SINGER W102 - Manual (Page 30)

STITCH LENGTH
There are correct needle and thread stees for materials ...and there
IS
also a correct stitch length.
A simple rule to follow is (1) short stitches for light or sheer
materials, (2) medium stitch length for medium materials, and (3)
long stitches for heavy materials.
For best results-after selecting the correct thread and installing the
right needle^practice stitching on a sample oi the material by experi­
menting with the stitch length until you have found the length that
causes the thread to "blend” into the material.
The stitch length governs or controls the pace at which the material
moves under the presser foot, and when the correct length is longer
than average, more satisfactory work will be performed by operating
the machine at slower speeds.
Do not pull on the material, for it will cause uneven stitch lengths
-bend or break the needle-break the thread.
The sewing „.chine is des.gned the correc, an.„„n. of
thread in relation to the movement of the feed mechanism.