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Sewing Machines Part 2 - Bobbins

Sewing Machines Part 2 - Bobbins 

Bobbins are just as important as the top threading mechanisms of your sewing machine. Bobbin tension matters. For that matter, so does the size of your bobbin thread. You may want to change the color to match the bottom layer of what you will be sewing on, or have it match the top thread. That’s your choice. Many people keep their filled bobbins with the spool of thread it was wound from. I just keep all my bobbins together in the case from the sewing machine. I have a good number of bobbins for each machine. That way I can have a variety of colors and sizes wound all the time. Most are wound with 50wt or 60wt neutrals, one has a 100wt poly for paper piecing, and I try to have an empty for specific colors to be wound for a specific project. If I’m piecing a large quilt, I can have a couple of bobbins wound with the same color. That way I don’t have to stop so often to refill the bobbin.


Let’s start with the bobbin itself. Each machine has a specific size bobbin it uses. Make sure you have the correct one in the bobbin case. If you don’t use the correct size, no matter what else you do, the tension will be off, it may loop on the bottom, or just not sew. Check your owner’s manual or online for the correct size for your machine. The most common sizes are Class L, Class M, Class A(Class 15). Class L and A/15 are about the size of an American nickel across. They are different heights. Class M is about the size of an American quarter. Class 66 are like the Class 15 but are slightly rounded on the outside. I keep Class A(Class 15) in-stock, and try to keep Class L in-stock. Bernina and Viking machines use their own brand bobbins. The other brands may use a standard size. Just check first before getting new bobbins. Click here for The Thread Exchange's chart for checking your machine’s bobbin size.

You need to check the edges of your bobbins and bobbin casings for sharp spots or burrs. These will cause your threads to shred or break. You should retire these bobbins. You may be able to use a nail file to get the burr off the bobbin case. Or try getting the bobbin case fixed by your machine service people or just buy a new one.

You need to make sure that your bobbins are wound tight and even. Watch as your bobbin winds your thread - the thread should be taut and winding up and down the whole length of the bobbin core. You can also purchase pre-wound bobbins. These are convenient and save you time. These also are wound a little tighter and have more thread on them. You can purchase them in sets of one color or a rainbow of colors. I have some 50wt cotton ones from Superior threads in the shop. I haven’t tried the cardboard ones in any of my machines, but the internet says they are fine to use and dispose of when empty.

Let’s review how the bobbin works. The top thread drops down by the needle dropping down. The bobbin mechanism/shuttle hook catches the top thread and pulls it around the bobbin, thus catching the bobbin thread. The needle pulls the top thread back up and the bobbin thread is pulled up through the throat plate. Even tension on the top and bottom keep the threads pulling evenly between the fabric layers. If the tension is off, the thread will pull to the top or bottom, or loop on the bottom. 


Bobbin problems are solved, usually, the same way top thread sewing problems are solved. Bobbin problems can be:

1) Thread not up and sewing

2) Tension off – pulling up or down too much, or looping underneath

3) Thread stuck/machine jammed or not sewing

4) Bobbin thread breaking a lot


Try these things first:

1) Rethread your machine – top and bottom. Make sure you have snapped the bobbin through the tension piece. You can hear/feel it click into place. Sometimes the bobbin thread curls and won’t come up to sew. Just rethread it and have a long tail.

2) Check your needle size and condition. It may be too small a needle for your thread size. This will pull on the needle and either break the thread, bend the needle, or break the needle. The needle may be past it’s use – burrs from lots of use, worn needle hole. CHANGE THE NEEDLE! Needles wear out faster than you think.

3) Check your thread size and the condition of your thread. Thread from grandma or mom may need to be thrown away. Cotton does dry rot over time. Too large will put too much tension on the bobbin case, too small just slides through.

4) Clean the machine – pop the throat plate, pull out the bobbin case, clean out everything. Do not clean by blowing canned air into the machine. Use a vacuum to pull the lint out or a wand. Clean the bobbin case too. Here's a good video on cleaning your case.

5) Check the upper tension. You may need to increase or decrease it.

6)  If 5) doesn’t work, check the bobbin case tension and adjust it if needed. Both horizontal and vertical cases have one screw that is a little larger than the rest. That can be turned. Clockwise to tighten, counterclockwise to loosen the tension. Reset your top tension to its standard setting first. If the thread is looping below or pulling so the bobbin thread is straight and the top thread is little bumps on the bottom, loosen by a quarter turn at a time. If the bobbin is being pulled up to the top, tighten by a quarter turn at a time. Do a test sew after each turn.


7) For vertical bobbins, you can check the tension by hanging the bobbin and casing by the thread. If it hangs and doesn’t slide when just hanging and drops about 1”-2” at the most when you shake the bobbin; the bobbin tension is good.

8) Make sure the needle isn’t hitting the bobbin case or shuttle hook. This will hurt the bobbin case and needle. It could put burrs on both. The timing could be off or the bobbin case/bobbin isn’t in all the way. The vertical bobbin cases should click into place and the case should not wobble. Flat bobbins should be totally horizontal and not wobble.

9) If the machine is stuck, not moving – try getting the bobbin out carefully. There could be thread caught in the bobbin mechanism. Try getting the thread out. Sometimes I need to cut the thread where it is attached to the fabric. I can then pull out all the stuck threads. THEN, GIVE THE MACHINE A GOOD CLEANING! (For Singer Featherweights, if the machine/bobbin is stuck; you will need to have it serviced to get the thread out. This usually happens when you turn the wheel backwards for any vertical bobbin machine).

10) If it is looping below, check that your top thread hasn’t popped out of the upper tension arm that pulls the tread back up.

11) If none of the above works – take your machine for a spa day


A couple of other things –
            Thread throw-up and bobbin barf - this is the mess you get at the beginning of your seams from the loose ends of thread from the top and bobbin get tangled with the sewing. Start with long thread tails and hold them when you start sewing. This will keep everything looking better, not tangled, and pressing nicer.

            The quality of your fabric, thread, and batting effects how your machine works. Poor quality of any of these means lots of lint in your machine. So clean your machine often if you are using fabric inherited from Aunt Tilda or bought at a yard sale. Michael’s is now advertising they have the largest selection of fabric in the area. They may, but the quality of what they will carry and their customer service won’t match your local quilt store.

      The cotton thread we carry lints less than most. Because it is cotton, natural fibers are shorter and will lint some. Polyester threads will lint less. For fabric, the base(substraight), used for fabric determines how nice a hand the fabric has. The nicer the hand (feels good to touch, smooth, drapes well or hold its shape), the less lint. You want batting to be soft and clean too. You don’t want stems, leaves, etc. in the batting.

      Because what we have is the store is mostly cotton products, there will be some lint when you sew. Just be aware of this and clean your machine accordingly. You saw what my machines looked like, and they get cleaned a lot.


Saturday is National Quilting Day and March is National Sewing/Crafting Month. Bring us a quilt, completed quilt top (lap or larger), or other completed sewing project to share and get 20% off your fabric purchase this week.

Wearin’ O the Green may get you a goody on Wednesday.

Happy sewing

Phyllis and the QA staff

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