Box forming machine with exchangable components

A machine (2) for performing operations on cardboard or the like blanks (26) (e.g. making cartons) has a plurality of separate components (8) arranged to operate on such blanks (26) as they are conveyed through the machine (2). The components (8) are securely mountable on a support member (14) which, with the components (8) mounted thereon, is arranged to be removably mounted on the machine (2). A number of support members with components set up for various sizes and configuration of blanks may be kept for use when required.