3D printing using material extrusion is increasingly considered as a means to produce not just prototypes, but also final parts. This has accelerated research of the strength of printed parts. With 1461 printed tensile bars tested, this study adds a systematic investigation to the existing body of knowledge, assessing the influence of layer height, print speed, nozzle temperature, object orientation, and fill density on tensile strength across five Ultimaker 2’s, and a few competitors. The large number of test bars tested allowed for a high data density of the test matrix; providing enough statistical depth as the variance within printed results was found to be high. PLA (polylactic acid) has been chosen as the main tested material, as it is found to be the most popular material for desktop printing. Its standard tensile properties were established by injection moulding tensile bars made from shredded filament. Via analysis of variance (ANOVA) the influence of the print parameters has been ranked as follows: fill density, print speed, layer height, orientation, and temperature.