Abstract: A precision pumping device for aspirating and dispensing different volumes of fluid is presented. The precision pumping device comprises a housing with integral anti-rotation guides, a stepper motor which drives a fine pitch lead screw, a coupling for linking the piston to the leadscrew, an anti-backlash leadscrew follower, a split hub clamp nut, and a nut for securing the chamber to the housing. A seal is provided which seals around the piston and against the chamber, as is an o-ring that is set into a groove in the chamber and seals against a flange of the seal. The precision pumping device further includes a piston and a chamber for receiving at least a portion of the piston therein. The piston and chamber are of different sizes for aspirating and dispensing different volumes of fluid. The chamber can include a single port or multiple ports.