an upright 60 said upright 60 directing the carriage support plate 12 towards its upper plane 24 via an elbow 61 disposed upon the upper plane 24 of the carriage support plate 12 is a threaded aperture 62 which cooperates with a threaded device 63 such as a screw to restrain the protective dust shield 13 in its required position still referring to fig3 it can be seen that the threaded aperture 50 cooperates with a threaded device 64 such as a stud and passing through an aperture 65 provided in the carriage support plate post 31 to form the restraining member of the carriage support plate post 31 continuing with fig3 it can be seen that the stabilization plate 7 is provided with a number of threaded apertures 67 which apertures 67 cooperate with a number of adjustable retaining screws 47 to provide an adjustable means of restraint such that the stabilization plate conforms to a critical perpendicularity to the central axis 69 of the spindle and motor assembly 5 and having a number of threaded locking means 68 such as nuts which nuts cooperate with the adjustable retaining screws 47 to insure said critical perpendicularity to the central axis of the spindle and motor assembly 5 still referring to fig3 it can be seen that a tachometer disc 70 which tachometer disc 70 is shown securely attached to the spindle and motor assembly 5 said tachometer disc 70 is utilizeable in generating an electrical signal indicative of the spindle speed at any given moment said electrical signal providing an accurate representation to servo means such that the servo means will maintain the spindle speed within a critical limit of a desired speed of rotation now referring to fig4 a detailed.