of the latter can be adjusted by means of a regulating plunger 36 the fabric presser bar transmits a pre selected amount of force on the presser foot 24 which passes through the fabric and to the teeth of the feed dogs when the feed dogs are raised they cause simultaneous raising of the presser foot that results in a slight compression of the fabric presser spring 35 which increases the biasing force being applied to the presser foot the movable blade 15 is carried by a support arm 37 connected to the sleeve 34 and is caused to oscillate in the directions depicted by the indicating arrow z by means of an eccentric member 38 operatively connected therewith which is mounted on a rotatably driven shaft 39 the means which operatively connects the eccentric member 38 with the support arm 37 includes a connecting rod 40 fig2 having a pin 42 which interconnects it with one end of an arcuated arm 43 whose opposite end is fixed on the sleeve 34 so as to cause said sleeve and support arm to oscillate about the axis of the fabric presser bar 33 this driven shaft 39 and the eccentric member 38 are housed in the upper horizontal arm not shown of the sewing machine the support arm 37 has a u shaped bracket 44 forming that end opposite the end attached to the sleeve 34 and the arms of this bracket are identified by numerals 45 and 46 these arms 45 and 46 have bushings 47 and 48 respectively attached thereto in vertically aligned relation and serve to support a rod 49 for sliding movement therein the lower.