Question about Janome 4623 Mechanical Sewing Machine

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Thread bunching under material

The top is sewing correctly while the underneath is bunching severly. I removed the bobbin and rewound another bobbin and it worked fine for awhile, but the same problem reaccured please advise

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Re: thread bunching under material

Ensure that all is clean and free of lint and jams, this is the most likely for tension troubleshooting .......

This solution is for tension problems...if you cannot form any sort of stitch, the issue is quite different, so please let me know if you need a different problem solved.....

It is quite long, but just work through each section in order.
The "knotting up" can reveal a lot. If you have loose threads on one side or the other, the tension on the opposite side will be the culprit.

Ensure sharp new needle,
Thread guides and Bobbin are Clean & Clear of lint
Set Top Tesion to 4 ....then....
Balance Bobbin to suit.

If the looping threads are on the underside as you sew, it is the top tension. Top tension ought to be between 4 & 6 (this variation to allow for the different weights of fabric in your

If you are using a needle that has seen quite a deal of work, or you suspect it may be blunt, change it for a new one !

Make sure that when you thread the machine the presser foot is up so the thread goes between the discs and not to one side, top tension between 4 and 6, and that you have threaded through all the guides, including the last one, usually on the needle arm, just above the needle clamp.

It may be there is lint trapped between the discs, this will keep them slightly apart and reduce the actual tension, sometimes dramatically.

If tensions appear correct, and the thread is definitely in the channel between the discs, but still too loose and looping, try raising presser foot and remove your thread.

Now, with a 2" (50mm) wide strip piece of fabric 8 - 10" (20 - 25cm) moistened with methylated or denatured spirit, gently insert the fabric strip and clean between the discs with
a see saw / to and fro action.

In the worst cases, gentle use of a needle to pick & remove the jam may be necessary, but be very gentle and make sure the tension is set at Zero and the presser foot is raised, (to
disengage tension plates).... do not gouge or score the plates, they need a polished surface to work correctly.

Far less common, but if the loose threads are on the top, it is bobbin tension that is loose, it too may have lint in the spring and be giving a "false" tension.

I would not recommend fiddling with bobbin tension without good reason, it may end up with missing small screws and spring pieces, however, you can take the needle plate off to clean
the hook race area (where bobbin case sits)

...this is just good housekeeping, my wife does this every time she replaces the bobbin....

just take it out and clean the bobbin case and the fixed metal hook race with a small brush to remove lint. If there is a significant amount of lint, use a vacuum and small brush to get the worst.

Then wipe all this area with a cloth or cotton bud (Q tip) moistened (not soaked) with methylated spirit, especially if there appears to be fine dirty deposits....oil and lint combine to conspire against you.

If it seems likely that you ......really .....actually .....need adjust the bobbin case, first check there is no lint trapped in the metal spring where the thread is tensioned.

Drop-in Bobbin case will look similar to this image with the tension screw in the middle of the metalwork....

4c76dc1.jpg ...the other screw at one end is holding it all together, so is not a tragedy to undo the whole lot and clean it, but very gingerly and lay the bits out in sequence and orientation, or you risk tearing your hair out !

When you are certain there's no trapped lint in top tension or bobbin, set the top tension to 4 and the bobbin tension to a point where you just begin to feel resistance.

Try using good quality thread of contrasting colours so you can more easily spot the changes.

Set your zigzag to one width less than maximum (eg. 5 of 6 ...or... 4 of 5 etc) and sew a sample for a few inches and check the result.... adjust the bobbin tension screw very little at
a time, perhaps 1/16 of a turn.

You may find you are playing with this balance for some little while and if you are putting the needleplate on and off each time begin to think it cannot be correct to do is,
and eventually, you do get a "feel" for the correct tension and then it happens quite a user you won't be doing it very often unless there is lint built up (or are there small hands at work around the house !?!?!)

If you live near the ocean as we do, salt air can play havoc with metalwork inside and out, so to help minimise this, keep a few small packets of dessicant (silica gel) in your machine case ? then make some sort of cover !

Same applies in any damp or humid environment, keep your machine dry and dust free.

Budget for a proper full service every couple of years (more often if heavily used) and if you don't use your machine for a few years, be aware that old oil will dry out and combining with
dust and form a "clag" like glue (another reason for some sort of cover, even a teatowel !)

If it is worth spending the time, energy and money on making something that you would like to give lasting enjoyment......use quality thread, may seem to cost a little more at the
time, but the results, ease of use and added longevity will be worth the extra, and as a bonus, your tension troubles may be fewer and further between, because there is a more consistant diameter with good thread, and less compensating to be done by your tension plates and less thread breaks !

If you want any more help with this, just post back here, or, drop a line through the "Contact Us" page at

Posted on May 10, 2008

Re: thread bunching under material

Make sure the machine is threaded correctly from the cotton reel through to the needle, I had the same problem a while back.

Posted on May 24, 2008

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Look at your seam. If you have a bunch of balled up thread underneath the seam, part of the problem is operator error. Always always grasp the thread end while beginning the seam. I suspect that the thread gut bunched up under the material and caught up in the bobbin/shuttle area.

Remove the fabric, unplug the machine... get into the bobbin area, remove the bobbin, and if necessary clean threads caught up in the bobbin race/shuttle. reassemble and replace the bobbin... turn on the machine. Try again.

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Embroidering in blue thread, and the white bobbin thread was coming through on the material. Adjusted the tension to -8, sprayed the bobbin casing and area lightly with WD40, changed the bobbin, changed...

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When i sew the bobbin thread bunches up. what to do?

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If this does not help check the tension on the top(the number should be about mid way).
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What's your problem?i have loops on the underneath of my material, or its all bunched up birds nest

try changing the needle
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Oct 31, 2011 | Singer 3116 Simple

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Hi iam not sure how explain my problem with my sewing machine.when i try to sew the strings does not comes stright. it gets messed up the top comes ok but the bottom of the layer comes out all strings...

If I'm understanding the problem right it sounds like you have no tension on the bobbin. Take it out and see if the thread has any resistance when you pull it out. If you hold it up by thel thread and let it dangle and it just drops to the floor the tension isn't right. Check and make sure it is threaded correctly and tighten the tension. Test it again and when you dangle it, it should drop a bit with resistance when you hold it by the thread.

Also check that the top tension isn't too tight, but in this case it is more likely that the bobbin is too loose. And check to see if the dogfeed (the teeth that comes through the plate opening under the needle) is up and moving the material through the presser foot. If the material isn't moving at all it will sort of stitch "in one place" which will give you a bunch of threads all knotted up underneath. If those underneath threads are loopy that is a sign the bobbin thread is too loose (tension too loose)

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My bobbin thread is bunching up underneath. I have taken the bobbin out and the bobbin assembly out but it still is doing it.


In a sewing maching, for the thread not to bunch up, there are two thread tension tighteners. One each for the bottom and the top threads. The top thread tensioner is a nut that tightens or loosens the thread tension. The thread passes under this nut. While for the bottom thread it is two screws on the casing for the bobbin. These two screws hold a small strip of metal to the casing and the thread passes under this strip.

To be able to get proper tension on both the threads you have to strike a balance on both the top and the bottom threads. If the difference is not much then you can do with varying only one of them, usually the top one for ease of functioning.

Since you say that the thread is bunching uo on the bobbin side, ie, the bottom, means that the top thread is too tight and must be loosened. You cant do it in the first go. It may take you a few attempts to get it correct, so do not loose heart if it is taking time.

All the best.

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