Particleboard (PB) is a widely used panel material for value-added applications. Unfortunately, machining problems can sometimes occur in practice that are time consuming and costly to resolve. The main reasons are the wide range of PB characteristics and excessive reliance on intuition and experience in PB use. Previous research on PB cutting has assumed plane isotropic properties and applied cutting theories from other materials for modeling. Unfortunately, the complex and non-uniform structure of PB at a microscopic scale is not accounted for in these approaches. A practical model requires that these factors be included. A PB cutting model is under development to increase the understanding of PB behaviour and guide the set-up and troubleshooting of machinery. The experimental results described in this report examine the effect of chip thickness and particle size on PB cutting behaviour. When the chip formation process is examined over a continuous range, PB displays unique cutting behaviour. First, the chip thickness can deviate from the theoretical value as a result of fractures that form in the PB below the tool path. These sporadic deviations also affect the chip thickness of subsequent cuts. Second, the chip formation process displays three distinct phases: Rub, Scrape and Cohesive Chip. No cutting occurs in the Rub phase. Third, the particle size also has a significant effect on PB cutting behaviour. The Rub and Scrape phases in chip formation tend to increase in duration with particle size while the Cohesive Chip phase tends to decrease. In addition, the cutting force and the amplitude of its fluctuation about an average tend to increase with the particle size.