In this paper, the mechanical load of boring tools is investigated. Derived are the equations for defining the deformations caused by the radial and axial components of the cutting force. Also presented is a function for the total deformation of the tool. Conducted are experiments for defining the mechanical deformations of boring tools caused by the radial component of the cutting force. As a result of the experiments the share of the axial and radial components of the cutting force in the total deformation is defined.