What causes a bobbin case to go bad?

[Sams Mom]

I've lost three bobbin cases recently due the fact that they lose their ability to increase tension (ie. you can tighten the screw all the way but there is still no tension on the thread). No trauma or anything associated. They just work and then they don't. Does anyone know what happens and if there is anything I can do to fix or prevent the problem. Or do they just wear out?

Thanks,

Donna

[carolinequilts]

I think maybe a tiny piece of thread or lint can get caught in the tension spring. Use a flashlight and see if that could be it and use a stiff brush to clean and blow with compressed air. I don't think they just wear out.

[SandraG]

Make sure the little tooth on the side spring is in the hole. Every now and then I pop out the backlash spring, clean under the side spring and wipe out the case with a little ammonia water. I put a tiny drop of oil in the case then replace the bobbin spring. It is very humid in Louisiana. I keep my bobbins in a small plastic bag that i have coated with a tiny bit of oil.

The only time I have had to replace a bobbin is if it has become bent.

Sandra

[RoseCity Quilter]

I have a bad habbit of dropping my bobbin cases and they sure do bend easy! I too have noticed lint builds up around the little "tooth". I started blowing it out with my air compresser with every bobbin change, helps a lot.

[Chocoholic]

As others have mentioned you can get lint in various places in the bobbin case. The one that always gets me is under the little 'finger' (where the thread goes through the slot it goes under the 'finger'). You need to blow that out good with your air compressor and then your bobbin case should tighten up properly again.

Another problem can be the brake spring. Sometimes you can fix this by just slightly bending out the two prongs that are on the spring. These should always stick out towards you as you look into the empty bobbin case, and sometimes they get flattened. Other times you can't get it fixed and just need to get a new spring. Cheaper than buying a whole new bobbin case.