What QuiltedSunshine said. If you have a metal bobbin case (probably not drop in) you can use either the metal bobbin that came with your machine or a prewound plastic bobbin. If your bobbin case is not metal (probably a drop in), use the plastic one that came with your machine. Using a plastic bobbin in a metal bobbin case won't damage it, but using a metal bobbin in a bobbin case designed for plastic can ruin the case.

Probably a dumb question, but how can you tell if your case is metal or plastic? All the cases on my machines are silver colored. I use size 15 prewound (I am lazy) plastic in all my machines, but metal in my Featherweights.

If you have a machine newer than the 90s with a drop in bobbin, chances are the bobbin case is black plastic. If your other machines are all like the FW and have a removable bobbin case, then they're all metal.

Cari

You learn something everyday...I just bought bobbins some plastic and metal to use in my Anniversary Singer Featherweight Repro 160...Now I know not to use the Metal...Thanks ladies...

I use metal bobbins in my Brother machines. Plastic is so light weight, and my hands don't work like they used to, that I drop the plastic bobbins about 50% of the time. That is rarely a problem with the metal bobbins. Maybe it's because they feel cooler in my fingers. My machines aren't super expensive, but are computerizedI've had them several years now and they seem to be working fine.

My electronic Elna's from the 1980's came with metal bobbins, now i can only replace them with plastic bobbins from the dealer. (so it uses both!)

I have only one machine that used plastic bobbins. The replacement bobbins did not work, I was limited to the 5 that came with the machine. It really needs to go to the shop. Since it has a small throat and I have 4 or 5 more I don't use it.

I think saying that you can't use metal bobbins in an electronic sewing machine is a vast over-generalization. Personally, I'd find a new SMG. I've had 2 Bernina's in the last 25 years, both used metal bobbins. I agree with using the bobbins recommended for your machine.

I agree and think the reason for this is that the metal in plastic may warp the case. I also wonder if there isn't some friction built up with bobbins/cases being different materials that might interfere with the machine computer.

Metal bobbins supposedly wear grooves in a plastic bobbin case over time. Personally, I've never seen it but I can see how it could happen. I use a metal bobbin in my Juki when it has the right color thread on it as I only have three plastic 15 class bobbins that came with it. I generally don't use this machine enough to worry about it.

Cari