Thread is one of the critical items necessary for a sewing machine to function properly, yet the mechanisms which allow the thread to move through the machine are often overlooked. One of the most simple, yet critical, of these is the spool pin. Although they may vary in design and appearance from one machine to another, the modern sewing machine would not function without this small appendage.
The straightforward, but critical, purpose of a spool pin is to hold the spool of thread in the correct position for the thread feeding mechanisms to work properly. The spool pin must provide stability for the thread spool, but in itself does not provide direct tension for the thread being pulled from the spool. It allows the spool to turn as needed to unreel the thread but must keep the spool from being yanked off the machine by the force of the tension mechanisms.
Spool pins are most often plastic or metal pins, approximately the width of a pencil and ranging from 2 to 4 inches in length. Their design allows the spool of thread to spin freely. Spool pins can vary in several ways, including the direction in which they are pointed. Some machines have one or more spool pins pointed vertically, while others have a horizontally placed spool pin. Horizontal spool pins require a cap that slides onto the pin and holds the spool on the pin.
Spool pins are most frequently located either on top of the machine or near the back, on the right-hand side. This arrangement allows the spool of thread to stay out of the machine’s sewing mechanisms and permits easy access for the machine user. If a machine has more than one spool pin, the machine can most likely utilize more than one needle simultaneously.
Residue from the glue on thread spool labels can cause the spool pin to get sticky, inhibiting the free spinning movement of the spool. This can be removed with rubbing alcohol and a cotton ball. If the cap on a horizontal spool pin slips off too easily, the thread can easily fall off the machine. A new cap may be needed, or a rubber band can be slipped onto the pin, after the cap has been put in place, to keep the cap secure.
While both vertical and horizontal spool pins hold the thread in place adequately, some sewing machine users have personal preferences. Vertical spool pins tend to allow more movement from the spool, but this is compensated for by the tension mechanisms in the machine. When using a horizontal spool pin, it is best to place the spool’s notched end, which secures the tail of the thread, closest to the base of the pin. In this way the thread is less likely to inadvertently catch in the notch, preventing the proper feeding of the thread.