ABSTRACT Work on a standard turnkey CAD system has lead the author to develop a number of procedures for synthesising the motion of mechanisms. All derive from the concept of inserting the individual components into their own local space (or ‘box’). This can then be positioned within the machine space by attributing the appropriate six degrees-of-freedoms to describe the rigid body motions. Complex interacting assemblies can thus be generated. This paper concentrates on a recent development whereby the mechanism can be assembled at chosen instances (or ‘frames’) and the timing between them and their order is derived from the forcing conditions imposed throughout the event. The procedure generates, for each frame, a velocity diagram (scaled in terms of a primary unknown vector) and proceeds to balance the change in kinetic energy of the total system against the work performed by the external forces during each interval. This technique has been successfully applied to a number of problems, one of which is used to illustrate the technique in the paper.