Originally Posted by
KenmoreGal2
Thanks for this thread!! It helps us both.
Does the use of the machine cause the bobbin tension to slowly change? I find from time to time I have to tweak it. I usually use the machine in question for piecing so the tension setting should not change. And yet it does, from time to time. Perhaps over months. I wonder if the sheer vibrations of the machine can loosen/tighten the tension screw in the bobbin case.
If it seems I have to really turn the dial a long way on the upper tension, I take out the bobbin and do the yo yo test. Sometimes my bobbin has gotten tighter. I loosen it just a tad and I can put my upper tension back in the neighborhood where I think it should be.
(I have notes of where I get good stitches for piecing on my upper tension dial.)
On a related note, how much should one change the bobbin tension? I usually limit myself to 1/4 turn. Is that the right range?
The bobbin tension shouldn't change just from the vibration of the machine. I would be curious to see what happened if you used a touch of nail polish over top of the screw to hold it in place. Or if you just want to see what it's doing without trying to hold it, mark it with a sharpie. If the tension still changes, you can see if the screw changed position. If it didn't change position, it's likely lint and other visitors under the tension spring. If it does change, chances are good that the screw or the threads on the case are a little worn allowing it to move some.
When's the last time you took both tensions apart and cleaned them up? Starting from a known good does wonders for troubleshooting. If I start finding myself having to turn up the top tension to match the bobbin tension (assuming I know that the bobbin tension and bobbin thread haven't changed), I assume I need to clean my top tensioner. Not floss it. Disassemble and clean it.
I allow tension changes until it works right.
Typically, if I have to change more than about 1/4 turn though, I disassemble and find out why. It could be a deformed tension spring, lint, oil and debris, etc. It's rare for a properly operating tensioner (top or bottom) to change without assistance. When you start to have trouble with one or the other changing - pull on both threads. They should feel about the same. If one is way easier to pull - it's loosened up.
Originally Posted by
KenmoreGal2
Oh, another question.
I recently had an issue with skipping stitches. Do skipping stitches have anything to do with tension? If so, what is the mechanism for a tension issue to cause a stitch to skip?
Wow, thanks so much for letting us pick your brain!!
Skipping stitches can be tension - usually too tight because the thread is too tight to form the loop for the hook to jump through. That said, really loose tension could in theory cause the loop to flag and the hook to miss it but I think it's less likely. Do I vaguely remember your skipped stitches being during FMQ? If that's the case, look at your FMQ foot. I have one foot (the purple "Big Foot") that hangs up on the needle bar and causes skipped stitches. If the darning foot doesn't control the fabric and lets it move up and down with the needle stroke (flagging), the loop doesn't form properly and causes skipped stitches.