steihy

To continue the bobbin discussion... could have been, maybe has been...a thread of it's own. I'm concerned about the rims and total smoothness. When I test for tension by pulling thread off, I try to detect unevenness. I worry about little jerks and snags in the action that imply something worn or imperfect.
Obvious nicks and warps can be detected, polished and straightened, but any snaggy bobbin that I can't fix, is out. I don't care how nice and shiny it is, if it snags, it's out.
I know a lot of people consider vintage steel bobbins far superior to modern ones, and won't consider plastic. I will not argue with that. However, I prefer a smooth, good quality plastic one to a bad steel one. Especially in the Singers with the drop in bobbins, I usually get smoother delivery from plastic bobbins than with the steel ones that come with the machine.
A steel bobbin will retain any warp or unevenness it suffers, sometimes very small and hard to spot. Plastic will either break or bounce back.
Another factor my local retired mechanic is adamant about, is that steel bobbins, especially imperfect ones, will wear the housing more than plastic ones.
The proof of the pudding is in the stitch quality and consistency. Maybe I'm on the wrong track, and would love to hear what experienced sewers think.
I'm not suggesting the problem that started this thread is in the bobbins, I think that has been covered by experienced sewers and quilters.