The contact between tool and workpiece during nanomachining is a complicated phenomenon due to comparable tool edge radius, R, with cutting depth, a. This paper presents an investigation into the effects of tool edge radius on contact zone, chip formation mechanism, stagnation zone, tool forces and hydrostatic stress distributions. Molecular dynamics simulations of the nanometric cutting on single crystal copper were performed using EAM potential function with wide range from a/R = ∞ to tools with various rounded tip. Results showed that although at a/R ⩾ 1, both tool tip and rake edge participate in chip formation, at a/R