A z-lift and leveling assembly for leveling a platen in a heated chamber of a 3D printer includes first, second, third, and fourth z-actuators in a rectangular configuration. Each z-actuator includes a linear drive configured to supply motion in the z-direction and a mounting bracket secured to the linear drive and configured to move with the linear drive in the z-direction. The assembly includes a set of four pin couplings each associated with one of the first, second, third and fourth z-actuators. Each pin coupling includes a pivot block secured to the mounting bracket with a first pivot pin forming a first pin joint between the mounting bracket and the pivot block, where the pivot block is configured to move relative to the mounting bracket about a first pivot axis of the first pivot pin. The pivot block is secured to the platen or an arm of the platen with a second pivot pin forming a second pin joint such that the pivot block and the platen move relative to each other about a second pivot axis. As the mounting bracket is moved, the pivot block moves relative to the mounting bracket about the first pivot axis and the pivot block moves relative to the platen about the second pivot axis such that a z-position of the platen can be manipulated to and maintained in a substantially level configuration in the z-direction though the independent manipulation of the first, second, third and fourth z-actuators and wherein the substantially level configuration can be maintained when the platen is incremented in the z-direction during printing of a part.