Thread Break and Machine Jump

[J&O Enterprises]

Hi All,

In 2 months 1 Amaya has a demonstrated a nasty habit of breaking a thread, then displacing the next stiches (has done so 3 times). Once the thread breaks, the machine moves about 0.2" down in the Y-Axis. If you do not catch it immediately, you ruin a garmet.

There is a particular "sound/sequence" the machine makes during the thread break which may indicate the machine is going to move uncommanded. Let me try to describe the sound:
1. Normal sewing sound
2. Small hangup and 'slap' of thread results in a small ball of thread on top of the stiching (almost like it "shoots" a ball of thread through the needle
2.a - may shred thread and continue to sew at this point.
3. Sewing sound gets rougher
4. Slightly louder 'slap' and then break/shred.

Is this what happens if the thread get caught on the rotary hook?
Thanks,
Jim

[J&O Enterprises]

Has anyone else experienced a thread-break, then uncommanded movement of the machine? Some how after the thread breaks the machine moves the hoop about 0.25". This REALLY screws up things! The adjacent machine sewed the same design, same shirt, same backing, beautifully, and the problem machine had a bunch of thread breaks. Being that it happens across several colors, I'm thinking that possibly something in the rotary hook is the culprit. Any idea?
Thanks,
Jim

[signman]

When I've seen this happen...it is because the thread didn't 'cut' when it was supposed to, but the needle bar moves to the next color and/or the hoop moves to the next sewing spot-pulling the
thread (still connected) and finally ending up tight enough to snap the thread off. Before it breaks, it has prevented the hoop from moving to where it 'should' have stopped-and the 'slingshot' effect of the thread breaking will cause the hoop to jump (sometimes) but most often the thread didn't break until it had pulled so hard it shifted the MATERIAL inside the hoop...and now you are no longer aligned.
That's all I can think of...

[J&O Enterprises]

Thanks. I'll check the cutting action and ensure it is clean. The reasoning sounds good. Also noteworthy is that the shirt remained perfectly hooped. Nothing happened such that the shirt came out or shifted in the hoop. Thanks,
Jim

[J&O Enterprises]

HI All, I can offer a little more insight into this problem. While sewing this weekend, I "heard" the machine change pitch like it does before this problem occurs, and immediately hit the stop button. I stopped it before the thread could break and saw that the thread had become wrapped around the needle! So, somewhere in this problem/phenomina is that the thread actually wraps around the needle while still being threaded through the eye.

Anyone seen this before???
Thanks,

[signman]

You'll get used to your red 'baby' and soon will know just from the sound what the thread and needle is doing-we can identify when the thread hasn't broken but has frayed and made an unraveling knot travel up the thread.
Anytime we get funky thread problems (and here's a scary one-the thread is STILL sewn down, in the image...and yet is not through the eye of the needle-no break....wooweeoooweeoooo....)
we start with checking the needle tip for a burr, slide your fingernail down the needle-not up. Then check for 'centering' the needle using the commands in settings-make sure the needle isn't rubbing the needleplate. Final setting is to check the pressor foot position-with the hooped fabric in place. I constantly forget to change this and may run 3-4 different items for the same job- sweat shirt, pique shirt, jacket, etc. and with the wrong pressor foot setting, the thread can loop around the needle easily. Checking these 3 things can save a lot of thread breaks or fraying or looping problems.

[J&O Enterprises]

Hi All,

I haven't posted in a while due to some competing interests and an un-intented post-Christmas lull in buisness. However, things seem to be back on track now.

I can now offer more insight into this "thread-slap" and "machine-jump" scenario. I happend to stop my machine exactly at the perfect moment to see how this "ball-of-thread" ends up on top of the material!!!!!!!!!!!!!!!!!!!!!!!!!!!

Somewhere after the thread traces through the needle bars, and before it gets to eye of the needle, the thread is ruptured or just frayed so that one strand is cut. OR - as the thread is stretched during the needle bars action, it is semi-cut and the now loose thread shoots through the needle eye and sit on top of material as a loose ball of thread. The needle keeps sewing and stitches on top of this new ball of thread.

Seeing this, I believe the fundamental question is "why does the thread cut or break right before it gets to the needle (maybe 2-4 inches up from the needle)?"

I also changed spools of thread and it made no difference.
Thanks,
Jim W.

[Rod or Sharon]

Jim,
The answer to your fundamental question, "why does the thread cut or break right before it gets to the needle (maybe 2-4 inches up from the needle)?", is this.

Discounting the possibility that there is acually a defect in that section of the thread, the number one cause is found in the needle area.

In training some time ago, it was pointed out that at approximately 1200spm, any given piece of thread from the cone to the needle, will then pass back and forth through the needle approximately 40 times before it is actually laid down on the garment!!!! This would apply to a normal length stitch.

Think about this. The Amaya feeds thread to the take-up levers by a computer controlled procedure. The needle bar and needle will then pull this slack thread down through the garment and pick up the bobbin thread. The take-up lever will then take up the slack, pulling the thread back up through the material and through the needle until the thread is pulled tightly at the upper top of the take-up levers stroke. The motion is then repeated, rubbing the thread back and forth through the entire thread path.

If there is a burr on the needle, think of how many chances this burr has to "snag" the thread as it pushes and pulls the thread back and forth through the fabric! A burr inside the needle eye, a needle that is turned to the left or too far to the right or is bent, a rotary hook that is not timed properly, a burr or roughness on any part of the thread path from the cone to the garment OR the garment fabric it self. Dry thread, old thread, brand of thread, needle shape and size, dense designs or narrow columns as in small lettering are nasty little culprits too. Pushing thread back and forth through butter is a lot easier than trying to push it back and forth through sandpaper..

Hope this gives you some insight on the fundamental question of "why". This does not cover all the possibilities, but should give you some things to think about.

Rod Springer
Melco Tech & Trainer

[J&O Enterprises]

Rod - OUTSTANDING explanation and information on the process of the thread and sewing action! Three stars friend!!!!!!

This is one good reason to not really question why you change needles when stuff starts to go bad - just change them and see if something changes for the positive.

Also, on one of my machines I did increase the needle gap slightly. It looked like the needle was almost touching the case. I used a 0.002 feeler guage to set the gap and I saw an improvement right there.

I think now that the gap is fixed, I may try a "small" hook adjustment to see if that completely alleviates the problem.

Thanks,!!!!!!!

[Rod or Sharon]

Jim,
Whoa---hold it...hold it ....not too fast here...;-})

To understand the hook timing process you need to also understand how and why it is done like it is.

The gap you mention is called the "needle guard gap." Whenever the left to right position of the hook to the hook point is set, the needle guard gap should be set at the same time.

Under the table top there are some numbers hand written on the lower right corner of the machine base. Numbers like 199.9--200.0 200.2 etc, will be the hook timing position. Other numbers and letters like, C-1 through C-16 will be an indication of the "closest" needle. Numbers and letters like F-1 through F-16 will be an indication of the "fartherest" needle.

If you were to try to place the needle case on a centerline, what you would find is that some of the needles would be on this line and some of them would be either on one side of the line or the other. The differences are regulated in the thousands of an inch, but there are differences.It is just a matter of machining tolerances in play here.

The hook timing is always acomplished with the machine color changed to the closest needle position. What this means is that when you set the needle guard gap up as closely as possible, the gap between the face of the hook and the backside of the needle will be extremely close as well. All the other needles, unless they measure exactly on this centerline, will be farther away from the face of the hook, meaning that the space between the backside of the needle, inside the scarf indention, has gotten larger. Don't forget that with the machine setting at it's hook timing target number, the face of the needle is also setting inside the scarf on the backside of the needle. The operator must know that the needle is properly aligned, with the groove on the front of the needle facing straight forward, that it is seated all the way up in the needle bar and that the needle is not bent.

So, when doing a hook timing procedure, it is important that the procedure be done in a very methodical, careful and very accurate manner, using the closest needle as the starting point.

Thanks for the 3 stars---it is sometimes a lot eaiser to trouble shoot when you have some understanding of the process involved.


Rod Springer
Melco Tech & Trainer.

[Debbie Rinehart]

Rod and Sharon,
My machine has been stopping at the beginning of a new line of words, on the very first letter of a word. After the thread is cut on the previous line, the needle starts on the new word and will travel about 6-7 stitches but it seems to me that the bobbin thread is not getting pulled up by the top thread. Why does this happen and if it's happening a lot, is there something I can do to stop it? THANKS for the help. Debbie in Indiana

[Rod or Sharon]

Debbie,
The font style and size is sometimes important. Is there tie-ins and tie-offs in this lettering and if so what style tie-in and tie-off are you using. Changing the style of tie-in is sometimes all that is needed.It sounds as if the inching stitch count is not picking up the bobbin or if you are using auto-actifeed, it may be causing a very loose condition in the thread because of excess thread being fed by the computer on start up. This causes a loose thread condition around the thread break sensor and it will think that the thread is broken and stop the machine.Try going to Standard and manually setting the material thickness to see if the problem is happening there also. You could also try reducing the inching stitch count to see if that would help in this case.

Rod Springer
Melco Tech & Trainer

[Debbie Rinehart]

Rod,
It probably is my inching stitch count since I'm not using acti-feed. I have noticed that after many of the color changes, the first 5-6 stitches are VERY loopie, but the rest of the design is perfect (well, almost LOL). So, I guess I need to go in and look for the inching stitch count setting. I'll probably check the tie in as well. I use 3 different digitizing programs ( Generation, Viking and Design Shop), so it could be one or the other is a slacker. THANKS-THANKS-THANKS!!! You guys really are the BEST!! Debbie in Indiana

[J&O Enterprises]

Team - Fortune Favors the Bold! There is a point at which the sewing will be bad enough as to warrant stopping the machine. Reaching that point I decided to adjust the hook timing/gap. Using the instruction book and the nifty photos of the "front-view" of the bobbin case, hook, & needle, I could easily see that the hook had become retarded somewhat (hook was about 1/8" behind, to the right, of the needle).

Using the maintenance menu and hook-timing step to rotate the hook such that I could use a flat-tipped screw driver to loosen the 3 screws, I found that two of them were VERY loose. Seeing this I re-positioned the hook and set the gap as best I could and did some practice sew-outs.

No surprise, the sewing quality was GREATLY improved and I could finish my garments.

Now that I see Rod's comments above, I will take to setting it as accurately as I can and according to the numbers. In the maintenance menu, using the head-timing tab, those numbers are clearly identified every time you hit the tab. I will get it exact though!

Thank you again for the input!!! Also, I have not been to training, but have been doing embroidery for 3 years and are mechanically inclined (and even read instructions from time to time).

Thanks,
Jim

[J&O Enterprises]

Rod,

Last night I popped off the table top and saw the C11 and F2 needle designations, and the 200 marker. On the maintenance window, head timing tab, I just double clicked on the position and input 200. The machine jumped to 200.1, so I figured this was close enough. I reset the needle to #11, and adjusted the hook position and gap.

I sewed both of my AMAYAs on the same design with a small lettering font. The newly set machine was still had a few more thread breaks than the other one, but in general was improved greatly as noted before. It is interesting that this one machine seems to break a few more threads than the other on on the same design.
Thanks,
Jim