Using even the most basic sewing machine, you can achieve interesting surface effects. This looks like a fine thread laid on the surface of your fabric ideal for outlining or fine lettering.
Tighten the top thread tension, thus pulling the bobbin thread through the fabric, thus showing both threads on the top surface of the fabric.
Set the stitch length to the minimum so that the top thread is completely covered by the bottom thread when stitching thus making the appearance of a cord lying on the surface of the fabric.
Try working layers of spirals, using tonal shades. This creates a wonderful texture – ideal for landscape details.
Try using thicker top threads such as a Anchor Pearl 12’s – these will automatically tighten the top tension, due to their relative thickness in relation to the gap in between the tension wheels (adjust needle size to suit such as 100 or 110).
Try working more over one spot to create raised bobbles in the stitching.
Try working with thicker bobbin threads on a looser woven fabric.
Try working with a fine, uneven thread on the bobbin to create areas of thick and thin.