The legs of the Y straddle the edge of the fabric tape, and a set of dies then crimps the legs to the tape. A modern zipper machine can make stringers at a rate of 2000 teeth per minute.

To do this, bring the slider to the top of the zipper. You can use a seam ripper to remove fabric stitching if needed. Make sure you remove the zipper stop, if there is one, by cutting it with pliers.