The wavy stitch is caused by the thread size not matching the needle size. If you look at where the stitch interlocks, what we call "the bald head", those points do line up.
Thread, needle, and needle point, should match the weight of the fabric being sewn. For instance, mending cotton denim, a size 16 needle, which has a larger eye, and accepts a heavier (thicker) thread, universal tip. Stretch denim, a size 14 ballpoint needle. Sewing a quilt of cotton? A size 11 or 12 needle, sharp tip. Constructing a tailored dress shirt? Perhaps a size 10, topstitched with a size 8, and a fine thread.I
Needles become full with use. Change out every 6-8 hours of sewing. Oiling you machine should be done every 8 hours of sewing, too. Did you find the oil ports on the hand crank?
Last edited by WIChix; 03-05-2024 at 07:34 PM.