An injection molding machine includes a base, a stationary platen fixed to the base for holding a first mold section, and a moving platen for holding a second mold section. The moving platen is slidably supported on a platen slide surface fixed to the base and moveable along a machine axis between a mold closed position, in which the moving platen is drawn towards the stationary platen, and a maximum daylight position, in which the moveable platen is spaced axially apart from the stationary platen by a platen opening. The machine further includes a carriage support structure slidably supporting a stack mold carriage for holding a mold center section. The stack mold carriage is translatable parallel to the machine axis between a carriage advanced position and a carriage retracted position spaced axially apart from the carriage advanced position by a carriage stroke length. The carriage support structure includes a pair of beams removably fixed relative to the base, the beams extending parallel to the machine axis and spaced apart from each other by a lateral spacing, each beam having a beam length that is less than the platen opening and greater than the carriage stroke length.