Every mechanism must be visualised as moving, where the different parts produce different loci for their different parts. When plotting the locus of a mechanism we divide the motion in temporal spaces and then plot the required loci. When a mechanism is driven by a crank, dividing time into 12 parts is very popular, but this does not apply to all mechanisms. In a glisette mechanism, for example, one is free to plot as many instances of the movement as needed.
