Tension problem How do you adjust the bobbin tension? the top seems tight and the bottom very loose, so getting a horrible loopy stich

If the threads on the back are loopy, you need to tighten the top tension. If you have a spare piece you may want to run some of the plastic through the machine until you get the tension correct. If the top tension is too loose, the stitching will just pull out.

try a new needle--one that is for the fabric being sewed
then try to adjust the top thread tension again, if the stitches remain loose and the tension won't adjust then the tension knob needs to be checked to see if there is something wrong with it.
also check to make sure the bobbin is inserted correctly into the bobbin case, if the bobbin is not turned the right way in the bobbin case the sewing machine will not stitch correctly.

Hi:

Ok... so try to remember that loopy stuff on top means the bobbin tension is too loose (or the top tension is too tight...)

Loopy stuff on bottom, means the top tension is too loose. (or it's not threaded right)

Now. Get some scrap of the same material. Loosen that bobbin back to where it was. RETHREAD the top, with the foot in the UP position.

Place your scrap under the foot, and sew. still have problem? clip your threads and try again only this time hold the top and bottom threads off to the side as you begin to sew. How did that do?

Adjust the top tension to the point where you start seeing the bobbin thread come up in loops to the top... then back off until the disappear.

Now... be sure you have the correct thread and needle for your fabric. A lot of problem are caused by not having the proper needle and thread.

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).

Tighten the top tension. To check the bobbin tension take the bobbin out and dangle it by the thread like you would hold a yo yo. A gentle flick of the wrist should cause the bobbin to drop down some but not just spin out to the floor, ie there should be some tension. If it hits the floor it is too loose. But if it doesn't release, fall, some it is too tight.

When you stitch a broad zig zag if the tension is correct it will look identical on the top as it does on the bottom. If it is smaller on the top then the bobbin is too tight. If it is smaller on the bottom than the top tension is too tight etc.

Usually thread too loose on the bottom is caused by the upper tension being too loose. The top and bottom tensions work together with the top thread making the underside of the stitch seem too taunt or too loose and the bobbin thread causing the top side of the stitch to be loopy or too tight. Select a large zig zag stick and sew a couple of inches. Then examine the stitch. It should look identical on both sides. Look to see which side is drawn too tight, the zig zag being smaller on that side with threads from the bottom threads pulled through. Then adjust the two tensions so that they make a uniform, identical stitch.

Also, when the bobbin tension is right you can hold the bobbin dangling by the thread and it won't spool out to the floor but will let loose a bit with a slight flick of the wrist. Too loose it will just spool out. Too tight and it won't drop at all. When you get that set right then do the above zig zag test to see where the top tension should be set.

Loops stitches on the underside is typically from the TOP tension being too loose, however it can also be the bobbin tension is too tight, or a problem with the needle. I would check them in that order.

Hold the bobbin thread and let the bobbin dangle. A slight shake of your hand should allow the bobbin to move downward (lets more thread out) but not so much that it just drops to the floor. When you put it in again and try sewing look at the top stitches. Do they look overly tight? THen the bobbin tension is too tight. The stitching should look the same top and bottom with no loops.

If both tensions seem to be alright check to see if the needle is: 1. the right size and type of the fabric 2. not bent

That should fix your problem :)

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.

there is a little screw on the bobbin holder sounds like it needs to be a little tighter

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