as shown in fig1 to 5 , a tool 1 according to the invention has a cup wheel - like tool member 2 serving as a tool support and having two diametrically facing identical cutting members 3 , which are identical and are the same with regards to their arrangement and alignment with respect to tool axis 4 . tool member 2 , which is axially symmetrical and namely cylindrical with respect to tool axis 4 has a circular circumferential wall 5 which , at the rear end , passes into an approximately identically thick front plate 6 , which is constructed as an annular disk through a bore 7 located in tool axis 4 . a cylindrical clamping 8 shaft located in tool axis 4 is fixed by a flange 9 held by screws to the outer face of front plate 6 , apart from the cutting members 3 , the tool member 2 carries a holding device 10 in the form of a cylindrical mandrel , whose rear end is inserted in centered manner in bore 7 and is e . g . also secured with flange 9 . the internal diameter or circumferential wall 5 is significantly larger than the external diameter of holding device 10 . each cutting member 3 has , as can in particular be gathered from fig4 and 5 , on a fixing shank 12 constructed as an elongated rectangular block , two identical cutting blades 11 in the longitudinal direction of shank 12 and projecting therefrom . the cutting blades are in each case symmetrical to the associated end face 13 of fixing shank 12 and formed e . g . in one piece with said end face 13 . the longitudinal axes of the cutting blades 11 coincide with the associated median axis of the fixing shank 12 . on their remote narrow sides , each of the cutting blades 11 has a linear cutting edge 14 , all the cutting edges also being identical . the two cutting edges 14 of each cuttingblade 11 are , according to fig2 at an acute angle 15 of e . g . approximately 22 ° to one another , as well as symmetrically on either side of the associated median plane 16 of cutting member 3 , which is a plane of symmetry of the cutting member . at the front or outer end 17 , each cutting blade 11 is provided with a flattened portion 18 in the form of a flank , which is rectangular to the median longitudinal plane 16 and in the vicinity thereof , the cutting edges 14 led up to said flattened portion 18 , have a distance from one another which is roughtly half as large as their maximum spacing . in cross - section or in longitudinal view , of fig5 each cutting blade 11 is approximately flat oval and namely on the inside 19 facing tool axis 4 and on the outside 20 remote from tool axis 4 is in each case bounded by a convex lateral face 21 or 22 . the radius of curvature of said lateral faces 21 , 22 in the particular longitudinal section of cutting blade 11 is larger than the associated spacing between the remote cutting edges 12 , so that lateral faces 21 , 22 pass into one another under an acute flank angle 23 of e . g . approximately 40 ° in the particular cutting edge 14 . instead of forming the flank faces of cutting edge 14 directly by the curved lateral faces 21 , 22 according to fig5 it is conceivable according to fig4 to form the flank faces 24 by planar , lamellar ground surfaces of lateral faces 21 , 22 . the length of each cutting blade 11 is smaller than that of the fixing shank 12 and the maximum cutting depth thereof is approximately of the same order of magnitude as the greatest width measured between cutting edges 14 , so that a very dimensionally stable cutting blade 11 is obtained . towards the outer end 17 , the thickness of each cutting blade 11 tapers in an acute flank angle 25 of e . g . approximately 20 °, the thickness in the vicinity of the end being roughtly a third of the thickness of the cutting blade 11 in the area up to which it can be used to give a maximum cutting depth . viewed in the longitudinal direction of cutting blade 11 , the fixing shaft 12 projects essentially on all sides over the cutting blades 11 , in such a way that in this view it is longitudinal and rectangular and its associated larger edge dimension is in the circumferential direction of tool 1 . as a result of the described construction of the particular cutting member , the advantages essential to the invention are obtained , namely in particular a very good cutting behaviour , a high cutting speed and long edge life periods , whilst avoiding vibrations of the cutting member and cutting blades 11 . as is further shown by fig1 to 5 , for receiving the particular cutting member 3 , the tool member 2 has on the outer periphery of circumferential wall 5 an adjustment slot 26 , which extends longitudinally from the front end face 27 of tool member 2 approximately up to the level of the inner face of front plate 6 . the width and depth of adjustment slot 26 are adapted to the fixing shank 12 in such a way that the latter fits with a slight slide or push fit , i . e . substantially in clearance - free manner , between the lateral faces 28 of the adjustment slot 26 and on engaging on its base surface 29 is arranged substantially flush in slot 26 , at least in the vicinity of end face 27 . relative to the working - rotation direction arrow 30 , adjacent to the trailing lateral face 28 of adjustment slot 26 and outside the same , a fixing screw 31 is inserted in a taphole on the outer circumference of tool member 2 and its relatively large diameter head 32 engages over the fixing shank 12 on the side remote from the base face 29 with an almost semicircular segment portion and with the latter presses the entire surface of the shank 12 in clamping manner against base face 29 . the diameter of head 32 roughly corresponds to the length of fixing shank 12 . head 32 engages over roughly half the width of fixing shank 12 and stands back with respect to the end face 27 of tool member 2 . as can in particular be gathered from fig2 the median longitudinal plane of the adjustment slot 26 coinciding with the median longitudinal plane 16 of the cutting member 3 is inclined with respect to tool axis 4 by an acute angle of approximately 10 ° in radial view of cutting member 3 , so that the end of adjustment slot 26 located in end face 27 trails with respect to its other closed end , with respect to the rotation direction arrow 30 . thus , in conjunction with the half of the angle 15 , by which the particular cutting edge 14 is inclined with respect to the median longitudinal plane 16 of cutting member 3 , a honing or drawing off angle 33 of approximately 20 ° is obtained , under which the cutting edge 14 intended for cutting use is pulled in inclined manner with respect to the tool body , so that each cutting blade 11 in cutting use acts as a honing knife . the cutting edge 14 on the same cutting blade 11 , but which is not in use , in the radial view of fig2 is approximately parallel to tool axis 4 . the particular cutting edge 14 intended for cutting use is oriented in such a way that only the cutting tip 34 formed by its outermost end and adjacent to the flattened portion 18 , in the rectangular view of the median plane of said cutting edge 14 according to fig2 is located in the axial plane of tool axis 4 at right angles to said median plane , whereas the following portions of cutting edge 14 are outside ( in front of ) said axial plane , in the rotation direction indicated by arrow 30 . the indicated median plane of cutting edge 14 is roughly a tangential plane 35 of tool 1 , which therefore intersects the axial plane 36 of tool axis 4 which is at right angles thereto in a line in which the cutting tip 34 is approximately located . as is further shown by fig4 the bottom surface 29 of adjustment slot 26 is inclined by a few degrees , e . g . approximately 3 ° relative to the tool axis in such a way that the median plane of the cutting blade 11 intended for cutting use and coinciding with the tangential plane 35 is inclined by a corresponding feed angle 37 with respect to the tool axis 4 . thus , in conjunction with the flank angle 25 for the lateral faces 21 , 22 of the cutting blade 11 , different setting angles 38 , 39 opening in the feed direction of arrow 40 are obtained . in the represented embodiment , the setting angle 38 of the inner lateral face 21 is smaller than the setting angle 39 of the outer lateral face 22 and is namely selected in such a way that a cutting burr formed on cutting appears in the working area of the outer lateral face 22 , i . e . on the edge of the hole to be made . as a result of a corresponding oppositely directed inclining , in which setting angle 39 is smaller than setting angle 38 , the cutting burr is formed on the hole disk . the smaller setting angle 38 can approach 0 ° and in the represented embodiment is 4 °, whereas the larger setting angle 39 is approximately 14 °. as a result of the described arrangement and alignment of the cutting edges 14 for cutting use , advantages which are essential to the invention are obtained , namely a stabilization of the cutting blades during cutting and a reduction of the cutting forces acting on the cutting edges . this is particularly the case if the clearance angle 41 of the flattened portion , flank 18 is approximately 10 °. a stop or support surface 42 is provided on the tool member 2 for the longitudinal alignment of the particular cutting member 3 with respect to tool member 2 . on said support surface 42 engages the particular cutting member 3 with the flank or flattened portion 18 of that cutting blade 11 , which is not intended for cutting use and is instead positioned flush in adjustment slot 26 . supporting surface 42 is formed by the circumferential surface of a cylindrical pin 43 , which is e . g . inserted by pressing into the base surface 29 of adjustment slot 26 , in the vicinity of its closed or rear end . supporting surface 42 is arranged in such a way that the fixing shank 12 projects slightly above the front end face 27 of tool member 2 . as is further shown by fig1 to 3 , holding device 10 projects over the front end 17 of cutting edge 14 by a multiple of the cutting depth thereof . at its front end , holding device 10 is provided with an end portion 44 , which tapers in frustum - like manner and whose rear end is spaced upstream of the front end of cutting edge 14 and which in the view according to fig2 and 3 , passes in slightly rounded manner into the cylindrical outer periphery of holding device 10 . the latter is intended for those cases in which the hole to be made is to be produced in the vicinity of an already existing smaller diameter hole . the external diameter of the holding device 10 is adapted to the internal diameter of the smaller hole in such a way that it engages therein with predetermined friction . in fig6 to 8 , the same parts are given the same reference numerals as in fig1 to 5 , but in each case index &# 34 ; a &# 34 ; is added . tool 1a according to fig6 to 8 differs from that of fig1 to 5 essentially in that the front end of the holding device 10a is tapered to form a sharp contact piercing point 44a . thus , prior to the start of cutting by cutting edges 14a , the holding device 10a can penetrate the area of the wall to be worked , which will subsequently be cut from said wall as the hole disk . holding device 10a is inserted with its wider diameter shank in replaceable manner in bore 7a of tool member 2a constructed in the form of a blind bore and which is formed by the inner circumference of circumferential wall 5a . on the rear end face , tool member 2a has a stepped clamping cylinder 8a . the adjustment slots 26a pass to the rear end face of the tool member 2a .