The reduction of the straw length in the threshing section of a combine harvester is considered to be an important indicator for the crop processing quality. An aggressive threshing action or discontinuous flow of the crop material invokes high impact and friction forces on the crop. This breaks up the straw, resulting in a swath of low volume which complicates the subsequent baling process. Therefore, the impact of the settings of the threshing process on the straw quality, expressed in terms of the swath volume has been assessed in this study. An experimental design involving different combinations of machine settings has been applied and for each of these setting combinations the resulting swaths have been scanned with a LiDaR (Light Detection and Ranging)-sensor. By a backward stepwise regression a quadratic relation between the concave clearance and rotor speed setting and the swath height was found (R2 = 0.79). All terms in the model were significant (p value of F-statistic <0.05). The observed relation between machine parameters and straw quality is interpreted as a combination of forces on the crop and residence time of the crop in the threshing and separation section. Insight in the interaction of crop and machine is gained that could be a useful input for optimizing the settings of the threshing and separation section.