We show the existence of a subcritical Hopf bifurcation in the delay-differ
ential equation model of the so-called regenerative machine tool vibration.
The calculation is based on the reduction of the infinite-dimensional prob
lem to a two-dimensional center manifold. Due to the special algebraic stru
cture of the delayed terms in the nonlinear part of the equation, the compu
tation results in simple analytical formulas. Numerical simulations gave ex
cellent agreement with the results.