The noise during sewing usually comes from the hook. The “standard domestic” vertical oscillating hook is the most commonly used hook of them all, it was introduced in the late 19th century in Singer model 15.
The hook is pushed about in its race by the driver that usually has a spring on it.
This is an oscillating hook, so the driver swings back and forth, bumping into the hook at the ends, and this is what makes the noise. The amount of space between the tip of the driver spring and the hook determines the amount of noise the machine makes. The smaller the space, the less noise is produced.
Excessive noise either indicates a problem (hook needs oiling, something is stuck in it, the bobbin doesn’t spin properly, etc.), or poor quality of manufacture (it is too loose and the shuttle is wobbling about). In both cases things can often be improved!
The first thing to do, then, is to see whether there is a problem.
Step 1: Clean, polish and oil. Open the hook assembly and remove the hook. You can now clean everything in it and oil the race. Just a drop of oil on the “rail” is enough, but it needs to be done frequently. A good rule of thumb is to oil the race every time you wind a bobbin.
Polishing is only required if the surface is not smooth, check both the hook and the race. There could be dirt build-up that is stuck and needs scraping off, or it could have been damaged by debries or by a broken needle as it happened to my Dragonfly.
Step 2: Adjust the spring. If the hook is still noisy, the driver spring may be too flat. It is held in place by two screws, so if you manage to unscrew them, you can adjust or replace the spring for a tighter fit with the hook.
Some hook drivers don’t have a spring. Look at this spring-less driver in a 1954 Frister & Rossmann machine made by Vesta (or Gritzner & Kohler, may be? see comments below):
The hook fits quite tightly with that driver, so the machine is not exceptionally noisy. The space between the driver and the hook must be large enough for the upper thread to pass through it. If you want the machine to be able to handle thicker top stitch thread, you have to leave a sizable gap there, and this is where a spring is so beneficial. However, a solid driver certainly works.
Step 3: Modify the driver. When my Harris Automatic arrived, it was making a lot of noise during sewing. An investigation revealed that the hook driver had a broken spring which made the hook wobble.
The obvious course of action was to replace the broken spring, but I could not undo the screws.
There must be another way.
All I needed was a spacer to fill the gap between the driver and the hook, so I decided to solder some tin onto it.
It worked, but had to be filed and polished to a very smooth finish, otherwise the thread was getting caught on it on the way out.
The tip of the driver has to be moulded quite carefully so that the thread would slip off it properly. It was only weeks later that I came across that spring-less driver by Vesta, and that driver’s shape is better than mine. I should improve my sculpting on Harris. :-)
Another idea would be to take a new spring, break it just above the screw hole where Harris’ spring was broken, and solder on the spring tip instead of a solid bump. Might work better, and is certainly something to try.
The bottom line is: do whatever is necessary to get your machine sewing again!