Abstract: Spool case for sewing machines having devices for adjusting the braking spring of the thread spool. The case comprises a front wall and a cylindrical skirt portion defining a cavity or recess accommodating a thread spool; a flat spring for spool braking is secured internally on the front wall of the case and a screw acts upon the spring to adjust the braking pressure thereof. Between its securing location to the case and its contact location with the pressure adjusting screw, said braking spring has a projection or lug engaging with the case skirt.