How do you change the tension on a bobbin for a singer 5050 We don't have an instructional manual?

Threading and tension are two different things.

You can search for a manual:
Make Model manual
or
Make Model threading
(most machines thread similarly so even if you don't find your specific model, the instructions would be helpful)

https://www.manualslib.com/products/Singer-L47-4062252.html


When threading, be sure to ALWAYS RAISE the presser foot so the thread will seat completely in the tension disk.

For tension, generally start with the tension set at the midway point. Tension is correct when the top and bobbin threads meet in the middle of the fabric. If the bobbin thread is showing on the fabric top, loosen the top tension. If the top thread is showing on the underside of the fabric, tighten the top tension. Do not adjust the bobbin tension until it has been determined that the top tension does not make the adjustments needed. (Bobbin tension is sensitive--a little change makes a big affect so you will need to know how to reverse any changes you make.)

Understanding Thread Tension Threads

I would recommend that you consult the user's manual. They are generally well-written if you take it step by step. You can get it as a free download from Singer at http://www.singerco.com/support/instruction-manuals/search.

try adjusting the top thread tension to one number higher at a time until the stitches start looking right

also check with singer customer service for a instruction manual

Top tension about 4 or 5, use a good mercerised thread only, make sure you do not have the bobbin tesnion too tight, slacken the screw anti clockwise on the bobbin case if it is

Try adjusting the tension. It sounds like the bobbin thread is too loose or the bobbin is not in correctly. Try taking the bobbin out and turning it around and putting it back. When you hold the bobbin in the fingers of your left hand and you pull the thread out with your right hand the bobbin should be turning clockwise. If the nesting persists, try ajusting the tension one way and then the other to see which seems to help. Hope this helps!

The balance stitch control on this model is below the stitch patterns; to the far right.

If you need a manual you can download a free one at the Singer Company website.

"Birdnesting" occurs when there is no tension on the needle thread to pull the bobbin thread. This is easily corrected by rethreading the machine, following the threading path carefully and making sure the thread is fully engaged in the tension mechanism.

You may have threaded the machine with the presser foot down. This closes the tension control and the thread cannot properly enter during the threading process.

Re-thread with the presser foot up.

Test the stitching.

"Birdnesting" occurs when there is no tension on the needle thread to pull the bobbin thread. This is easily corrected by rethreading the machine, following the threading path carefully and making sure the thread is fully engaged in the tension mechanism.

Take out your bobbin case... there should be a small screw fixture on the side of the case...turn screw anti clockwise until you get the correct tension ... To test the bobbin thread tension...Remove the bobbin case keeping bobbin attached and hold it by suspending it by the thread...**** it once or twice, if the tension is correct the thread will unwind by about an inch or two. If it does not unwind at all...tension is too tight. If the tension is too loose it will drop too much. Goog Luck