeth  9  are spaced along a portion of the first part  7  and/or the second part  8 . 
     In the above described embodiments the first mating face  11  comprises the track  17  and the second mating face  13  comprises the pin  16 . However, in alternative embodiments intended within the scope of the present disclosure, the second mating face  13  comprises the track  17  and the first mating face  11  comprises the pin  16 . In some embodiments both the first and second mating faces  11 ,  13  comprise both a track  17  and a pin  16 . 
     In the above described embodiments the head  20  and track  17  are rounded in shape. However, it can be appreciated that in alternative embodiments intended within the scope of the present disclosure, the head can be for example but not limited to, a cube, a disc, a cylinder, a cone or a hemisphere and fulfil the same purpose. 
     In the above described embodiments the head  20  is fully retained within the track  17 . However, in alternative embodiments intended within the scope of the present disclosure, the track  17  can merely receive and guide the pin  16  and not fully retain it. For example the pin  16  may not comprise a neck  21 , the pin  16  may comprise a ridge extending along a mating face  11 ,  13  of the first and/or second part  7 ,  8 , which is triangular in cross section. The track  17  may comprise a complimentary V-shaped notch to receive the triangular ridge. This configuration still prevents lateral movement or rotation of the first and second parts  7 ,  8  relative to each other. 
     In the above described embodiments the first angled surface  33  is symmetrical to the second angled surface  34 . However, in alternative embodiments intended within the scope of the present disclosure, the first angled surface  33  comprises a steeper or shallower angle of incline with respect to the central axis  28  of the drill  1 , than the second angled surface  34 . This is such that the drill bit  2  oscillates further in one direction than it does in the other. 
     In the above described embodiments in the neutral position the contact points  38  of the first and second members  22 ,  23  are at the same position along the angled surfaces  33 ,  34  of the wedge  32 . However, in alternative embodiments intended within the scope of the present disclosure the contact points  38  may be of different sizes, and/or the angled surfaces  33 ,  34  may be of different slopes. In these embodiments, in the neutral position the contact points  38  of the first and second members  22 ,  23  may not be at the same position along the angled surfaces  33 ,  34  of the wedge  32 . 
     In the above described embodiments the wedge  32  comprises a pair of angled surfaces. However, in alternative embodiments intended within the scope of the present disclosure, the drill  1  can be converted from a reciprocation and oscillation drill, to a reciprocation only mode by replacing the wedge  32  with a straight block and/or fixing the hinge joints or oscillating rod  6 . 
     In the above described embodiments the torsional spring axis is at the same point as the hinge axis  49 . However, in alternative embodiments intended within the scope of the present disclosure, the hinge axis  49  and/or the torsional spring axis may be provided at an alternative location. 
     In the above described embodiments the drill  1  comprises an openable cover  35  and an access cover  46 . However, in alternative embodiments intended within the scope of the present disclosure, the openable cover  35  and the access cover  46  can be the same component. 
     In the above described embodiments the guide member  40  is a sleeve to guide the first and second members  22 ,  23  as they reciprocate. However, in alternative embodiments intended within the scope of the present disclosure alternative guide members can be envisaged. For example, the guide member may be a pin and track connection wherein at least one of the outer shell of the stem  4  and the members  22 ,  23  comprises a protrusion and the other of the outer shell of the stem  4  and the members  22 ,  23  comprises a receiving portion, such as a groove. The protrusion is guided in the receiving portion to guide the reciprocal motion of the members  22 ,  23 . 
     In the above described embodiments the guide member  40  is fixed within the outer shell of the stem  4 . However, in alternative embodiments intended within the scope of the present disclosure the guide member  40  may be moveable. 
     It will be appreciated that the above described example embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present specification. 
     Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom, new claims may be formulated to cover any such features and/or combination of such features. 
     Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described example embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.