Every sewing machine has its own particular set of noises that you hear while using the various functions. When we operated a sewing machine dealership we chose Janome because they made some of the quietest machines on the market. What sounds they do make tends to stay relatively constant through the years of operation. Most owners become used to the normal sounds and are alerted whenever the sound changes. Those who do machine embroidery sometimes employ baby monitors so they can leave the room during a long embroidery. When the sound changes it’s a sign something is wrong and they can hopefully get back in time to prevent a tragedy.
The most common abnormal sound is the one that occurs when the thread is either out of the take-up lever, or there is no tension. Every stitch that wraps around the bobbin case will stay ender the needle plate. This creates the dreaded “bird’s nest” effect. The sound is a loud chunk-chunk-chunk as each stitch further inhibits the hook from making more. If the machine is stopped quickly, damage is usually limited to cutting off the excess thread and rethreading. Unfortunately if more than a few stitches are taken in this mode, the accumulated thread and powerful motor of the machine can lift the bobbin case out of its resting place in the hook race. That allows it to spin past the stopper. At that point it can be impaled by the hook, which usually stops the machine with a “Stopped for safety” message. It also will seriously damage the bobbin case, leaving a deep gouge on the bottom. Often when the bobbin case spins out it will be stabbed by the needle, often completely through the case. This type of damage can also damage the hook race itself, which leads to other noises.
After a bobbin case incident you may hear a rhythmic clicking as you sew. This click is often caused by a hole that was put through the bobbin case by the needle. It creates a small bump on the bottom of the case, and each stitch will catch briefly, causing the click. If the bobbin case is undamaged, a burr on the hook race can also cause a clicking. This type of damage is hard to see without a strong light and magnification. Your dealer should have the tools to remove minor burrs and scratches (#OILSTONE), but in severe cases a new hook race may be needed.
Bobbin rattling is a common complaint. As you sew the bobbin seems to jump around and rattle in the case. Often this is because the wrong bobbin is being used. Many people have old Singer class 66 bobbins inherited from old machines. They are the right diameter, but they are shorter than the standard Janome class 15 bobbin. That gives them extra room to bounce around. Another place that can induce rattles is the white plastic disc that is in the hook race under the bobbin case. A needle that is not tightened sufficiently can fall out and make nasty gouges in the disc. Every stitch has to pass over it, so if it is damaged it will cause a lot of jerking and bouncing of the bobbin. I’ve worked on machines where that disc was so damaged that it was in pieces. It’s inexpensive and easy to replace.
I’ve already mentioned the hook race as a noise source. If you have noise, but cannot find the source, it’s very likely to be the hook race. One really insidious problem that took me a long time to find is needle strikes on the rim of the hook race, the little “shelf” that the bobbin case rides on. If a needle hits that area it can make a pit with raised edges. Those edges act like a file, slowly grinding off a very fine dust from the bottom of the bobbin case. That dust causes a lot of extra friction. In sufficient quantities it can cause the machine to emit a very loud squawking sound. It can be silence for a short while with a drop of oil, though that can stain fabric, so use caution. In the long term the hook race must be polished or replaced. With this problem the bottom of the bobbin case will have a telltale white or gray line around the edge where the burr was grinding on it.
New embroidery machine owners sometimes complain about a squeaking while the machine is stitching out a design. This is usually not a problem, but is due to the belts of the embroidery mechanism settling in and adjusting to the parts they are attached to. In this problem the squeak is usually more prominent in one direction of embroidery than the other, for example left-right as opposed to front-back. It will diminish greatly over time as the parts settle in.
The last noise I will address is another tough-to-diagnose one. As you are sewing the machine makes a noise that sounds like a chirping bird. Inside the machine there is a pulley that is used to adjust the tension of the timing belt, which joins the upper shaft to the lower shaft for synchronous operation. Over a period of years and/or hard use, the bracket that the pulley is mounted on may slowly bend a little. This can cause the timing belt to drift away from its normal position so that it rubs on the bobbin winder clutch. That rubber-on-plastic rubbing makes the sound of a bird chirp. Your technician can fix it by replacing the pulley mounting bracket, though I have often been able to just bend the bracket a bit to make it line up again.
After you have had your machine long enough to know what it normally sounds like, you will notice if it starts to sound differently. In that case you should take it to your dealer, sooner rather than later. This post may serve as a guide to help you isolate the problem with the technician so you can restore it to its former silent glory.