Buttonhole presser device and method of stitching buttonhole by using the same

A method for stitching a buttonhole having a length corresponding to a diameter of a button by measuring the diameter of the button and automatically switching a fabric feed direction on the basis of the measured diameter of the button by using a buttonhole presser device, the buttonhole presser device including a fabric presser unit attached to a presser bar of the zigzag sewing machine and having an opening that allows a needle to pass therethrough;

• a fabric feed frame unit including a start position detecting member and an immovable receiving portion that has a frictional contact surface that contacts one end of a button, the fabric feed frame unit being slidable relative to the fabric presser unit between a start position and an end position of the buttonhole;
• a button-diameter measuring unit including an end position detecting member and a movable receiving portion that has a frictional contact surface that contacts the other end of the button, the button-diameter measuring unit being configured to grip the button by being slid relative to the fabric feed frame unit;
• and a fixing unit that fixes the button-diameter measuring unit to the fabric feed frame unit, the method comprising:
• a step of gripping a button between the immovable receiving portion and the movable receiving portion by sliding the button-diameter measuring unit relative to the fabric feed frame unit;
• a step of fixing the button-diameter measuring unit to the fabric feed frame unit by using the fixing unit;
• and
• a step of removing, after the step of fixing has been finished, the button from the buttonhole presser device and of stitching a buttonhole.