History
Needle Data (From 1963)
The most vital part of any sewing machine is the needle. Unfortunately, the needle is often overlooked when sewing difficulties are encountered and this oversight can make a major problem out of a minor one. Whenever an operator has sewing difficulties CHECK THE NEEDLE.
While a needle for fabric sewing may be regarded as a simple device, several characteristics in needle construction contribute to good sewing and high production. Understanding basic needle design can be very beneficial in selecting the proper needle when unusual sewing problems arise.
The points of most fabric needles are round or conical since this tends to spread material fibers without damage.
The pointed tip of most round point needles has a tiny blunt angle to strengthen the point against breakage or hooking. This is commonly called the set. If the needle point from the eye to the tip were ground at the same angle, the final tip would be an extremely long projection that would break or hook after a few penetrations of the fabric. By grinding the extreme tip at a blunt angle, hooking is minimized and there is less chance of the point catching fibers on the sewing thread which can cause thread breakage or fraying.
This blunt angle provides a serviceable needle point that will sew many thousands of stitches without hooking or blunting unless a foreign object is struck.
On many fabrics where the fibers are delicate and easily cut, a further refinement is the ball point. In this construction, the tip or set is ground like half of a ball. This ball point penetrates fragile materials by moving the fibers aside rather than piercing them.
The set or the ball point is approximately 10% of the needle size diameter. This is barely visible to the naked eye but it is the difference between sewing and not sewing.
The size of the eye is proportional to the diameter of the needle blade. Some special needles have undersized or oversized eyes for unusual conditions. The needle thread loop should form at right angles to the hook point or looper. Too large an eye will allow an unstable loop that may be missed by the hook point or looper.
An eye too small may prevent a loop from being formed. In all cases, the needle thread should pass freely through the eye but not loosely. The eye and the area around the eye must be very smooth and uniform in finish. Otherwise, excessive thread breakage will occur.
The area of the needle just above the eye on the loop-taking side is made either with a raised portion called a land or a notched-out portion called a spot or scarf. In both cases, the purpose is to present a better needle loop to the hook point or the looper. The land has the advantage of strengthening a small diameter needle, and it forces the needle loop out for easy loop-taking. The disadvantage to this construction is that on certain fabrics it causes a pinching effect on the thread as the land passes back and forth through the material.
The spot or scarf allows the look point or looper to be set close to the needle to ensure proper loop-taking. This construction offers more protection to the thread as it passes back and forth through the material. However, on very fine needles the removal of metal at this point usually makes a needle weaker and more subject to breakage. The major portion of needles used on fabrics is of the scarf type which seems to offer the best all-around compromise for good sewing conditions.
The grooves in the blade of a needle lead the needle thread down from the eyelets on the machine and provide protected channels for the thread as it is drawn through the material. Lockstitch needles are usually made with a long groove only. Most looper machine needles are made with a long groove on the front side and a short groove on the scarf side which allows the stitch to be pulled up.