An apparatus and method for managing bending and other applied forces that are exerted on a filament of thermoplastic with reinforcing fibers in a 3D printing system during the deposition process that is associated with the manufacturing of an object. The quality of the manufactured object is enhanced through a process that comprises i) applying torque to certain portions of the solid filament in a manner that is commensurate with the expected motions of the deposition head while depositing those portions, but only after ii) heating each portion to a sufficient temperature. A heating device and a twisting device act on the filament while it is moving toward the deposition point and while under the control of a controller that is operating according to a computer model of the object being manufactured.