the preferred embodiment of the invention is disclosed in fig1 and 2 . referring to these figures , the chuck body is generally indicated at 10 ; the collet is generally indicated at 12 ; and the workpiece which is shown in broken lines is generally indicated at 14 . the chuck body is generally of conventional construction and has an open top , cylindrical sidewalls 9 and 11 and a bottom having a central opening 16 therethrough . the top edge of the chuck body has a plurality of annularly spaced slots or recesses 18 formed therethrough , there being three of such slots in the embodiment illustrated . annular inserts or dogs 20 are received within such slots and are suitably secured to the top edge of the chuck body by screws , for example . a workstop 22 is formed integral with the top of each of the inserts 20 for supporting the over - edge of the workpiece 14 , as shown in fig1 . the body 10 is also formed with a plurality of annularly spaced openings 24 through the sidewalls so that the interior is accessible for chip removal . in this embodiment the chuck body 10 is shown as a single member and may be formed of conventional material used for that purpose . the chuck collet 12 comprises an annular base 26 having its peripheral surface bearing against the surface 11 as shown in fig1 ; a plurality of chuck jaws 28 , and there being three in the embodiment illustrated ; and interconnecting members between the chuck jaws 28 and the base 26 which in this embodiment are in the form of spring steel or spring tempered steel rods 30 . the materials selected for the rods have such properties as to be stiff enough to hold the jaws away from the workpiece for ready insertion of the workpiece between the jaws , be flexible enough to accommodate the rough chip of the workpiece and still permit it proper clamping , and be strong enough to handle the high axial forces necessary to aim the jaws into clamping configurations . the rods 30 are of such length as to give the required movement between the clamp and unclamp positions consistent with the other required functions of the rods . as best seen in fig2 at least three rods 30 are connected to each jaw 28 , with all of the rods connected to a single jaw intersecting base 26 along an arcuate path . the open inner edge of the body 10 adjacent the segments 28 and the outer surfaces of the segments 28 are provided with cooperative tapered surfaces 32 and 33 respectively as so that upon relative axial movements of the chuck body and chuck collet the segments 28 will be moved toward and away from workpiece to grip and release the workpiece . as shown in fig1 the periphery 27 of the annular base 26 of the collet 12 is in slidable engagement with the adjacent annular surface 11 of the chuck body 10 , in the usual way . the base 26 is provided with a central opening for receiving a coupling 34 which may be connected in the usual way to a draw screw for effecting the clamping and unclamping of the collet . the collet segments 28 may be provided with serrations 36 or other means , such as carbide inserts , may be used if desired . as described above , the collet segments may be made of a material of selected hardness or the entire jaw segment may be made of carbide . it will be understood that since the collet 12 is not constructed as a single unit but is constructed of separate elements 26 , 28 and 30 , the materials for these elements may be selected by the designer to give optimum functional results under the most economic conditions . it will also be observed that the turning torque is taken by the inserts or dogs 20 on the chuck body which engage the jaws 28 so that the interconnecting rods 30 won &# 39 ; t take the torque . it is also pointed out that for roughing work three jaws as illustrated are preferable ; but for finish work more jaws may be found to be desirable and such adaptations are obvious to one skilled in the art in light of the teachings of this disclosure . another modification of the invention is disclosed in connection with fig3 and 4 . this modification is particularly adapted for the support of a workpiece of substantial length on the outside of the chuck collet and particularly for supporting a workpiece having substantial variations in its external contour along its length as well as having different internal diameters . the clutch body which forms the support means for the collet is generally indicated at 10 &# 39 ; and is formed of parts 38 and 44 . the clutch collet is indicated at 12 &# 39 ;, and the workpiece is indicated at broken lines at 14 &# 39 ;. it will be seen that the workpiece 14 &# 39 ; has different internal diameters along its length so that the collet 12 &# 39 ; is modified to grip the internal surfaces of the workpiece and accommodate the differences in internal diameters . the chuck collet 12 &# 39 ; comprises axially spaced upper jaw segments 28 &# 39 ; and lower segments 29 viewing fig3 . the segments 28 &# 39 ; and 29 are interconnected by rods 30 &# 39 ; which are the same functionally as the interconnected rods 30 in the previously described embodiment . observing fig4 it will be seen that the jaws 28 &# 39 ; and 29 are annularly staggered in an overlying relationship and connected by such rods 30 &# 39 ; in such staggered relationship . it will also be seen by observing fig3 and 4 that the workpiece 14 &# 39 ; is engaged by the outer cylindrical surfaces of the jaws 28 &# 39 ; and 29 and that the o . d . of the jaw segments 29 are larger than 28 &# 39 ; so as to grip the two different internal diameters of the workpiece 14 &# 39 ;. the clutch body member 10 &# 39 ; comprises a base 38 having a central axial projection 40 . the body 10 &# 39 ; is provided with an annular tapered surface 42 which is adapted to cooperate with similarly tapered adjacent surfaces 43 on the inner face of the jaw segments 29 . the elongated member 44 is disposed within the central opening 46 of the base 38 and has an integral upper annular portion 48 formed with a tapered surface 50 which is adapted to engage a similarly tapered surface 51 on the inner faces of the upper jaw segments 28 &# 39 ;. the member 44 is pulled into the body 10 &# 39 ; by suitable means and the relative axial movement effects clamping of the jaws 28 &# 39 ; and 29 by forcing them outwardly against the adjacent inner diameters of the workpiece 14 &# 39 ; due to the interaction of the cam surfaces 42 and 50 . the clamping jaws may be held in that position by a set screw 52 . again , it is pointed out that in this embodiment the elements 28 &# 39 ;, 29 and 30 &# 39 ; forming the collet are separate and have the advantage of material selectibility as described above . referring to fig5 another modified structure is illustrated in which leaf spring elements 54 are employed for interconnecting the central base 26 and the collet jaws 28 . this leaf spring is relatively narrow as shown in fig6 and is designed to have substantially the same functional characteristics as the rods 30 . the leaf spring 54 would , in effect , be substitutes for the rods 30 as shown in fig1 and 2 . referring to fig7 a further modification of interconnecting means is illustrated in which the collet base 26 and the jaws 28 are interconnected by a single flat spring leaf member 56 which may be designed by its length , thickness and transverse width to give it the same desired flexibility and strength characteristic as the plurality of rods as disclosed in the previous embodiment .