Sewing machine accessory for circular sewing

A sewing machine accessory comprising:

• a plate for attaching to a sewing machine workbed and to be located below a needle, said plate including an opening formed therein, and including a guiding track formed therein, and
• a positioning device including a sliding member slidably engaged with said guiding track of said accessory plate, and a pointed member extended from said sliding member for engaging with a cloth material to be stitched and for forming of an arced stitch on the cloth material;
• wherein said sliding member includes a guide extended therefrom for slidably engaging with said guiding track of said plate and for guiding said sliding member to slide along said guiding track of said plate and to slide toward and away from said opening of said plate;
• wherein said guiding track is an elongated slot formed in said plate and defined between two flanges, and said guide includes a pair of grooves oppositely formed in said guide for slidably engaging with said flanges of said plate and for guiding said sliding member to slide along said guiding track of said plate;
• wherein said positioning device includes an anchoring member for engaging with said sliding member and for anchoring and retaining said sliding member to said plate at predetermined locations;
• wherein said sliding member includes a notch formed therein for engaging with said anchoring member which is engaged between said sliding member and said plate for anchoring and retaining said sliding member to said plate.