Fused Filament Fabrication (FFF) systems are extrusion based technologies used to produce functional or near-functional parts from a variety of thermoplastic materials. For over 20 years Stratasys fused deposition modelers (FDM) dominated the extrusion market for additive manufacturing (AM). However, with the retirement of the original Scott Crump patent, a vibrant open-source development community spawned a new generation of personal fabrication machines and is exponentially driving interest in FFF technology and AM. Entrepreneurs and inventors around the globe are designing and fabricating new product designs without the limits of traditional manufacturing methods. However, as with all AM processes, variability in part strength continues to limit use in commercial markets. Development of accurate and repeatable methods for determining material strength in FFF produced parts is essential for mainstream manufacturing. This paper documents progress made on a continuing study to experimentally quantify the weld strength of filament welds as a function of nozzle temperature and print head speed. Test data indicate that weld strength is generally inversely proportional to print head speed with an inflection point at 15 millimeters per second, however effects were minimal with the observed range of strength changing only from 29.7 to 31.2 MPa. Weld strength was observed to be generally proportional to extrusion temperature, with an inflection point at 215 • C. Analysis of previous experimental data and examination of tested samples provide favorable insights and opportunities for additional and continuing investigation.