Some technical topics are very straight forward and objective. Other issues I have handled are influenced by the perception and opinion of the users. One such issue is sewing machine vibration. Any machine that contains moving parts will have some level of vibration that is expected. The question is how much is too much. In this article, I will explain what causes vibration, try to dispel a few myths, and hopefully help you understand how to get a handle on the shakes.

Defining Vibration

    Now before we jump into the factors that contribute or reduce vibration, let us quickly define vibration. When something oscillates, or shakes, it moves back and forth at various speeds. The size of the motion is called amplitude. There is also the speed of the motion, and that is called frequency. These two aspects define how severe a sewing machine’s vibration is perceived. There are certain vibrations that are expected given the nature of how the machine is designed. These expected vibrations are then countered in the machine’s shape, weight, and other design attributes.

The Factors

    To put it in the simplest terms, the majority of vibrations in a sewing machine come from the motion of the needle bar moving up and down. But there are more factors to consider including:

Qualities of the sewing head
The needle bar
Balance of sewing Head

Qualities of the sewing head
       
    There are certain qualities of a machine that can be helpful to understand when dealing with vibration. First, one natural counter to machine vibration is the mass of the machine itself. The heavier the machine, the more vibration is absorbed in the mass of the object. I have seen examples of this when a customer - who is having vibration issues - will temporarily deal with the shakes by strapping wrist-weights to the machine handle bars. This is not ideal since it doesn’t solve the underlying issue, but it does illustrate the fact that the weight of an object reduces perceived vibration. Secondly, there is the concept of resonance. Think “tuning fork”. Every object has a certain inherent or natural frequency. If the oscillating force matches that natural frequency, the object will shake more - as with the tuning fork that shatters the glass. So what does that have to do with your machine? When running your machine, you will find certain speeds generate a noticeable increase in vibration, whereas the speeds just above and below do not. My best advice is to stay away from those speeds.

The needle bar
   
    Earlier, we covered the concept of amplitude. The needle bar motion is a great example of this. The distance that the needle bar travels is called the stroke of the needle bar. This is set by the design of the machine. Each stroke upward creates an energy that pushes up on the machine, and each stroke down creates a downward push. This is the amplitude of the machines primary cause of vibration. And of course, the speed at which you run the machine is the frequency. The designers of sewing machines have a way to counter this motion. Inside the head of the machine is a weight that moves in opposition to the stroke of the needle bar. This “counter” motion is meant to cancel out the wave of energy created by the needle bar and is aptly termed a “counter-weight”.

    Two things can easily upset this motion and increase the energy it generates - or in other words create more vibration. First, the needle bar is sliding through various parts, like bushings. Proper lubrication will allow the metal to slide quickly and effortlessly. A dry needle bar will scrap as much as slide, causing vibration and heat. I have worked with with machines that have cut into the bushings and even heated to a point that the bar seized up entirely. Needless to say, oiling the needle bar is important. In addition, the needle bar must be straight. Any side impact can create even the slightest bend which will increase vibration and may even stop the machine all together. Secondly, if the needle bar and counter-weight are not properly matched, the energy of the vibration will not be properly countered. This second issue is something for a qualified technician to evaluate. The first - proper oiling - is the paramount duty of the operator of industrial grade machines - like longarms - but for domestic machine, consult your manual.

Balance of the sewing head

    The best example of what role balance plays is to consider your clothes washing machine. As surely most have experienced, if a load of towels is set to one side your your washer tub, when the spin cycle hits - the machine can walk around the laundry room yelling all kinds nonsense. The same holds true with your sewing machine. As the waves of energy from the needle bar resonate through the head, any imbalance will allow the weight of the head to shake. Check the machine’s foundation. With domestic machines, the table should be flat and all the feet in firm contact with the table. With free-motion machines, the track system and wheels needs to be evenly in contact throughout tracking motion. If one wheel is high, or is the track bows away from the wheel - a noticeable increase in shaking can occur. Try moving the machine to the area with the most vibration. Then turn each wheel in place. If one is easier to move that the others, make adjustments until all the wheels feel about the same.

Lubrication

    The final consideration is lubrication. Earlier, we covered the importance of oiling the needle bar. The stroke of the bar must be unhindered. In addition, all oiling points are critical to smooth operation and vibration reduction. The drive shafts spin at high speeds within bushings and bearings. Also, gear teeth mesh together at high speeds. In some machines, these parts are impregnated or incased in oil and grease so that the operator does not need to handle the lubrication. Other machines require constant oiling to ensure the parts do not dry and begin grinding and scraping. The heat and vibration created by this is anything but good for the life of the machine. If you do follow your manual recommendation on lubrication, but find increased heat or noise to certain areas of the machines or even the motor - consult a qualified technician because that bearing or gear may be faulty and unable to get and maintain lubrication. This could lead to catastrophic failure.

Misconceptions

    Lets cover a few myths about vibration. The most common misconception is that if a table is not level the machine will vibrate more. It is not the levelness of the table, but the uniform balance of the machine that influences vibration. Another myth is that age will increase vibration. In truth, many machines will become smoother in operation over time. Care properly for the machine and can be with you for many years. Finally, although noise and vibration are often related, it is possible to have a very loud machine that operates smoothly. Any sudden and unusual noises should be investigated, but may be completely unrelated to machine vibration. Contact a technician for assistance.

    Vibration can be as little as a minor annoyance or a sign that your sewing machines is about to utterly fail. In most cases we find ourselves in that middle ground - annoyed at the shakes and the effect it has on sewing. Fortunately this is an issue that can often be helped when taking into account the inherent qualities of the sewing head, needle bar stroke, proper balance of the head, and adequate oiling. Remember that the size and speed of the vibration (amplitude and frequency) can be countered and minimized. Also keep in mind that all machinery has some expected vibration, especially at certain speeds. Armed with this understanding we will be more capable of getting a handle on the shakes.