A robotic finger is provided that includes a base joint connected to a base member. The drill bit segments are connected via complementary threads in a spigot and socket fashion and the wrench serves to loosen adjacent segments with respect to one another in order to accommodate the insertion or removal of extension segments. A controller associated with a robot having an end effector attached to a robot arm thereto is turned off. The abutment block is received in a recess in the caliper housing, and is securely fastened to the caliper housing by a fastener. The physically separated charged particle stream is then removed from the system by use of an applied field and deflector. The invention is characterized in that the pump is of the piston type mobile in a body and defining the mixing chamber which emerges into the water reservoir via a non-return valve, and said pump also serves as additive proportioning tap.