<!-- from fixya rte -->How do I thread top thread - Necchi 6018 Mechanical Sewing Machine

Top thread nesting on bottom side is likely either top thread has escaped tension plates or tension too low. Try increasing tension.

You can test top thread tension by setting tension at 2, then with foot up (zero tension) make long steady pull of top thread. Then move foot down and make another pull of top thread. There should be na notable difference. If no change in tension when foot down, rethread top.

Top thread tension with foot down should be similar to bottom thread (bobbin) tension.

Be sure it is top thread. Use a different color top vs bottom color to know for sure. If you find it is bottom thread, likely cause is thread escaped bobbin case tension spring, reload bobbin.

Check that top thread tensioner is engaging.

After threading top thread, with presser foot up, rotate tension selector to 4. Then move presser foot down (this engages top thread tensioner). Make a slow steady pull of the top thread. Compare tension to when foot was up (no tension) to foot down (selected tension). If you move presser foot up and down while slowly pulling the top thread, you should feel the change from no tension to selected tension.

If you find there is no tension on the top thread, the top thread will loop and nest on bottom side of fabric. Rethread top thread per machine instruction. If still no top thread tension, either the tensioning mechanism has failed or it has not threaded properly.

Once you have verified the top thread tensioner is working, you need to check bobbin thread tension. Make a slow steady pull on the bottom thread. You should feel tension similar to the top thread with tension selector set to 4 and foot down. If the bottom thread tension feels loose, similar to top thread presser foot up, then likely the bottom thread has escaped the bobbin case tensioner. Reload bobbin and recheck bobbin tension.

Pull a bit on those loose stitches and verify it is actually the bobbin thread that is loose. Usually, the looping is the top thread. As a general rule, if the thread problem appears on the bottom of the fabric, it's a top thread issue. If the problem appears on the top of the fabric, it is a bobbin thread issue.

If it is a top thread problem, try increasing the top tension. If it continues to create loops under the fabric, you need to rethread the top thread as follows:

Remove the top thread from the machine.
ALWAYS RAISE the presser foot and rethread from the beginning.
Then tweak the top thread tension until the top and bobbin threads meet in the middle of the fabric.

Increasing the top tension will bring the bobbin thread higher into the fabric. Decreasing the top tension will allow the bobbin thread to pull the top thread down into the fabric. You want a happy medium between the two. That is correct tension.

So, it sounds like the bobbin thread is coming to the top of the fabric and the top thread simply lays on top of the fabric. Just a hint: If the thread problem appears on top of the fabric, it is usually a bobbin thread problem. If the thread problem appears under the fabric, it is a top thread problem.

Is the top thread tight, ie pulling the bobbin thread up? Try loosening the top tension.

If that doesn't resolve the problem, then you probably need to tighten the bobbin tension.

Understanding Thread Tension on Your Sewing Machine

Generally, bobbin tension is set at the factory and is usually a "last attempt" to alter. Sounds like you are probably experiencing bird nesting or thread nesting which is a top thread issue.

Be sure to install a brand new needle.
Remove the top thread from the machine.
ALWAYS RAISE the presser foot and rethread the top thread.
Set the top tension to the mid-point and retest your machine.

Tension is correct when top and bobbin threads meet in the middle of the fabric. It is a tug of war between the two threads. When there is equal pull, the top thread pulls the bobbin thread up and the bobbin thread pulls the top thread down. Increasing the top tension pulls the bobbin thread further up, decreasing top tension will allow the bobbin thread to pull the top thread down.

Understanding Thread Tension Threads

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Remove the top thread from your machine (NOTE: ALWAYS clip the thread next to the spool, lift the presser foot, and gently pull the top thread down from top to bottom!!! This helps reduce the chances of breaking something by pulling the thread upwards!)

ALWAYS RAISE the presser foot and rethread the top thread from beginning. Verify the thread path is correct and start out with the thread tension set at the midway point (and then tweak the top thread tension through testing).

FWIW, if the thread problem appears under the fabric, it is generally a top thread issue. If the thread problem appears on the top of the fabric, it is generally a bobbin thread issue.

What causes Bird Nests Superior Threads

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

CURED Sewing Thread Nests on the bottom


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Clip the top thread next to the spool. Raise the presser foot and pull the clipped thread DOWN through the needle eye. (Always remove the top thread in this manner. NEVER pull the top thread up!!!)

Now, ALWAYS RAISE the presser foot and rethread the top thread. Verify the thread path is correct.

Set the top tension to the midway point (then tweak the tension by testing).

If the bobbin thread is still pulling out, the top thread tension needs to be tightened. The tension is correct when the top thread and bobbin thread meet in the middle of the fabric.

Understanding Thread Tension Threads

How to Achieve Ideal Sewing Machine Thread Tension Threads

Sewing Lesson 10 How to Fix Tension on Your Sewing Machine

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Is it really the bobbin thread that is bunching? Generally, thread messes under the fabric are the fault of the top thread, and thread messes on top of the fabric are a bobbin problem.

Top thread bunching under the fabric is called "thread nesting" or "bird nesting" but I prefer to call it thread "barfs." Most often, it occurs because the top thread has not been seated completely in the tension disk.

Install a brand new needle.
Remove the top thread from the machine.
RAISE the presser foot and rethread the top thread.
(Verify the thread path is correct.)
Set the top tension disk at the midway point.

Retest your machine. Tweak the top tension if required.

The bobbin thread is being pulled too hard by the top thread. The idea is to get an even pull similar to a tug of war. When it is even the thread will form a knot in the middle of the fabric.
To fix this so the top thread isn't pulling too hard lower the tension of the top thread. This should fix it.

THE BOTTOM AND TOP THREADS ARE IN A TUG OF WAR. WHEN THE TOP IS TOO LOOSE THE BOBBIN WILL BE PULLING HARDER THAN THE TOP THREAD SO A GREAT DEAL MORE THREAD WILL END UP ON THE BOTTOM. TO CORRECT THIS YOU INCREASE THE TOP THREAD TENSION. IF THE TOP THREAD IS PULLING HARDER THAN THE BOTTOM THEN A GREAT DEAL MORE BOBBIN THREAD WILL END UP ON THE TOP. TO CORRECT THIS YOU WOULD LOWER THE TENSION ON TOP.