October 20, 2023
Published on  Updated on  

Sewing machines are an integral part of the world of sewing and textiles. They help precisely and efficiently create intricate patterns, embroideries, and designs. However, it is not just the sewing machine that makes the magic happen; it is also the small but essential parts that make up the machine. One such part is the sewing machine bobbin case. In this blog, we will explore the differences between oscillating, rotary, and top-loading bobbin cases on sewing machines, specifically in replacement cases, class 15 bobbins, and Singer bobbin cases.


The sewing machine bobbin case is a small metal or plastic part of the sewing machine that holds the bobbin, which is a small spool of thread that sits underneath the sewing machine needle. The bobbin case, sometimes referred to as a bobbin holder, helps ensure that the bobbin thread is in the correct position to interlock with the upper line, creating a tight, even stitch. The entire bottom-thread area that houses your bobbin case is called the "hook system".

When it comes to the type of bobbin case, there are three main types: oscillating, rotary, and top-loading.

Need more info? Check out our Know Your Bobbin Cases tutorial on YouTube!


The oscillating hook is one of the oldest types of bobbin cases and is often found in vintage and entry-level sewing machines. In an oscillating case, the bobbin sits in a vertical position, and the sewing machine needle pulls up the thread and interlocks with the upper thread to create a stitch by rocking the hook back and forth.

Race Hook Unit, Bernette #5020601124
Oscillating Hook Bobbin Case - Bernette

One of the benefits of oscillating hooks is that they are generally straightforward to use and easy to thread. However, they do have some limitations. Because the bobbin sits vertically, it is more prone to jamming or getting stuck, especially if the thread is not properly wound around the bobbin. Additionally, the oscillating system can be more challenging to clean and maintain than other types of bobbin cases.


The rotary bobbin case is a common type of front-loading bobbin case that is often found in modern industrial sewing machines. In a rotary hook, the bobbin sits vertically as the hook makes a FULL rotation around it. This differs from an oscillating hook, which rocks back and forth.

Rotary hook - consew
Industrial Rotary Hook - Consew

One of the main benefits of a rotary bobbin case is that it is less prone to jamming than an oscillating hook. Because the hook makes full rotations, it runs smoother and is less likely to get stuck or tangled. This is why it's offended seen in industrial, semi-industrial, and quality quilting machines such as the Babylock Accomplish 2 or the JUKI TL-2010Q.


The top-loading bobbin case is the most common type of lower-thread system when it comes to domestic sewing machines. In a top-loading bobbin case, the bobbin sits horizontally. Top-loading bobbin cases and the bobbins that go with them are often made of plastic. They are user-friendly, easy to use, and replacement parts can often be located.

Top-loading bobbin case Janome
Top-Loading Bobbin Case - Janome

Another benefit of the top-loading bobbin is that it remains visible after being loaded into the machine, allowing you to check the thread level and replace the bobbin as needed.


Vintage Shuttle-Comb Style Bobbin Case + Bobbins - Singer

The vintage shuttle comb is a rare type of lower-thread system that was used in old treadle machines. They're shaped like a bullet of lipstick and have unusual bobbins to match. Surprisingly, these vintage sewing machine parts are still manufactured and used by treadle sewing machine enthusiasts!

Need parts for your vintage Singer Treadle Sewing Machine? Search by model number here!


In conclusion, understanding the differences between oscillating, rotary, and top-loading bobbin cases is crucial for any sewing enthusiast or professional. Each type of bobbin hook has its own advantages and considerations when it comes to replacement bobbin cases, class 15 bobbins, and Singer bobbin cases.

Regardless of the type of sewing machine you choose, it is important to ensure proper maintenance and threading techniques to avoid issues such as thread jams, tangles, or skipped stitches. Consult your sewing machine's manual for specific instructions on lower thread area care and maintenance.

At Sewing Parts Online, we understand the significance of selecting the right bobbin case for your sewing machine. We offer a wide range of replacement parts, including options for class 15 bobbins and Singer sewing machines. Our knowledgeable team is available to assist you in finding the perfect bobbin case for your specific needs.

Published on  Updated on