Apparatus with adjustable circumference made up of a plurality of interconnected shoes

In an apparatus defining an outer circumference or an inner circumference suitable to serve as a forming surface or as a circumference-engaging surface, the improvement comprising

• frame means having a central axis,
• a plurality of shoes each of which includes an arcuate surface which in combination with the arcuate surfaces of others of the shoes collectively define a circumference,
• means for hingedly mounting each of said shoes to said frame means in circumferentially adjacent relationship about said central axis of said frame means, said shoes being radially displaceable inwardly and outwardly with respect to the central axis of said frame means such that said shoes move toward one another when said shoes are moved radially inwardly and away from one another when said shoes are moved radially outwardly,
• said means for hingedly mounting each of said shoes including elongated link means having an inboard end and an outboard end and means rotatably securing said link means to said frame means at a location along the length dimension of said link means intermediate its inboard and outboard ends,
• each of said shoes including first slot means
• defined in a first side margin thereof and second slot means defined in a second and opposite side margin thereof so that when said shoes are mounted in circumferentially adjacent relationship, the first slot means of each shoe faces the second slot means of a circumferentially adjacent shoe,
• a plurality of rigid rod means having first and second end portions, each of said rods having one of its end portions anchored in one of said first slot means of a first one of said plurality of shoes, and having its opposite end portion slidably received within a second slot means of a circumferentially adjacent one of said shoes to thereby interconnect and restrain said plurality of shoes to substantially identical degrees of rotation about their respective hinge axes.