Defects arising from the 3D printing process of continuous fiber-reinforced thermoplastic composites primarily hinder their overall performance. These defects particularly include twisting, folding, and breakage of the fiber bundle, which are induced by printing trajectory errors. This study presents a follow-up theory assumption to address such issues, elucidates the formation mechanism of printing trajectory errors, and examines the impact of key geometric parameters—trace curvature, nozzle diameter, and fiber bundle diameter—on these errors. An error model for printing trajectory is established, accompanied by the proposal of a trajectory error compensation method premised on maximum printable curvature. The presented case study uses CCFRF/PA as an exemplar; here, the printing layer height is 0.1~0.3 mm, the fiber bundle radius is 0.2 mm, and the printing speed is 600 mm/min. The maximum printing curvature, gauged by the printing trajectory of a clothoid, is found to be 0.416 mm⁻¹. Experimental results demonstrate that the error model provides accurate predictions of the printed trajectory error, particularly when the printed trajectory forms an obtuse angle. The average prediction deviations for line profile, deviation kurtosis, and deviation area ratio are 36.029%, 47.238%, and 2.045%, respectively. The error compensation effectively mitigates the defects of fiber bundle folding and twisting, while maintaining the printing trajectory error within minimal range. These results indicate that the proposed method substantially enhances the internal defects of 3D printed components and may potentially be applied to other continuous fiber printing types.

In this paper, an accurate error compensation method based on geometric parameter correction and process optimization is proposed for the problem of coupling error in a heavy-load longitudinal and transversal swing table (HLTST) under space constraints, which makes it difficult to control the position efficiently and accurately. The key geometric parameters of pitch and roll layers are determined according to the machining process and assembly relationship, and the kinematic model is modified to effectively reduce the impact of contour error on the system’s accuracy. A coupling error model is established and its transmission mechanism is analyzed to develop a positioning error compensation strategy. Numerical simulation is employed to examine the distribution law, sensitivity, and volatility of independent error and coupling error. This aids in optimizing the design of the table’s machining process by balancing machining accuracy and economy. After the identification of the error parameters, the error compensation model is verified using the uniform design experimentation. The experimental results demonstrate 96.94% and 65.63% reductions in absolute average errors for the pitch and roll angles, respectively, especially when the maximum positioning error under the maximum load condition is controlled within ±5%, which significantly enhances motion accuracy and robustness under complex working conditions. This provides theoretical support and practical guidance for real-world engineering applications.