Abstract: Apparatus for assembling a core for wound sheet material, comprising a tube, a first end member, and a second end member; the apparatus comprising a base, a first chuck for insertion in the first end member, a second chuck for insertion in the second end member, a ram for applying axial pressure such that the first end member is forced into the first end of the tube and the second end member is forced into a second end of the tube, drill devices for drilling fixing apertures, and a monitor device for sensing ambient temperature and enabling the length of the core to be measured at the time of the assembly of the core in the ambient temperature so that the length of the core falls in temperature and length parameters set for subsequent winding of the sheet material on the core.