Quilting machine bobbins come in three main types: Class 15, Class 66, and Class L bobbins, each designed for specific machine models and thread capacities.
The key differences between quilting machine bobbins lie in their size, shape, and whether they use a removable case or drop directly into the machine.
What Are Quilting Machine Bobbins
Think of bobbins as the unsung heroes of your quilting machine. They hold the bottom thread that locks with your top thread to create every stitch.
Without the right bobbin, your beautiful quilt blocks turn into a tangled mess. You need the correct type for your machine to work properly.
How Bobbins Work in Quilting
Your quilting machine uses two threads to make each stitch. The top thread comes from your spool. The bottom thread comes from the bobbin.
These threads interlock below your fabric. This creates the strong, lasting stitches that hold your quilt together through years of use and washing.
The Three Main Types of Quilting Machine Bobbins
I found through research that most quilting machines use one of three bobbin systems. Each has its own size and loading method.
Class 15 Bobbins
Class 15 bobbins are the most common type in modern quilting machines. They measure about 20.5mm wide and 11.5mm tall.
These small bobbins drop directly into your machine. No separate case needed. You just pop them in and start quilting.
Many Brother, Janome, and Singer quilting machines use Class 15 bobbins. They’re perfect for most quilting projects.
Advantages of Class 15 Bobbins
- Easy to load and remove
- Widely available in stores
- Work well with various thread types
- Less expensive than other types
Disadvantages of Class 15 Bobbins
- Hold less thread than larger bobbins
- Need frequent refilling during big projects
- Can rattle in some older machines
Class 66 Bobbins
Class 66 bobbins are larger than Class 15. They measure about 20.5mm wide but are 13mm tall.
These bobbins usually need a removable metal case. You wind the bobbin, put it in the case, then load the whole unit into your machine.
Older Singer machines and some vintage quilting machines prefer Class 66 bobbins. They hold more thread than Class 15 types.
When You’ll Find Class 66 Bobbins
Vintage Singer Featherweight machines love Class 66 bobbins. So do many straight-stitch quilting machines from the 1950s and 1960s.
Some modern machines still use them. Check your manual if you’re not sure what type you need.
Class L Bobbins
Class L bobbins are the giants of the bobbin world. They’re wider and taller than both Class 15 and Class 66 types.
These bobbins typically measure about 27mm wide. They hold much more thread, making them great for big quilting projects.
High-end quilting machines and some industrial models use Class L bobbins. They’re less common but very useful.
Benefits of Class L Bobbins
The main benefit is thread capacity. You can quilt longer without stopping to refill your bobbin.
This makes Class L bobbins perfect for longarm quilting machines and large projects like king-size quilts.
Material Differences in Quilting Bobbins
Bobbins come in different materials. Each affects how your machine runs and how long the bobbin lasts.
Metal Bobbins
Metal bobbins are the traditional choice. They’re usually made from aluminum or steel.
Metal bobbins last longer and handle tension better. They work well with heavy threads and dense quilting patterns.
I found that many quilters prefer metal bobbins for their durability. They don’t crack or wear out as quickly as plastic ones.
Best Uses for Metal Bobbins
- Heavy quilting threads
- Dense quilting patterns
- High-speed quilting
- Professional quilting work
Plastic Bobbins
Plastic bobbins are lighter and quieter than metal ones. They’re often clear or colored, making it easy to see your thread level.
These bobbins work great for regular quilting cotton and lighter threads. They’re also less expensive than metal bobbins.
Some newer machines work better with plastic bobbins. Check your manual to see what your machine prefers.
When Plastic Bobbins Work Best
Plastic bobbins shine with regular quilting cotton and polyester threads. They’re perfect for everyday quilting projects.
Many quilters like seeing their thread level through clear plastic. No more surprise empty bobbins in the middle of a seam!
How to Identify Your Bobbin Type
Not sure what bobbin type your quilting machine uses? Here’s how to figure it out quickly.
Check Your Manual First
Your machine manual tells you exactly what bobbin type to use. Look for a section on threading or bobbin installation.
Lost your manual? Most manufacturers have them online. Search for your machine model plus “manual” or “bobbin type.”
Measure Your Current Bobbin
Grab a ruler and measure your bobbin. Width and height will tell you the class.
| Bobbin Class | Width | Height | Case Needed |
|---|---|---|---|
| Class 15 | 20.5mm | 11.5mm | No |
| Class 66 | 20.5mm | 13mm | Usually |
| Class L | 27mm | 15.5mm | Sometimes |
Look at the Loading Method
How does your bobbin go into the machine? Drop-in bobbins are usually Class 15. Bobbins that need a case are often Class 66.
This isn’t always true, but it’s a good starting point for identification.
Common Bobbin Problems and Solutions
Even with the right bobbin type, you might face some issues. Here are the most common problems and how to fix them.
Thread Tension Issues
Wrong bobbin types can mess up your thread tension. Your stitches might look loose or puckered.
Make sure you’re using the exact bobbin type your machine wants. Even small differences in size can cause tension problems.
Signs of Bobbin-Related Tension Problems
- Loose stitches on the bottom
- Thread bunching under fabric
- Uneven stitch appearance
- Thread breaking frequently
Bobbin Won’t Fit Properly
If your bobbin rattles around or won’t stay in place, you probably have the wrong size.
Double-check your measurements and manual. Sometimes bobbins look similar but have small size differences.
Thread Keeps Breaking
Thread breaks can happen when your bobbin has rough edges or isn’t wound properly.
Try a different bobbin first. If that doesn’t work, check how you’re winding your bobbin thread.
Tips for Buying the Right Bobbins
Ready to buy new bobbins for your quilting machine? Here’s what you need to know.
Stick with Your Machine’s Brand
When possible, buy bobbins made by your machine manufacturer. They’re designed to work perfectly with your specific model.
Generic bobbins can work, but they might not fit as precisely. This can lead to tension and stitching problems.
Buy in Bulk for Big Projects
If you’re working on a large quilt, consider buying extra bobbins. You can pre-wind several with your bobbin thread.
This saves time during quilting. No more stopping to rewind bobbins when you’re in the middle of a difficult section.
How Many Bobbins Do You Need
Most quilters find 10-20 bobbins work well. This gives you enough for different thread colors and big projects.
Store them in a small container so they don’t get lost or damaged.
Caring for Your Quilting Machine Bobbins
Good bobbin care extends their life and keeps your quilting smooth.
Keep Them Clean
Lint and thread bits can build up on bobbins. Clean them regularly with a small brush or compressed air.
Dirty bobbins can cause thread to catch or break. A quick cleaning prevents most bobbin-related problems.
Store Them Safely
Don’t just throw bobbins in a drawer. They can get scratched or dented, causing thread problems later.
Use a bobbin storage box or case. This keeps them organized and protects them from damage.
Conclusion
Understanding quilting machine bobbins doesn’t have to be complicated. The key is knowing your machine’s specific requirements and using the right type every time. Whether you need Class 15, Class 66, or Class L bobbins, using the correct size and material makes all the difference in your quilting success. Take time to identify your bobbin type, buy quality bobbins, and maintain them properly. Your quilting machine will reward you with smooth, even stitches that make your quilts look professional and last for generations.
Can I use any bobbin that fits in my quilting machine?
No, even if a bobbin seems to fit, slight size differences can cause tension problems and poor stitching. Always use the exact bobbin class specified in your machine manual for best results.
Why does my bobbin thread keep jamming underneath my quilt?
This usually happens when you’re using the wrong bobbin type or your bobbin isn’t inserted correctly. Check that you’re using the right bobbin class and that it’s properly seated in your machine.
How do I know when my bobbin is running low on thread?
Many modern quilting machines beep or show a warning light when bobbin thread is low. You can also check visually if you have a clear plastic bobbin or drop-in bobbin system.
Should I remove my bobbin when I’m done quilting for the day?
It’s not necessary to remove your bobbin daily, but if you won’t be quilting for several weeks, removing it prevents thread from getting stiff or creating tension in your machine’s springs.
Can I wind different thread weights on the same bobbin?
Yes, but clean off any remaining thread first. Different thread weights can affect tension, so it’s better to start with a fresh, empty bobbin when switching thread types or weights.
