# Bizarre tension problem



## myndzi (Mar 18, 2008)

(Tajima TME-HC912)
I've been working at my current job for a few years now, and during that time, my friend and I have been into just about everything in our machine you could get into. We've found and corrected many problems and got it running in pretty good shape. There are, however, a few problems that pop up occasionally that just baffle me. Here is one from today:

On some jobs, the balance between the bobbin thread and the upper thread will be lopsided. I've tried adjusting just about everything there is to adjust to either make this problem worse, better, or simply occur, without any success. I'll include a scan from today's run:

So much for "thirds"!

Check out the "O" especially, the way the bobbin thread sort-of "spirals" from one edge to the other, moebius style.

Does anyone know what is causing this?


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## ecreations (Jul 14, 2007)

Last time this happened to me, the problem was under the spring tension on my bobbin case. As we do more work, change bobbin thread from one to a another, I notice that it somehow accumulate some small particles either from thread or backing material and somehow got under the spring tension. First I tried spraying it with compress air to speed up the process but it would stay, so when this starts happening, I would either replace the bobbin case or remove the spring tension and clean the pathway for the bobbin thread and retension, then everything will work fine. Hope this helps.


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## myndzi (Mar 18, 2008)

I wish it was that, but the problem doesn't move with the bobbin case. (That is, I can swap the bobbin with a head that is sewing fine and the problem stays where it is)

I'll try it with a new bobbin case anyway just to see what happens...


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## dan-ann (Oct 25, 2007)

not knowing what kind of machine you have - If that happens to me I clean the bobbin case loosen the little screw so you can really get in there( just don't take it out as it is impossible to find if it falls)and then check the tension on the case. If that does not take care of it I work with the top tension. But only when i am desparate. The top tensions are preset and I find if I mess with them I only make matters worse

sally


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## sewon (Sep 4, 2007)

My first guess was dust in the bobbin case also, but if that doesn't help, also clean around all the thread guides up top. Dust and gunk can also cause problems there. Good luck.


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## myndzi (Mar 18, 2008)

I appreciate the suggestions, but I think that maybe I should elaborate some. During the time I have observed this, I have, on various occasions, tested, replaced, or rebuilt the following:

Thread path (of course), thread spool (same color), thread spool (different color), needle (to the extent we have any to play with -- 75 sharp, 80, 100, and 75 ball I think), tension wheel, felt packing, check spring quality and adjustment (near or far from the thread break sensor stop), 
bobbin case, rotary hook timing (advanced, retarded, up to 20 degrees either way in 5 degree increments), rotary hook gap (nearer or farther both), rotary hook (replaced with new one), bobbin case tension (loose, tight, and many in between, ~15-45 grams), bobbin case (replace, swap with a working one), needle depth, take-up lever timing (to what extent I could do so), and additionally we have rebuilt all the heads within the past couple years with the exception of completely replacing all the tension assemblies. Also have replaced the Y-axis drive belts (longer ago) and the X-axis drive belt (with a better belt, more recently), removed slop from the tubular frame in general along various places, experimented with the tubular frame "angle" (adjusting the rollers that support the frame vertically up or down)

To date I haven't been able to cause this problem to worsen, lessen, or move from one head to another. It confounded me for the longest time and I figured I must be doing something wrong, and then we got another machine (a Happy) which I've hardly had to touch at all and sews perfectly centered, even, satin stitches. The thing that I can't figure out is why the "column" in the back is skewed in one direction; I can't think of any reason that a tension problem would cause this (since the tension would be the same on both sides of the stitch).

Not all of these changes were done specifically with this problem in mind, but many of the more applicable ones (such as tension adjustments and playing with the bobbin/hook/upper tension) were done specifically when I had a case that I could reproduce the problem in an obvious way (like yesterday). I am going to spend a couple hours on it this morning but I don't expect much.

Thank you guys for your time!


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## XYLisa (Jan 20, 2008)

Have you figured your problem out? I wondered what material and backing you are using. The backing looks awfully thin it may just be a matter or putting heavier or maybe 2 pieces of backing (especially if what you are sewing on is thin) Looks like between the 2 they are thin and actually pulling, probably down toward the bobbin that's why you see it looking lopsided. Hope this helps.


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## deChez (Nov 10, 2007)

I've sewn thing out without backing (either forgot to put it on, or it slipped away) and never got a result like that.

What's going on there is just bizarre. I'm stalking this post to see if somebody comes up with the answer.


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## XYLisa (Jan 20, 2008)

depends on the weight of the material you have on top too though, you sew on lite cotton and thin backing it's not going to be pretty. If you think it's mechanical have you had a tech come out and tune up your machine. If you use it a lot it's a good idea to pay one to come out once in a while. We have them tune all 4 of ours up when he comes out.


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## myndzi (Mar 18, 2008)

Well I have a probable answer but haven't been able to test it. My best guess at the moment is that it is vertical bounce in the frame, due in part to it not being supported well (not as reinforced as, say, our Happy tubular frame), and possibly due to the needle plates (our tubular plates were all screwed up so there was a decision made to use the hat plates on everything). Once upon a time I was able to affect the problem by changing to the proper needle plates, but it wasn't completely convincing. It was enough that I decided to use them anyway, but there were other problems that made them unusable.


(If you think about the hoop sorta like a drum, getting pushed "towards" the raised center of the needle plate seems like it'd cause it to "bounce" upwards, while pulling it inwards wouldn't have the same effect. That's my best current guess, I just have to convince some other people that it's correct...)

Re: backing: backing and material have varied, though it's hardest when the material is very thin (less thread used in a stitch, so there's not as much breathing room to adjust it out). In this sample the fabric was a PC61 port authority t-shirt with 3oz cutaway backing.


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## Elie Tannous (11 mo ago)

myndzi said:


> (Tajima TME-HC912)
> I've been working at my current job for a few years now, and during that time, my friend and I have been into just about everything in our machine you could get into. We've found and corrected many problems and got it running in pretty good shape. There are, however, a few problems that pop up occasionally that just baffle me. Here is one from today:
> 
> On some jobs, the balance between the bobbin thread and the upper thread will be lopsided. I've tried adjusting just about everything there is to adjust to either make this problem worse, better, or simply occur, without any success. I'll include a scan from today's run:
> ...


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## Elie Tannous (11 mo ago)

Hello I own Tajima tmfxii-1206 it will make me crazy it stops continuously without breaking the thread and does not stop when the thread is broken what should I do please anyone who knows what I should do tell me I really need help in this matter


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