Fraying/breaking top thread on 111-155

[suzelle]

On 3/15/2022 at 3:54 PM, blue duck said:

Still trying to sort this out. (Birthday present is going to be late :{ , oh well)

Good Morning Kathi (Blue Duck) 

I hope you are making some progress with your machine. Just checking on you. I'm wondering if you have cleaned everything in that bobbin area. Try to remove all the dust, lint, stray threads. Then oil what needs oiling. Might help the parts to function better? If you can remove that bobbin case you may find some dried oil and some stray threads underneath. I'm not a mechanic, but it's always the first thing I will do, before anything else.

[suzelle]

On 3/15/2022 at 3:54 PM, blue duck said:

Still trying to sort this out. (Birthday present is going to be late :{ , oh well)

So when I said I could feel it grab, right where this 90* spot on the needle guard is where it seems to be. I had this replaced by an campbell bosworth in tx and they returned the original with the machine. The two seem quite different. The original is one piece and the edges are rounded and flowing. The replacement is, well not. The split is large enough for thread to go between. You can see quite clearly how different they are. So it makes me question if it is even a correct replacement. Ideas and or opinions? Do you think it a good idea or possiblity to change them around? Or does this even seem like it could be the culprit?

I would gladly pay for the repair, but nothing is close, which is why I sent it to Texas the first time. Shipping right now is insane though, so can't do that. 

Kathi, looking at your pics and reading again what you had written... I have a couple questions.

1- When did you send the machine to get the hook replaced. Was it years ago or recent enough that they will help you? What brand hook did they put in the macine? Is there a part number for it? Asking because I personally would want to know if the hook was one that is of a higher quality? Is it HEROSI (?) Is it another High quality brand? If it's not a high quality hook, exactly what is it? Did the Company who replaced it put that information on your Invoice for reference?

2- Are there any other parts that were replaced during the repair(s) and if so, what are the part numbers for those?

3- What bobbins do you have in it? Are you using one that is made for that hook? In other words, does it fit perfectly in the bobbin case? Is the bobbin thread stitching with no problems? If problems, what is happening to the bottom thread now?

Edited March 17, 2022 by suzelle

[Wizcrafts]

On 3/14/2022 at 4:32 PM, blue duck said:

I then spent hours trying to replicate problem to document it and found that the upper thread would go to the wrong side of the hook when going around the bobbin. (I hope I have the right terms here). You can feel it when it happens.  If you look to the right side at the top the bobbin latch, you can see where it has gone in between instead of over.

There are a couple things that can cause this. One is loosely bonded thread. Another if overly taut thread and another is retarded timing. The fixes are listed below.

1. If the top thread is loosely bonded it will tend to unravel at the slightest provocation. Further, single needle lockstitch machines are meant to use reverse (Z) twist thread. If perchance your thread has a right twist, it will loosen and unravel as you sew. Try using a different or newer spool of thread on top!
2. If the top thread is held taut all the way down as the needle bar approaches BDC, the loop will be small and tight. This can be corrected via the check spring travel limiter bracket that stops the downward motion of the spring. Set this for the best results by loosening the bracket set screw and handwheeling until the needle moves down to the top of the feed dog. Stop there and adjust the bracket so it stops the spring from going any lower.
3. You might also change the position of the small screw in the curved slot on the check spring disks. The top thread needs some slack thread to function properly. This is controlled by the aforementioned position of the check disks. Moving the disks clockwise reduces the amount of slack. Moving counterclockwise adds more slack thread. I find that if the top thread is snapping as it goes around the hook and bobbin case, adding more slack quiets it down and makes for more controllable sewing.
4. The hook to needle timing affects how the top thread loop is picked off the needle and wrapped around the bobbin case. Sometimes, retarded timing lets bad things happen as the thread goes around the case. It also causes the top thread to snap as it goes around (when it doesn't jam) Try advancing the hook slightly and see if that solves your problem.A combination of tweaking the hook timing and check spring may correct the shredding problem if everything else has been ruled out.

[blue duck]

Good Morning All!

I would like to thank you all for your advice. I have spent hours/days and tried everything you all suggested. Between each change, I would check if it corrected the problem. So at this point I can't tell if it is still catching (original problem). After all of this was completed, it appears to work when just hand wheeling it. But when I put any material to actually sew, it now won't make a stitch. It appears to me that the loop is not being made at the bottom of the stroke, but just barely under the material, too late and too high for the hook to catch. Take the material out and watch it, it makes the loop, catches it just fine. So I am sure open to further suggestions. 

1. Checked to make sure thread was correct twist. Also changed spools.

2. Changed needle sizes.

3. Bypassed thread guide on needle bar. 

4. Actually didn't mess with the bobbin tension, as that seemed okay.

5. Looked up @Uwe and re-timed according to his video. @Wizcrafts you were right the timing did appear retarded.

6. Wiz was also correct about the check spring, it was very tight. The screw was also bottomed out to the far right. The top tension always seemed tight, but got a good stitch out of it. I think this was my problem here instead of the tension discs themselves. 

@suzelle The work was done quite awhile ago. Yes they also replaced the whole tension unit. I can't find any branding on it. The bobbin thread never seemed to be a problem as far as I could tell. I had never really looked and seen the difference in the replacement unit, until this started happening. It really only caught my attention as it seemed that is where it would grab. 

Thank you all again. 

[toxo]

1 hour ago, blue duck said:

Good Morning All!

I would like to thank you all for your advice. I have spent hours/days and tried everything you all suggested. Between each change, I would check if it corrected the problem. So at this point I can't tell if it is still catching (original problem). After all of this was completed, it appears to work when just hand wheeling it. But when I put any material to actually sew, it now won't make a stitch. It appears to me that the loop is not being made at the bottom of the stroke, but just barely under the material, too late and too high for the hook to catch. Take the material out and watch it, it makes the loop, catches it just fine. So I am sure open to further suggestions. 

1. Checked to make sure thread was correct twist. Also changed spools.

2. Changed needle sizes.

3. Bypassed thread guide on needle bar. 

4. Actually didn't mess with the bobbin tension, as that seemed okay.

5. Looked up @Uwe and re-timed according to his video. @Wizcrafts you were right the timing did appear retarded.

6. Wiz was also correct about the check spring, it was very tight. The screw was also bottomed out to the far right. The top tension always seemed tight, but got a good stitch out of it. I think this was my problem here instead of the tension discs themselves. 

@suzelle The work was done quite awhile ago. Yes they also replaced the whole tension unit. I can't find any branding on it. The bobbin thread never seemed to be a problem as far as I could tell. I had never really looked and seen the difference in the replacement unit, until this started happening. It really only caught my attention as it seemed that is where it would grab. 

Thank you all again. 

You say you haven't touched the bobbin tension? That could've been the problem all along. If the bobbin tension is too tight then you'll have to tighten the top tension to make up for it. In practice the job of a balanced tension is to get the "knot" in between the two layers. Too much top tension can actually bend the needle so the hook can't get to the loop. Loosen the bobbin tension and then ease off the top tension until that knot is in the middle. If the knot can be seen on the underside then slacken off the bobbin tension some more. We're talking maybe half a turn on the bobbin tension at a time,

[Constabulary]

looks like your needle bar is missing the tread guide.

I would also try lowering the needle bar a tiny bit even when you think the timing is right. That makes the thread loop a little bit wider when the needle rises - worth trying I´d say.

Furthermore - you have installed a hook for heavier thread. There is a variant of this hook for lighter thread as well. Not sure at what thread size it is recommended but it is an option. The difference is a small raised tip on the hook gib. But different hook would be the last thing I would try. See pictures

Have you tried heavier thread in the bobbin case - meaning #92 top and bottom?

Maybe try a slightly needle like 130 metric.

 

Edited March 21, 2022 by Constabulary

[Constabulary]

2 hours ago, Constabulary said:

Maybe try a slightly needle like 130 metric.

slightly larger I wanted to write

[Uwe]

On 3/14/2022 at 4:32 PM, blue duck said:

I then spent hours trying to replicate problem to document it and found that the upper thread would go to the wrong side of the hook when going around the bobbin. (I hope I have the right terms here). You can feel it when it happens.  If you look to the right side at the top the bobbin latch, you can see where it has gone in between instead of over

This may have to do with a design issue of those hooks. If you stop the machine at precisely the wrong moment, the thread may fall down and go under the hook. Six years ago we had a topic explaining the problem and potential fixes here:

 

 

Edited March 21, 2022 by Uwe