I cannot stress to you enough the importance of using the correct bobbin for your sewing machine. This is an easily missed detail for many reasons. One thing I've noticed with sewing machine manuals over the years, specifically with modern sewing machines, is that while the user manual will mention you need bobbins, they don't bother to tell you what type of bobbin your machine uses. And this is infuriating because your machine cannot operate properly with the wrong bobbin type.
What I also see is that a customer might inherit or acquire a machine, and it may or may not have the correct bobbins with it. Or, if you own more than one machine and they use different bobbins, how do you keep track of what bobbin goes with what machine?
My biggest beef with the companies that manufacture machines, and thus, manufacture sewing machine bobbins, is that there are ZERO indicators on the bobbins to tell you what brand or type they are. A few of them have features that make it easy (i.e. Viking bobbins are green - they come in other colors, but mostly you see green ones). Metal Bernina bobbins have a knurled center post. But aside from those instances, it's difficult to determine one bobbin type from another.
Here is my favorite trick for determining the bobbin your machine uses. It uses the Sewing Parts Online website, which is a retailer for sewing machine parts. As a bonus, SPO is a good, reputable resource for ordering replacement bobbins when you need them. They typically have additional savings with a coupon code, so check the upper bar of the website for a coupon code, or Google search "Sewing Parts Online coupon code", and usually something will pop up.
1. Visit the Sewing Parts Online Website (www.sewingpartsonline.com)
2. In the upper left-hand corner, hover over the "Machine Parts" header, and you'll see a list of major brands. Select the brand of your machine. If you do not see your brand listed here, please leave a comment below with your band/model of machine and I'll be happy to help.
3. After selecting the brand of your machine, you'll be taken to a screen that lists all models associated with the brand. In the search box on the screen, type in the model number.
Here you'll see I'm searching for a Singer 4423. It'll start to narrow down the list of links as you type in the model number.
4. Click on your model, and it will take you to a page showing all the parts available for your machine.
What we are most interested in is the type of bobbins. Now, you might see two different versions, one metal, and one plastic. Yes, this matters. I will cover that in more detail down below, but you'll notice that if there are both metal and plastic bobbins available, you can see that they are Class 15 bobbins in the case of this model of machine.
If you click on the bobbins, a new page will open that will give you a better idea of what the bobbin should look like. If you have multiple bobbin types and you aren't sure what's what, this is a good way to start separating them. See below for my visual reference chart. Here you'll also see options for purchasing bobbins if you need to stock up.
And if you scroll to the bottom of the page, you'll see a complete list of machines that use the same bobbins. This is a tiny sampling, as the example I used is a Class 15 bobbin, and it is probably the most widely used bobbin type across brands and models.
In another example, I searched for a Brother PE770 model of machine, and while the bobbin looks similar (clear, flat on top and bottom), it is actually very different, just not detectable to the eye. This shows why it's very important to verify what bobbin your machine uses. In this case, the Brother PE770 uses a specific Brother bobbin with the part number X52800150.
Here are a few more very helpful resources when identifying bobbins. Here is a visual chart I made that you can download and print (click for printable version):
Sewing Parts Online also has this handy reference sheet that is printable (click for printable version):
I recently discovered this website that is helpful if you are wanting to use prewound bobbins. This website sells prewound bobbins, but please know that they are NOT ALWAYS UNIVERSAL.