Additive manufacturing, or 3D printing, is a complex process that creates free-form geometric objects by sequentially placing material to construct an object, usually in a layer-by-layer process. One of the most widely used methods is Fused Deposition Modeling (FDM). FDM is used in many of the consumer-grade polymer 3D printers available today. While consumer grade machines are cheap and plentiful, they lack many of the features desired in a machine used for research purposes and are often closed-source platforms. Commercial-grade models are more expensive and are also usually closed-source platforms that do not offer flexibility for modifications often needed for research. The authors designed and fabricated a machine to be used as a test bed for research in the field of polymer FDM processes. The goal was to create a platform that tightly controls and/or monitors the FDM build parameters so that experiments can be repeated with a known accuracy. The platform offers closed loop position feedback, control of the hot end and bed temperature, and monitoring of environment temperature and humidity. Additionally, the platform is equipped with cameras and a mechanism for in-situ photogrammetry, creating a geometric record of the printing throughout the printing process. Through photogrammetry, backtracking and linking process parameters to observable geometric defects can be achieved. This paper focuses on the design of a novel mechanism for spinning the heated bed to allow for photogrammetric reconstruction of the printed part using a minimal number of cameras, as implemented on this platform.

翻译：增材制造，或称3D打印，是一种通过逐层堆积材料构建物体的复杂工艺，能够制造自由几何形状的物体。熔融沉积成型（FDM）是目前应用最广泛的技术之一，普遍应用于市面上的消费级聚合物3D打印机。尽管消费级设备价格低廉且数量众多，但它们缺乏科研所需的许多功能，且多为封闭平台。商用级设备价格更高，同样多为封闭平台，难以满足研究所需的改造灵活性。为此，作者设计并制造了一台专用于聚合物FDM工艺研究的实验平台，旨在构建一个能够精确控制和/或监测FDM制造参数的系统，以确保实验可在已知精度下复现。该平台具备闭环位置反馈、喷头与热床温度控制、环境温湿度监测等功能，并搭载了摄像系统与原位摄影测量机构，可在整个打印过程中持续记录几何形貌。通过摄影测量技术，能够追溯工艺参数与可观测几何缺陷之间的关联。本文重点阐述该平台上实现的一种创新性热床旋转机构设计，该设计能以最少的相机数量实现打印件的摄影测量重建。