Sewing machines based on the Singer 15 design are often referred to as “standard domestic”, in particular their bobbins and needles. They were first introduced in 1895 with Singer model 15 and so are also known as “class 15”, remaining unchanged to this day.
Well, almost. 🙂 The bobbins remain indeed unchanged but the bobbin case got a few variations over the years.
The bobbin case has a characteristic arm that locks into a corresponding notch to keep the case stationary while the hook moves around it.
It points North-North-East or 1 o’clock, so this is the one-o’clock shuttle.
For a short time Singer used a mirror image of it – the eleven-o’clock shuttle. It appeared in models 15-89, 15-90 and 15-91, and then life got back to normal. 🙂
So we won’t talk about the weird eleven-o’clock shuttle.
Here are four nearly identical class 15 bobbin cases, from left to right:
- Singer straight stitch and Janome zig-zag side-facing,
- Bernina 4mm zig-zag forward-facing,
- Necchi zig-zag side-facing,
- everyone 5-7mm zig-zag forward-facing.
The slot started out small as the needle would only enter the bobbin case in one spot in a side-facing design. This is true both for straight stitch only machines and zig-zag because in a side-facing zig-zag mechanism the whole bobbin assembly moves left and right following the needle, so that the needle still enters the shuttle in the same spot.
Then Bernina and others turned it to face forward but with a narrow zig-zag there was still plenty of space for the needle to enter the slot even in its left-most and right-most position. When wider zig-zag arrived, the slot was widened accordingly in every forward-facing zig-zag machine.
But what is that weirdly shaped slot in Necchi’s bobbin case? Necchi used this with a side-facing shuttle but with a twin needle, for 3mm wide twin needles. I don’t see how such a shape would help, but if Necchi did it this way, this must help somehow. I have used other bobbin cases with sideways twin needle, and they work just as well. Hmm… Perhaps further testing is needed!
Have you noticed the little holes in the tips of Bernina’s and Necchi’s bobbin case fingers? They help to guide the thread but add a little extra tension. Necchi (side-facing) recommends passing the thread through the hole in the finger only when sewing with a twin needle. Bernina (forward-facing) recommends it only for sewing buttonholes. My own testing results are as yet inconclusive – I found that whether or not you should pass the thread through the hole in the finger depends more on the type of material you are sewing than on the type of stitch or number of needles that you are using. Basically, I would say that if you are having troubles with the regular threading (not through the hole), then you should try threading through the hole and see if it helps.
There are some other small differences between the bobbin cases of different makes, such as the shape of the hinges and of the spring ends, but I haven’t noticed any effect on stitch quality there. (We are of course not talking about poorly made bobbin cases where the thread is catching on the hinges or some such. Just bin those and get a new one.)
In conclusion, I think that the modern bobbin case with a wide slot is probably the most versatile and should work on all machines. Notice should in the previous sentence. You never know – some machines could be fussy!