  Parallel Kinematic Mechanisms (PKM) are interesting alternative designs for
machine tools. A design method based on velocity amplification factors analysis
is presented in this paper. The comparative study of two simple
two-degree-of-freedom PKM dedicated to machining applications is led through
this method: the common desired properties are the largest square Cartesian
workspace for given kinetostatic performances. The orientation and position of
the Cartesian workspace are chosen to avoid singularities and to produce the
best ratio between Cartesian workspace size and mechanism size. The machine
size of each resulting design is used as a comparative criterion.
