On the Singer 401A - tension adjustment on the bobbin?

If you sew, where do you see loose thread? On the top of the fabric, or on the bottom?

If the loops are on the bottom, then the top thread is not tensioning properly -- you either didn't get it into the tension assembly properly (raise the presser foot when threading -- always!) or the thread is too heavy for the needle you're using and doesn't sit down in the thread groove of the needle properly. http://www.gwsms.com/didyouknow.htm

Try a larger needle size and an embroidery or topstitching needle.

(If you've never been into needle comparisons before, take a look at the

grooves in a size comparison here: http://www.picturetrail.com/sfx/album/view/1720679... )

If this is a heavy bobbin thread that's looping on top of the fabric, either you've got grungies under the tension spring on the bobbin case, or you've managed to jiggle that delightful little tension screw loose. Because those little bobbin screws want to hop out and run away, never to be seen again, I always put the bobbin case and a screwdriver in a plastic bag, close the bag, and then manipulate the screwdriver through the plastic. Standard screw directions -- righty-tighty, lefty-looseny -- so with heavier thread in the bobbin, you'd have to loosen the screw slightly. I make no more than a 1/8th turn adjustment on a bobbin case screw before testing it.

http://www.taunton.com/threads/pages/t00221.asp

If you just want heavy thread for topstitching, consider using regular thread in the bobbin and the topstitching thread on top. If needing to run heavier thread in the bobbin is common for you, consider buying a second bobbin case... one for regular sewing, one for messin' around with. If you have to mess around with your regular bobbin case, put a mark on it

with a extra fine sharpie marker, so you can line up the screw slot with the mark when you're ready to go back to regular thread.

If you're trying to run something like upholstery nylon #69, don't. It's too heavy for home sewing machines and it'll tear up the tension in no time at all. I wouldn't do this to a nice machine like a 401A -- I'd go get an old $10 beater from the thrift store or send the job out to the local upholstery shop because they've got the right machines to do it. Mine charges me a princely penny an inch, $2 minimum, for seaming if I don't care what color it gets sewn with and I bring it in ready to sew.

You're welcome to email me if you want to discuss your project further... I may be able to suggest ways to strengthen the seam without going to a heavier thread, if that is your issue. Or to do fake topstitching with couched threads, if that is the problem.

Singer 401 Sewing Machine

how do I replace the tension part on a 401a