A Guide to Using Bobbins & Hembobs

In order to discuss these sewing notions, first we need a little background on how lockstitch sewing machines work. In lockstitch machines, there are two threads — the upper thread and the lower thread. The lower thread is what's wound around the bobbin. When a stitch is formed, the needle, which has the upper thread threaded through its eye, passes through the fabric assembly. A hook on the bobbin shuttle catches the upper thread and throws it around the bobbin. The two threads are then interlocked, forming a lockstitch. The knot created by the threads is buried between the layers of your fabric assembly so it's hidden.

Hembobs vs Bobbins

All lockstitch sewing machines have a bobbin case. The bobbin case is located under the needle plate and it houses the bobbin. A bobbin is a small metal cylinder in your sewing machine that holds the thread that completes the bottom stitch. Before you start a new sewing project, you have to wind the bobbin with the thread from the cone or spool you'll be using. Then you install the bobbin in its case below the needle plate. Now you're ready to sew.

So how does a hembob differ from a bobbin? Well, in simple terms, a hembob is a pre-wound bobbin. Hembobs go by many names including belbobs and barbobs, and a lot of sewers just refer to them as pre-wound bobbins. They are sold by most of the major thread manufacturers.

At Sailrite®, we sell hembobs in sizes Tex 70 and Tex 90 in polyester UV treated thread. We offer these hembobs in two different sizes to fit whichever Sailrite sewing machine you own. The Ultrafeed uses a Class 15 or Style A bobbin, and the Fabricator and Professional machines use a Style M bobbin. All of our hembobs come in packs of 12 and have roughly 25 to 58 yards of thread on them depending on the bobbin style and thread size.

Why Use Hembobs?

Hembobs can be a great option for a variety of reasons. They save you the time and hassle of winding your own bobbins. On most home sewing machines, you have to stop sewing in order to wind the bobbin. Using pre-wound hembobs eliminates this sometimes frustrating and time-consuming task.

A lot of sewers like using pre-wound bobbins and for good reason. Hembobs are wound by high-tech, professional machines that wind the thread in a much smoother and more uniform method than a self-wound bobbin. This results in more thread on the bobbin, which means less time spent replacing bobbins and more time spent sewing. Another benefit of hembobs is that they don't have flanges like bobbins do, which is another reason hembobs hold more thread than self-wound bobbins. More thread on the hembob also results in longer continuous seams for a more professional, polished look when working on large sewing projects.

An Easy Fix for Overfilled Hembobs

As we've just discussed, hembobs are a great notion you should consider incorporating into your sewing toolbox. However, sometimes there's a small issue that occurs with pre-wound bobbins. We're going to tell you how to fix this problem so you can get back to your project.

Some pre-wound hembobs sold by manufacturers are overfilled. They have too much thread on them. What happens is this: You load the hembob into your bobbin case, bring the thread up, then you start sewing. And nothing happens. The machine won't sew. Don't worry — it's not you, it's the hembob. When hembobs are overfilled, they won't work in your sewing machine.

Luckily, we have a very simple remedy for this. Simply pull off the first foot of thread. This will prevent the excess thread from getting bound in the bobbin case. Once you have about a foot of thread pulled off, install the hembob in the bobbin case. Once installed, pull off another foot of thread. This will ensure that the thread is flowing freely and any excess glue from the manufacturer has been removed. Now you can install the bobbin case in the machine. Thread the machine as usual and you will be able to sew without issue.

How to Wind a Bobbin

If you'd rather save money by winding your own bobbins, we're going to teach you the right way to wind a bobbin. You don't want to fill the entire bobbin to the very edge of the discs. When winding a bobbin, fill the bobbin to about 80% of the bobbin's outside diameter or to 1/16 inch from the edge of the discs. If you overfill the bobbin, the thread will jam in the bobbin case, just like with pre-wound hembobs. This rule applies to both metal and plastic bobbins.

When winding a bobbin, it's important to make sure the thread is filling the bobbin evenly. If the thread is filling faster on the bottom of the bobbin than the top, you'll need to make some simple adjustments to the thread tensioning system on the sewing machine to correct this issue. You want your bobbin to be evenly filled for a successful sewing experience.

Watch the video below to see how to properly wind a bobbin.

More Bobbin & Hembob Tips:

1. If you're sewing a small project like a tote or duffle bag, use a hembob in both the bobbin case and on the spool pin for the upper thread. That way, you will run out of thread at the same time and you can keep an eye on how much thread you have left on the hembobs.

Pro Tip: If you are experiencing tension issues when using a hembob in the bobbin case and as your topstitch, reduce the tension in both the bobbin case and the machine's upper tension assembly. That should help with any visible knots or loose stitches you may experience.

2. If you're getting ready to start a large sewing project, do yourself a big favor and wind all your spare bobbins before you begin. You will thank yourself later when you're in the middle of your project and don't have to stop to wind extra bobbins.

3. Did you know that the Fabricator Sewing Machine can wind bobbins while you sew? The Industrial Thread Stand holds two cones of thread so you can sew with one and wind bobbins with the other.