Abstract: A method of determining one or more printer properties of an FFF printer, comprising the steps of: a) depositing a pattern (1) of one or more lines on a support (2) using the FFF printer; b) making an image of the deposited pattern (1) on the support (2) using an imaging device; c) analysing one or more geometric features of the pattern (1) in the image; and d) determining the one or more printer properties of the FFF printer based the one or more geometric features.

Abstract: The invention relates to an FFF printing system (100), the FFF printing system comprising a print head (105), a feeder (91;126) arranged to feed a filament (4) into the print head (105), and a container (801) for storing the filament on one or more filament spools (88). The system also comprises a prefeeder (81) arranged to feed the filament from the spools to the feeder (91;126), and a first flexible tube (D01;102;121) for guiding the filament (4). A filament path length measuring device (1) is arranged to detect a misalignment between the feeder and the prefeeder. Measurement signals are sent to a processing system to correct any misalignment.