Kinematic error modeling and error compensation of desktop 3D printer

Abstract

Desktop 3D printers have revolutionized how designers and makers prototype and manufacture certain products. Highly popular fuse deposition modeling (FDM) desktop printers have enabled a shift to low-cost consumer goods markets, through reduced capital equipment investment and consumable material costs. However, with this drive to reduce costs, the computer numerical control (CNC) systems implemented in FDM printers are often compromised by poor accuracy and contouring errors. This condition is most critical as users begin to use 3D-printed components in load-bearing applications or to perform mechanical functions. Improved methods of low-cost 3D printer calibration are needed before their open-design potential can be realized in applications, including 3D-printed orthotics and prosthetics. This paper applies methodologies associated with high-precision CNC machining systems, namely, kinematic error modeling and compensation coupled with standardized test methods from ISO230-4, such as the ballbar for kinematic and dynamic error measurements, to examine the influence and feasibility for use on low-cost CNC/3D printing platforms. Recently, the U.S. Food and Drug Administration's “Technical considerations for additive manufactured medical devices” highlighted the need to develop standards specific to additive manufacturing in regulated manufacturing environments. This paper shows the benefits of the methods described within ISO230-4 for error assessment, alongside applying kinematic error modeling and compensation to the popular kinematic configuration of an Ultimaker 3D printer. A Renishaw ballbar QC10 is used to quantify the Ultimaker's errors and thereby populate the error model. This method quantifies machine errors and populates these in a mathematical model of the CNC system. Then, a post-processor can be used to compensate the printing code. Subsequently, the ballbar is used to demonstrate the dramatic impact of the error compensation model on the accuracy and contouring of the Ultimaker printer with 58% reduction in overall circularity error and 90% reduction in squareness error. Keywords: 3D printing accuracy, Kinematic error modeling, Kinematic error compensation, Ballbar, FDM 3D printing, ISO230-4