Baby Lock Diana (BL480A) Instruction and Reference Guide - Manual (Page 57)

To Secure the Rolled Hem Thread Chain
Additional Information About Rolled Hemming
56
Hold the thread chain when you begin sewing to keep it from
curling into the seam.
Apply a small drop of liquid seam sealant to the end of the seam.
Allow to dry, then cut the chain close to the stitches.
Note: Test the liquid seam sealant for color fastness before use.
Turn the differential feed to 0.8 or 0.6 to eliminate puckering of
fine fabrics.
The minimum overedge stitch width that can be obtained for
rolled hemming is approximately 1.5 mm (1/16 inch) since the
cutting width cannot be set below 3.5 mm (9/64 inch).