The rule is 30% of the bobbin showing on the bottom. Once adjusted properly you should not have to make to many adjustments. Remember that the bobbin and the top thread pull on each other when the take up arm snaps up, so if your bobbin pulls all the way to the top you have a tension problem not a fabric problem. Your most likely going to experience missed stitches with that much tension mis-match. As the needle starts up the thread forms a loop that the rotary hook catches, forming the stitch. I say this because you have to think of thread tension in terms of both upper and lower thread. You can tighten the bobbin tension and pull the top thread down, but that may result in too much 'pull' between the top and bottom, resulting in poor loop formation, and so poor quality stitching. If you don't have a tension gauge, pull the bobbin out and try the old drop test. Hold the bobbin thread between your fingers and let the bobbin (in the case) dangle, jerk the thread just a bit and the bobbin & case should drop just an inch or two, if not adjust until it does. Once you happy with the bobbin tension sew out a test and adjust the top tension. One note, different threads can require different tensions, pick the brand/type you like and stick to it. If you have a combo machine and youÂre using cotton for sewing and switch to rayon or polyester for embroidery your going to have problems, same with the bobbin. Best to get a good quality bobbin thread and top thread and stay with it. Good Luck.

I've had this problem as well...didn't even realize that the bobbin thread not rising up was the cause. After a bit of focused experimenting a few minutes ago I realized there is no inherent tension in the bobbin thread area (despite the design of the machine!). So with the bobbin cover removed and the presser foot UP if I set the bobbin as normal and held the end of the thread off to the side AND applied a bit of tension to it I could get the needle to pick it up perfectly. Tested it and sewing was normal! Maybe the needle needing to be changed contributes to jams but I have run that scenario of changing it and everything else in complete frustration over this problem until I saw what was really happening...which tends to occur out of the blue...knowing I can manually get the machine to pick up the thread allows me to continue using a needle that is still serviceable. Tip: I read that some people remove the presser foot to get access to the threads but I use a small plastic tool that is shaped like a crochet hook to grab the thread back after getting it- safer and time saving for when this happens. Hope it helps others to know.

Have you checked the needle size? Is it the right one for your heavy duty thread? Is the bobbin thread spooling off the bobbin case in the right direction? Test this by taking the bobbin out, turn it around and put it back in. If there is no change then that's probably not the problem. Have you tried adjusting the top tension? I suspect the top thread may be too loose. If you're not comfortable messing with the tension (it takes some time to get it right) take it to someone who is familiar with your machine and can do it for you. Oh yes! Is the needle inserted properly? The groove faces out. This groove helps to guide your thread into the eye so would not work if in backwards.

Hi, My machine was skipping stitches and it could be the same problem. The bobbin case sometimes gets thread caught in it. I ran a thin straight pin between the pieces that create the tension and it fixed it. You could also try using thread in it like dental floss, back and forth. Thread gets jammed there just like it gets jammed in the upper machine. Also, check the bobbin case area and under the feed dog plate to make sure there's no thread caught in it and make sure the 'hook' that pulls the thread around the bobbin case is moving freely. Did you do anything about the same time that it stopped working, like thread the top or bobbin, or change the needle? If the needle is in wrong or it's not threaded properly, it won't pick up the bobbin thread. Hope that helps. Linda