I am sewing a strip of velcro on to a piece of nylon. No matter if the velcro is on the top or the bottom it is loopy and nesting on the underside. I have the Singer curvy and have the tension set on auto. I have also turned the tension dial in either direction with the same result. Thank you in advance for any thoughts.

it is called bird nesting and the upper thread tension is not tight enough
Proper needle thread tension is when you feel resistance as you pull the thread through the needle eye

Not knowing your machine make/model, this is a guess. Be sure to Always Raise the presser foot when threading the top thread. This makes sure the thread is fully seated in the tension disk.

Adjust your top tension if it's too tight. To decrease your top tension if it is too tight, turn your knob so the numbers are decreasing. Try ½ to 1 number lower, then test the stitches on a piece of scrap fabric. Continue until it looks even on both sides and you can no longer see the bottom thread on the top.

How to Adjust the Tension on a Sewing Machine: 13 Steps

www.wikihow.com/Adjust-the-Tension-on-a-Sewing-Machine https://www.google.co.uk/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=Sewing+Machines+Setting+tensions

Rethread the top of the machine with the presser foot up; sew with the presser foot down. If the fabric is too thick/too many plies, the presser foot is forced upwards, allowing the top tension to open. This causes thread snarls on the underside. See also: http://www.picturetrail.com/sfx/album/view/22521551

try adjusting the top thread tension one number or letter higher
and sew on a scrap piece of fabric till the stitches look normal.

it is called bird nesting and indicates that the needle thread is not tight enough

It is in your top threading, something is not right in the path. Always remember, it is the opposite of what you think. So, underside will mean that the top thread is the problem

You didn't give the brand, but if it's any of the older, non computerized machines, your problem is most likley in the tensions.
Loopies (tangles or nests of thread) on the bottom means upper tension too loose (or bobbin too tight).
Let's do the bobbin first...once it is set...99.9% of loopies on the underside are a problem with upper tension.
This is for bobbins that load on the front/side of the machine.. Take out the bobbin case...check the area (hook/race area) that the bobbin goes into for lint, tiny thread pieces, etc.). Now, most of this type of bobbin loads into the case with the thread going counter clockwise (when you are looking at the open side of the case), insert the bobbin in the case, and pull it through the hole/slott in the side of the bobbin case. To test for proper tension:
Lay the bobbin case in the palm of one hand, pull on the thread coming off the bobbin case. The bobbin will gently lift off your hand & if you wiggle the thread, the bobbin case should slowly drop about an inch at a time. If it's too tight, loosen the Larger (closest to where the thread comes out) screw on the side of the bobbin case about 1/16 of a turn...tiny bit...retest. Once that is done try a test stitchout. Remember to hold onto the bobbin & top thread for first few stitches.

If you still get loopies on the bottom...tighten the upper tension...it should be set between 4-5 for regular sewing.
Make sure the needle is in properly.

For a drop in bobbin...adjusting that tension is harder. You take the face plate (needle plate, the plate covering the sewing area of the machine) off and remove the bobbin case...First...look at the case in the machine...there is a little lip sticking out, usually at the bottom right corner of the open area (closest to you)...this is where you need to have the little lip when you replace the bobbin case.
Remove the case...check under it and inside the machine for lint/dust/threads & using a small paint brush (I use a childs tooth brush sometimes), clean the lint out. Now check the bobbin case for lint, especially where the thread fits..look at the inside of the case, you will see a little flat metal thing with a slott in it...make sure no lint in that slott. I use a pin to remove lint from there. Reinsert the bobbin case, rethread it all, (bobbin goes counterclockwise). Put the faceplate back on & test the stitches...still loopies with the upper set to between 4-5? Then you will remove the faceplate, remove the bobbin case & loosen the screw on the outside about 1/16 of a turn (these are usually covered in a colored coating) and retest.
I know that most home machine makers say not to adjust the bobbin..but that was back when you had one size thread...now we have many, many sizes and types of thread, so adjusting the bobbin may be needed sometimes.
Rule of thumb is:
loopies on underside...tighten upper tension
loopies on top...loosen upper tension.
But, like I said...with all the new threads..sometimes you have to adjust that bobbin.

Hi Lou! This sounds like a tension problem--the tension on the top thread is too loose. Try using different color threads on the top and bobbin, then carefully rethread everything. Stitch a couple of inches and check the underside. If the top stitches look fine and the bottom ones are loose and loopy, and with the pressure foot down, tighten the tension. Move the knob or dial (whichever you have) just a little bit. Sew a couple of inches more, and recheck. Continue to sew and recheck, gradually tightening the tension, until you see little if any bobbin thread on the top or top thread on the underside of the fabric.

Let me know if this helps, ok?


Robbie

First check to see if your bobbin is in right, if it is check your top tension...