How do I adjust the bottom thread tension?

Check your stitch sample. The loose stitches under the fabric--are they actually top thread???? Usually,stitch problems under the fabric is a result of a top thread problem. In this case, it could be bird nesting.

Remove the top thread from the machine.
Install a brand new needle.
ALWAYS RAISE the presser foot.
Rethread from the beginning.

Sewing Machine Thread Bunching Up Here Why

Birds nest under the fabric big loops of thread top side looks good...

You bobbin tension CAN be adjusted. First, thread your machine with different colors in the top and bobbin, set your top tension at its default, and run a line of straight, and then a line of zigzag stitches, and compare the results at the top and bottom. You will be adjusting your bobbin to your top tension. If the top tension looks like a straight line instead of stitching and the zigzag looks like "chicken tracks" instead of a zigzag, but the bottom looks like a zigzag, your bobbin tension is too loose.

Remove the bobbin case, and locate the straight-slot screw. There are generally two; one is a Phillips and one is straight--you want the straight one. Leave the other alone.

The rule is "lefty-loosy, righty-tighty." If your stitching displays the above symptoms, it needs to be tightened, so turn 1/4 turn to the right--no more--then test again. You will need patience, but don't turn more than that. It is easy to do, but if you don't do it systematically, you can make things worse, and very slight adjustments can alter the stitching significantly.

The bottom stitch is affected by the TOP thread tension :) First go back and make sure your bobbin tension is correct since you adjusted it. It should drop slightly when held suspended by danging it by the thread. If it reels out to the floor it is too loose. If it doesn't drop at all it is too tight.

Now that you have that adjusted look at your top tension. If it is loopy on the bottom side of the stitch the TOP tension is too loose. Increase the top tension.

Now take some scrap material and set machine to a wide zig zag, medium length stitch and sew a bit. Compare the top and the bottom sides of the stitch. They should look identical. Remember the TOP side effects the bottom and the BOTTOM tension effects the top side. Adjust accordingly until they look identical with no loose threads or loops and no puckering (puckering means it's too tight).

Meaning you have adjusted the tension for the top thread as well as the bobbin?

Use two distinct colors of thread - one for the top and one for the bottom.

Thread the machine with the presser foot up.

The two threads should meet in the middle of the stitch with neither obvious on the opposite side of the seam.

Set the top thread tension to 4 and adjust the bobbin as needed.

Hi! The bobbin tension rarely needs to be adjusted. First, make sure you're using the appropriate size needle and thread for your fabric (I'd probably use either a 'denim' needle or a universal size 14) and also that the upper thread and bobbin are threaded absolutely correctly. These can throw off the tension! Also, take the time to clean out the bobbin area. That can throw your stitch off also.

If the stitch on the bottom is loose, so that you see the top threads, then the top tension is too loose. If the top stitch is too loose and you see the bobbin threads on top, then the top tension is too tight.

It helps to thread the machine with different color thread on top and in the bobbin, and then stitch an inch or so on the same type of fabric as you're using in your quilt. Check the stitch. If you need to adjust the top tension, make sure the pressure foot is down! Adjust a little, stitch a few inches, and check again. Repeat until you don't see any (or very little) bobbin thread on the top or top thread on the bottom.

If you go through all these steps, and the bobbin thread is still loose (and you've tightened up the top tension), then there is a tiny little screw on the side of the bobbin case that you can use to adjust the bobbin tension. Turn the screw just a little bit (less than a quarter turn), stitch, check, etc. Once the bobbin tension is set, you shouldn't ever have to change it.

Let me know if this helps, ok?

Happy sewing!

There are tow places where the thread tension is adjusted.

One is bobbin. This is not routinely adjusted. Just once and it is good for long time. This is done by turning the only screw on bobbin by about 1/4 turn or so at a time. Try several settings until you find he best.

the other place is the conventionally on body of the machine.

Tension of bottom stitch or top stitch are very confusing words. meaning difft things to difft pple.
All i can say is this. If u see bottom stitch run straight through loops of top thread. then either top tension is too loose or bottom too tight. and vise versa.

With top tension set to middle position adjust the bobbin to get correct stitch. Then later on all u need is to adjust only the top setting according to stitch and cloth

Sounds like you may need to have the tensions adjusted. If the bobbin thread is showing on top, the bobbin tension may be too loose. If the top thread shows underneath, the top tension is probably too loose. Since you are having both problems, perhaps a technician should take a look at it.

pucker is caused by too loose or, to tight adjustment of: the thread tensioners both the bobbin tensioner and, the needle tensioner need to be adjusted: to adjust the needle tensioner turn the side knob clockwise is tighter counterclockwise loosens; the bobbin tensioner is a tiny screw on the bobbin holder adjust both tensioners until your stich loops' both top and, bottom are tight but, the machine does not break the thread

Welcome to FixYa!

Loose bottom stitches come from the top, not the bottom. Seems weird, but that's the way sewing machines work.

The dial tension should be set at the mid range and make absolutely sure that you have the machine threaded correctly. Both things will cause a sloppy bottom stitch.

Thanks!

If you find my solution helpful, I'd appreciate a FixYa rating....

If the top stitch is loose, then you need to tighten the bobbin tension: if the bottom stitch is loose, tighten the top tension. Hope this helps. It could also be the size needle and thread you are using for a particular fabric. Different fabrics require different notions.