Help Seamsters! Why???

[hppyfngy]

Sewing 101. I probably need that class.

Thanks gents.

[Ramblinrev]

A problem with the sewing tensions should not affect the bobbin in that way. Assuming I am looking at the photos properly the snarls are all coming out of bobbin. Now it _is_ possible the type of material changes the way in which the bobbin is drawn down. But a properly wound bobbin should not do that at all.

Do you completely empty the bobbin before rewinding it? You should.

[WetRivrRat]

I had a similar issue with my old machine where the same bird's nest would form, but it would form between the presser foot, the feed dogs (the 'advancer' that moves the fabric) and the top of the bobbin race - almost like the feed dogs weren't causing the fabric to advance, and there was excess top tension yet an abundance of excess thread from the bobbin which would then bird's nest at the top of the race.
If I kept the material I was sewing taught then this bird's nest wouldn't happen, but the second I would let go and try to continue to sew it would happen. The feed dogs would work, but it was almost like it was out of sync.
Now, full disclosure - that machine was already a refurb, so who's to know what the previous issues with it were, but I ended up getting so pissed that I bought a new one. As in a real new one...
The race was vertically oriented, where as the new machine has a horizontally oriented one. Another thing to consider is if your machine has different 'programs'. Depending on the program that your machine is set to, it may turn the feed dogs off, which could present the same issue I had, except that my machine didn't have a setting/program to turn them off. I know it doesn't help you much as I haven't been able to provide any resolution, but I would recommend either taking it into a repair facility or ringing the manufacture (or just ring the repair shop) and trying to get on the line with their support folk.
Maybe its just something simple (... ...) like an adjustment, a quick tune-up, or program/stitch setting. Maybe its something stupid like a piece of excess material that's fallen inside and is knocking the thread at a certain point with all of the right conditions.

[hppyfngy]

Well, I just don't know what to make of this thing. I've changed back to a new #12, taken it apart and cleaned it yet again, checked my tension, spun up two fresh bobbins with great care, and I can still only go half throttle.

It's too new for the dogs to be worn and the bobbins are new. The bobbin case is perfect.

The jam up starts with a kind of a thump, like something hits something. It's muffled and not metallic and not that noticeable, but you feel it. The birds nest is all below the plate and I have to cut the thread with a seam ripper to release the fabric.

Good news is I can stumble along at half speed and that's almost as fast as I can go anyway. (Fold and sew, repeat... 6-8 inches at a time...)

Might have to take it in and have it checked out after all...

[DemostiX]

This recent sewist does not exercise the discipline to make sure everything is done right before making changes. No point in making adjustments to tension to bar tack some heavy straps, if I have not taken care that the top thread has not become dislodged from the staging point above the tension assembly. Because if it has become dislodged on this sm, it falls OUT of the tensioner, creating, of course, a bird nest beneath the plate and above the bobbin case. Duh, but I wasn't paying attention that every stage of the set-up remained intact while fiddling with one. Don't make my mistake.

Along with RR, I misunderstood, until your recent post, where the bird nest was. On your report, that nest is typical of lost tension regulation during stitch formation. Stitches are not being pulled up tight. Your description of the feel is exactly what happens when multiple loops of thread are being pulled between bobbin case and housing in a space designed for the thickness of just one thread.

Be sure the top thread is down between the tension discs, not floating halfway. Or, if your machine isn't old enough to be served alcohol, follow your manual regarding needle bar position when you thread it into the black-box slots. If problems persist, cleaning of the tensioning mechanism -- a pair of kissing lip-disks on machines old enough to drink (and old enough to be long-dead of cirhossis)--is called for. At the least on such oldsters, you can slide a fabric strip between the discs to clean out lint.

[Ramblinrev]

The jam up starts with a kind of a thump, like something hits something. It's muffled and not metallic and not that noticeable, but you feel it. The birds nest is all below the plate and I have to cut the thread with a seam ripper to release the fabric.

Ok... we now have a better idea of what is going on. First of all check you spool (upper) tension. The easiest way to do that is to thread the machine and the needle. Don't worry about the bobbin right now. Put the needle and the take up lever about half way with the presser foot up. Now pull on the tag end of the needle thread.

Lower the presser foot (don't catch the thread) and pull again. You should feel a significant difference between the two pulls. The pull with the presser foot up should be much easier than with the presser foot down. If it is not then you have a problem with the spool tension system which will do exactly what you are describing.

[Pag]

Also check the needle plate for any nicks or burrs. Really any nick or burr that the thread goes by AFTER the thread take up lever.

I would suspect you either have a tension problem or your thread is getting caught somewhere and not getting pulled up by the take up lever.

[hppyfngy]

Ok... we now have a better idea of what is going on. First of all check you spool (upper) tension. The easiest way to do that is to thread the machine and the needle. Don't worry about the bobbin right now. Put the needle and the take up lever about half way with the presser foot up. Now pull on the tag end of the needle thread.

Lower the presser foot (don't catch the thread) and pull again. You should feel a significant difference between the two pulls. The pull with the presser foot up should be much easier than with the presser foot down. If it is not then you have a problem with the spool tension system which will do exactly what you are describing.

With the presser foot up there is almost no tension. In fact there may be nothing but friction. With the foot down there is considerable tension.

I think it passed this test.

[Ramblinrev]

With the presser foot up there is almost no tension. In fact there may be nothing but friction. With the foot down there is considerable tension.

I think it passed this test.

That is the way it should be. Turn the upper tension to its maximum and try to sew. If it still happens then Pag is most propbably correct. There is a burr somewhere. Ideally your upper tension should be set around the center of the range.

[JohnSawyer]

Is the bobbin installed properly? There is a right and wrong way...

I've seen this when I'm going to fast, and the bobbin thread pulls out of the tensioner...

With Tex40 thread, I normally use a bigger needle... seems to work better on my crummy machine..