AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT (Original) APPLICATION NO: LODGED: COMPLETE SPECIFICATION LODGED: ACCEPTED: r PUBLISHED: RELATED ART: NAME OF APPLICANT: Almonte Diamond Pty Ltd ACTUAL INVENTOR: John Wilder ADDRESS FOR SERVICE: LORD AND COMPANY, Patent and Trade Mark Attorneys, of 4 Douro Place, West Perth, Western Australia, 6005, AUSTRALIA. INVENTION TITLE: "ADJUSTABLE CORE SAW" The following Statement is a full description of this invention including the best method of performing it known to me/us: TITLE "ADJUSTABLE CORE SAW" 5 FIELD OF THE INVENTION The present invention relates to a core saw. DESCRIPTION OF PRIOR ART Geological sampling is a known means used to determine the quantities and qualities of 10 natural resources, such as petroleum and gas or metals and ores, contained well below a visible geological surface. A cylindrical core sample is obtained through known methods before a longitudinal dissection, using a core saw, is made on the core sample, for general convenience in viewing and analysis. The consistency of the material properties of a core sample are prone to be variable along the longitudinal length reflecting the differing 15 layers and structure of the sample. The existing prior art method of dissecting a core sample involves a core saw for use by the geological industry having a cutting blade located central to a longitudinal axis of a core guide means. These geological core samples are generally solid and hard, having 20 relatively good structural integrity along a length of the core sample. In the petroleum industry however the core samples are often taken in different locations and as such the structural integrity of the core sample is different. Generally a core sample from a petroleum location will be softer and of a lesser structural integrity than a core sample taken for use in the geological industry. The relative lack of structural integrity of a 2 petroleum core sample gives rise to problems during dissection of the core sample with a core saw. To overcome such problems a petroleum core sample is housed in a larger cylindrical member before the cylindrical member as a whole is dissected by known means such as for example using a core saw. This means that in use the effective cutting 5 area diameter is greater than an actual core sample diameter itself. In use core samples are not always dissected into even halves with other variations sometimes needed. Depending on the requirements in any particular case a core sample may have one or more longitudinal segment cuts made at various off centre positions. 10 Typically such variations will comprise a quarter segment cut or a third segment cut for example. It is known in the art to vary a cut performed on a core sample by offsetting the core sample with respect to a fixed cutting blade. To achieve this end it is known to hold a 15 core sample using an existing core sample holder during a cutting process within a core saw. A core sample is placed in a core sample holder and arranged to be aligned relative to the plane of a cutting blade using one or more core holder spacers. Existing spacers comprise a plurality of generally elongate geometric shapes which are arranged to provide a substantially 'V' shaped profile within the core sample holder. In use the 20 substantially 'V' shaped profile is used to locate and seat the core sample within the core sample holder and thus a controlled cut may be delivered to the core sample for a centred halving dissection or alternately an offset asymmetric dissection as required. The practice of housing a petroleum core sample within a larger cylindrical member 3 gives rise to problems in that the cylindrical member diameter is too large to be accommodated in an offset position by a standard core sample holder. As a result during a cutting operation the stability of the cylindrical member and the core sample held within is compromised. This leads to unpredictable cutting results potentially damaging 5 the core sample and the cutting means as well as making conditions dangerous for an operator. The present invention attempts to overcome at least in part the aforementioned disadvantages of previous methods and apparatus for dissecting petroleum industry core 10 samples. SUMMARY OF THE INVENTION In accordance with one aspect of the present invention there is provided a core saw for dissecting a core sample comprising a saw frame having a core guide means arranged 15 to support and convey the core sample to a core cutting means, wherein the core cutting means comprises means to adjust a cutting plane of a cutting blade with respect to core guide means. A method of using a core saw wherein a cutting plane of a cutting blade is adjusted in 20 order to achieve a substantially asymmetric dissection of a core sample. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 4 Figure 1 is a perspective view of a preferred embodiment of an adjustable core saw of the present invention; Figure 2 is an alternate upper perspective of the invention of Figure 1; and Figure 3a is a plan view of a preferred embodiment of a core cutting means of the 5 invention of Figure 1; Figure 3b is a perspective view of a preferred embodiment of a spacer member of the present invention; and Figure 3c is a side view of a preferred embodiment of the spacer member of Figure 3b. 10 DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, there is shown a core saw 10 having a saw frame 12 with an upper external surface 14 and a lower internal portion 16. The upper external surface 14 is arranged to provide an elongate channel 20 comprising a substantially U shaped portion 22 dimensioned to receive a core sample holder (not shown). The elongate channel 20 15 comprises a proximal loading portion 24 and a distal cutting portion 26. Further, the channel is provided with one or more longitudinal guide slots 28 thereby allowing communication between the channel 20 and the lower internal portion 16. 20 The saw frame 12 lower internal portion 16 is arranged to house a core guide means 30. The core guide means 30 comprises a drive chain 32 provided with a plurality of tangential guide fingers 34 spaced about the drive chain 32 and a core guide motor (not shown). The drive chain 32 is supported and driven by a plurality of sprockets 36 with at least one sprocket 36 coupled to the core guide motor by known means. 5 Preferably the core guide means 30 is housed in the saw frame 12 such that the drive chain 32 is longitudinally aligned with and positioned below the adjacent proximal and distal channel portions 24,26. The guide fingers 34 are dimensioned to protrude 5 upwardly through the channel 20 guide slots 28 and communicate with a core sample holder (not shown). The guide fingers 34 urge the core sample holder in a forward direction from the proximal loading portion 24 toward the distal cutting portion 26 of the channel 20, thereby bringing a loaded core sample into a dissecting cut relationship with a core cutting means 40. 10 The core cutting means 40 comprises at least a cutting blade 42 coupled to and driven by a cutting power means 50 by at least a drive shaft 45 and a bearing member 44. In a preferred embodiment of the present invention the core cutting means 40 cutting blade 42 is arranged to be mounted on a drive shaft 45 having a length and a distal end 62 15 and a proximal end 60 as seen in Figure 3a. The drive shaft 45 being in driven communication with the cutting drive means 50. The cutting blade 42 is arranged to be in communication with the distal portion 62 of the channel 20 and in planar alignment with the elongate dimension of the channel 20. 20 The cutting blade 42 is arranged and dimensioned to engage a core sample upon a core sample holder within the distal portion 26 of the channel 20 thereby providing a substantially longitudinal dissecting cut to the core sample. The cutting blade 42 is driven by the drive shaft 45 which is in turn driven by the cutting 6 power means 50. Preferably the cutting power means 50 is housed within the lower internal portion 16 of saw frame 12 and mounted therein by known means. In the preferred embodiment of the present invention as seen in Figure 2, the cutting power means 50 is coupled to the drive shaft by at least one belt 52 and a plurality of pulleys 5 54, whereby the belt 52 passes from the lower internal portion 16 to the external upper surface 14. Preferably the at least one cutting blade 42 is driven by a single cutting power means 50. It is acknowledged that the driving arrangement is configured with consideration given to 10 the respective cutting blade 42 diameter and running speed. In a preferred embodiment of the present invention a control panel (not shown) is positioned on the saw frame 12 in easy access of a machine operator such that the operator can control and/or vary the device 10 core guide means 30 and core cutting 15 means 40. It is envisaged the control panel includes at least emergency stop controls and conveyor direction reversal for safety in cleaning and removing obstructions as is known in the art. It is also to be understood that the core saw 10 may provide for the supply of coolant 20 and/or cutting agents to the at least one cutting blade 42 while a hood 58 is in an open and/or closed position, such supply may be controlled by the control panel 56. As seen in Figure 3a, 3b and 3c the core cutting means 40 further comprises a plurality of spacer members 46 each spacer member 46 having a predetermined thickness, t. In use, 7 one or more spacer members 46 are fitted to the drive shaft 45 between the cutting blade 42 and the drive shaft mounting 47. Use of the spacer members 46 has the effect of changing the cutting blade 42 position by moving the cutting blade 42 along the drive shaft, and thus changing the cutting plane with respect to the channel 20. 5 It is understood the plurality of spacer members 46 are not all of equal dimensions. Different spacer members 46 may be arranged to each have different thickness, t. In use a single spacer member or a combination of spacer members allows an operator to vary the cutting plane of the cutting blade 42. In this way an operator may adjust the core 10 saw 10 cutting blade 42 to deliver a customized asymmetrical longitudinal dissection upon a core sample. It is to be understood the adjustable core saw 10 of the present invention may be used in conjunction with existing core sample holder spacers. It is envisaged a plurality of spacer members 46 may be available in a variety differing 15 thicknesses. Preferably the spacer member 46 thickness t will be proportional to a core sample diameter or a cylindrical member in which the core sample may be mounted. The spacer member 46 may be made from any known suitable material such as stainless steel. 20 As seen in figures 3a and 3b the spacer members 46 will preferably be substantially disc shaped members having a central aperture 43 arranged to receive the drive shaft 45. Preferably each spacer member 46 comprises a locator means arranged to communicate 8 with an adjacent spacer member 46 or cutting blade 42 so as to orientate the spacer member 46. In a preferred embodiment of the present invention the locator means comprises an 5 outstanding button member 47 on at least a lateral side of the spacer member 46, and a complementary orifice 49 located on at least a side of the spacer member 46, wherein the orifice 49 is arranged to receive the button member 47 of an adjacent spacer member 46 such that in use the spacer members 46 and the cutting blade 42 are arranged to be in rotational agreement. 10 It is understood other locator means may be provided such as for example a drive shaft 45 having a key member (not shown) and spacer member 46 aperture 43 having a complementary key slot. 15 It is to be understood that a spacer member 46 may have any number of weight reduction features as are known in the art such as for example a contoured section 41. In use, a core sample (not shown) is manually placed into a standard core holder (not shown) preferably without the need for any core holder spacer members. The core holder 20 is then loaded in the proximal portion of channel 20 by a machine operator. Using the control panel the operator activates the machinery and the core holder is engaged by the tangential fingers 34 of the core guide means 30 and conveyed to the distal cutting portion 26 of channel 20 wherein the core sample comes into contact with the cutting blade 42. 9 When an off centre asymmetrical cut is desired an operator can remove the cutting blade 42 from the drive shaft 45 by removing at least one lock nut 48 by known means. The operator then fits the desired spacer member 46, or combinations of 5 spacer members 46 to the drive shaft 45 before refitting the cutting blade 42, aligning the locator means and tightening the lock nut 48. Following the adjustment, the cutting blade 42 now provides a cutting plane that can deliver a substantially asymmetric longitudinal dissecting cut upon a core sample mounted centrally in a standard core holder. 10 The core saw 10 is then operated in a known way to achieve the desired dissecting cut upon the core sample while the core sample is safely held in the core sample holder. Modifications and variations as would be apparent to a skilled addressee are deemed to 15 be within the scope of the present invention. 10