Design and Development of a Rotating Nozzle for Large-Scale Construction 3D Printer

This study focuses on the design and control system of a rotating nozzle for 3D construction printers. The development of a rotating nozzle is motivated by the need to enhance control over extrusion direction and material alignment, thereby improving the mechanical performance of printed structures by the use of non-circular nozzles. The typical 3D construction printer is equipped only with a stationary circular nozzle, which prevents the use of a non-circular nozzle due to the printer’s lack of a rotational mechanical system. This, in turn, limits the opportunity to enhance mechanical properties such as tensile and compressive strengths effectively. The proposed design is developed through computer-aided design (CAD) software, and the printer’s configuration is adjusted for integration of the rotational mechanism’s control system. This design includes a full description of the rotational mechanism and integration steps for the 3D printer. Besides the main motor of the 3D printer, an additional motor is installed next to the nozzle and controlled by a new axis (parameter), which is added into the G-code. A new axis, called “U”, is responsible for the rotation of the nozzle itself. For the development of this axis design, the cosine law is applied. The calculation is based on the three consecutive points in the G-code to obtain an accurate degree of rotation for the nozzle. The effectiveness of the system was confirmed by evaluating the compressive strength depending on printhead type. Based on testing results, one trowel printhead had the highest flexural strength of 5 MPa, and a trapezoidal printhead with teeth had the highest compressive strength of 8 MPa, compared to a circular default nozzle head with 6 MPa and 2 MPa for compressive and flexural strengths, respectively. The new optimized nozzle design is implemented in existing 3D printers, which allows it not only to develop its capability in the printing process but also to make sustainable contributions in the 3D construction industry.