the jaw member 14 about the axis 16 which is in turn produced by the lateral force of the pin 42 against the track 41 analytically the additional squeezing force may be conveniently resolved with respect to the axis 16 into a generally radial component exerting the fiber securing force and a circumferential component exerting the clockwise torque the counter torque produced by the tensioned spring 18 which initially maintains the jaw members in their comparatively unseparated relationship is overcome by the circumferential component when the fiber clamping members 26 and 28 securely clamp the waveguide 25 and additional manual squeezing force is applied to the handle members 34 and 36 the counter torque required to be overcome by the circumferential component may be made adjustable in order to adjust the amount of fiber clamping force exerted on the fiber waveguide by the fiber clamping members 26 and 28 a compression spring 70 may be mounted within a yoke 72 which is fixed to the backplate 11 the spring is compressed between the yoke 72 and the jaw member 14 the amount of force in the compression spring may be adjusted by means of an adjusting screw 73 with this arrangement the tension spring 18 and the compression spring 70 operate together to determine the amount of clamping force which must be applied by the squeezing of the handle members 34 and 36 before the jaw members 12 and 14 begin to separate the fiber clamping members 26 and 28 each include a member 30 and.