Stitch Not Locking Although The Upper Tension Is Good - Consew 225 / Singer 111W155 / Juki 563

[Ken B]

Thank you for any ideas, I am not sure what to try next.

I was having a "rats nest" on the bottom side, but I've gone through all of the timing points in the Navy manual, and now I have the topside looking great, and the bottom side with the bobbin thread just running in a straight line and the spool thread pulled up against it.

I have increased the tension to a ridiculous amount and it didn't make any difference. The tension assembly is not disengaging, I adjusted it temporarily so that it doesn't open the tension discs even when the presser feet are raised. The tensions discs are not bad either, there is definitely no lack of tension on the spool thread.

I read in the Navy manual that this problem happens when the eccentric is out of timing, and when the bobbin case opener isn't adjusted correctly and doing its job. I've adjusted both.

Any ideas are appreciated! Thank you.

[CowboyBob]

I think you need to make sure your needle thread is pulled down in between the tensions discs,if not it'll just what you say because you aren't getting enough tension on the thread.Also have you taken the nut off the tension post & take the discs apart to see if there is grooves or dirt in there?

[Ken B]

Hi Bob, thanks for the reply. The thread is between the tension disks. The tension is working because I can turn the tension to half way and it's nearly impossible to get the thread through, but as I back the tension off it starts to slide easier. I've tried with multiple threads and needle combinations as well with the same results.

[Northmount]

Too much bottom tension?

Tom

[Ken B]

Thanks for the thought Tom! But, unfortunately the bottom tension is good. I even swapped the hook assembly to see if it was somehow binding on the old basket. I've watched from up above and from underneath the machine and everything seems to be functioning normally, except that my stitch isn't locking. It's driving me mad!

From what I can tell the top and bottom tension are good, and my problem is from some component being out of time, or adjustment, but I can't figure out which.

Tomorrow I will take a detailed video, perhaps something obvious will pop out to one of you experienced people that is eluding me; I'm new to these industrial machines.

Edited February 2, 2014 by Ken B

[Wizcrafts]

First, make sure that the needle is ascending as the hook point approaches. It should intersect the needle, inside the cut-out scarf, about 1/8 inch above the eye. If that isn't happening, e.g, the hook intersects right at the level of the eye, the loop cannot form in time to be picked up. Ditto, if the hook arrives after the eye has passed it completely, or too low on the upstroke.

How about your loop? Is is persisting as the hook reaches the scarf of the needle, above the eye? Or, is the loop dissolving before it can get picked off? A dissolving loop can be caused by too much swing of the check spring, or if you fail to feed the top thread around the spring at all.

If the material is very sticky, the top thread might stick to the needle and the loop may not form at all. This sometimes happens when we use double-sided leather tape to hold layers together.

[Ken B]

The loop forms, picks up the bottom thread fine, but the stitch does not lock like it should (I apologize if that isn't the correct terminology), it just has the bottom thread pressed up against the material with the top thread looped around it. If I pull the bottom thread it will pull right out and unlock the stitch.

[Northmount]

So there is too much tension on the bobbin. Reduce the bobbin tension a quarter turn at a time. You stated you have lots of tension on the top, trying to pull the knot up into the leather. The leather, hole size (needle size), thread size top and bottom, and the bottom tension have to work together to place the knot in the middle. If you have the right needle and thread sizes, the only thing left is the bottom tension.

If I use too large a thread in my bobbin, it won't pull out easy enough. The slot in the bobbin is too small.

The bottom tension should be about half the top tension.

Tom

[CowboyBob]

Yes,loosening the bobbin tension alittle will help,you also might give the takeup spring more pressure .

[Ken B]

Thanks guys, I will try the bottom tension again ... yep, that did fix it! I didn't think it could possibly be the bobbin tension because it was only 1/4th the tension of the top thread, but I loosened it to where it basically has zero tension on it and now it stitches fine. I'd even swapped the hook assembly / bobbin to one from Juki that supports up to #208 thread, and I'm using Tex 60 with a size 19 needle.

Hopefully this thread can help out other newbies into looking at the bobbin tension. Thanks so much for all of the feedback, I really appreciate it! You guys are awesome.