of the base plane 5 and is apapted to support a sewing machine 8 actuated by an adapted drive element 9 the sewing machine 8 is therefore arranged overhanging from the base plane 5 with the arm which supports the operating head arranged perpendicular to the work side 5a and the needle 10 vertically aligned with said side 5a an upright 11 is rigidly associated with the bracket 7 and a pair of horizontally parallel arms upper 12 and lower 13 with respect to the bracket extend from said upright the arms 12 13 are provided at their ends with respective brackets 14 15 adapted to support related small shafts 16 17 which are both coaxial to the needle 10 of the sewing machine the small shaft 16 being rotatable while the small shaft 17 is fixed the small shaft 16 is rigidly associated with a frame 18 which is horizontally v shaped and provided at its ends with a pair of jacks 19 with a vertical axis which are adapted to actuate respective downwardly directed presser elements 20 the small shaft 16 rotatable on adapted bearings is controlled in its rotation in alternate directions by a gear composed of a pinion keyed to the small shaft 16 and of a rack provided on the stem of a double cylinder 21 rigidly associated with the bracket 14 when lowered the pressers 20 abut on an auxiliary work plane 22 rotatable about an axis defined by the small shaft 17 the rotatable plane 22.