The full-discretization method recently proposed by Ding et al. (2010) [1] for the stability analysis of milling processes is shown to be related to the semi-discretization method in the sense that both methods approximate the original DDE by a series of ODEs. Rate of convergence estimates are provided for the full-discretization method, for the zeroth-order, and for the first-order semi-discretization methods. Computation times are analyzed and compared for low and high spindle speed domains. (C) 2010 Elsevier Ltd. All rights reserved.