Random Loops In Stitching, Please Help

[NewYorkerInSydney]

Hi folks,

I have been trying to sew several layers of 10oz canvas. have a Juki 1508 so its made to handle this. However, I notice that every few inches or so, there are random loops appearing. Sometimes they're maybe a foot apart, other times theyre a few inches apart, but they're quite random. I am using 138 thread with 130/21 needle and Im also trying it with 140/24 needle. Using a 135x17 system.

I have threaded and rethreaded countless times.

I have tightened and reduced both upper and bobbin tensions several times

I have cleaned any dust that might appear anywhere

The needle is new and inserted correctly

I changed the needle a couple of times.

And I have checked and rechecked to make sure the machine is correctly threaded at the top

I have checked many times that the bobbin is in the right way.

I have also used 92 thread with a smaller needle and same problem

Can someone please tell me what I might be missing here and why I keep getting these random loops? Its making me crazy and my top stitching looks awful with these loops. They appear at the top.

I appreciate your help mostly kindly.

Thank you,

Nyis

[Constabulary]

How is your thread coming off the spool? The thread guide should be centered right above the thread spool and should be as high as possible so the thread is coming off w/o hanging. Have you tried leaving out one or two threading holes in the 3-hole guide? I most of the time leave out holes. Going through all the holes is for getting a possible twist out of the thread but thats not always necessary. These guides have nothing to do with thread tension in general but in some cases they can cause some tension with some sort of thread. Thats at least my experience. Just give it a try.

This is how I´m using the threading holes and I have zero issues.

Edited July 16, 2015 by Constabulary

[Art]

Thread ages. This is especially noticeable when the machine sets unused for a week or so; all of a sudden a perfectly running (last time) machine starts with tension problems. Usually if I have thread that is going to sit for awhile, I will spray it with a silicone lube, although it is more economical in 5 gallon wine jugs from Clearco. Alternately, I just run off or pull off a layer of thread. Changes to tension should never have to be more than just a little. If you need to make serious changes to your tension all the time, check the condition of the thread and the thread path for dry, UV affected thread, or something in the thread path like burrs etc.

Going through all the holes in the thread path does seriously affect the tension just like adding tension; more so with dryer thread, so much so that you may not be able to have enough bobbin tension to overcome it. Skip holes (not the one in the needle) and you decrease top tension.

Art

[DrmCa]

More questions than answers:

Sounds like thread tension sometimes drops and you see the loops. They are on the underside, correct?

Are the stitches the same length in the areas with the loops?

Is the pressure plate or spring hanging up sometimes as the foot and needle go down? I'd looked around the tension mechanism to see if there are any burrs or lack of lube that may prevent correct tension.

[gottaknow]

If you've tightened the top tension with no results, and the machine is threaded correctly, the next thing with random looping is the latch opener. The latch opener pulls the small tab on the bobbin basket towards the operator, allowing the needle thread thread to pass and set the stitch. The random nature of your loops is more likely to be the latch opener than the tension. Thread getting caught at any point to the needle will pull up the bobbin thread, not loop the needle thread on the bottom. Old thread can do this as well, but I'm ruling that out because you've tried different thread. If you search this forum for "latch opener" you'll find more info with pictures. I'm sitting in an airport, so I don't have the pics on my laptop.

After that, your hook timing could be suspect, but my guess is the latch opener. Have fun!

Regards, Eric

[brmax]

I have the same model and had the very same issue, I believe mine is taken care of now by more top tension or tighter though before it seemed correct. I ran 6 on the stitch length and had a consistent 8 stiches then a loop that a pencil lead would fit on the topside all else in the stitch looking perfect to me, sometimes they would not be as pronounced but there around 8-10th.

I re checked the adjustments it seemed dead on everything and this was a gov warehoused machine never used "none" anyway with no results including trying to understand and adjust the thread pull up tension spring setting. All this time running 92 coats ultra poly and solarfix 2000 though not as much issue with the latter, using new and changing 18-19 needles. I had known from checks a minimum clearance between basket tab and feed dog cover plate, though the spec range as I recall from notes .039+-.004 and mine is .035 with this I did not order a different or thinner thrust washer as I did not no the size needed from what I had in there, bad part was I had the hook out previously but not for this issue unknown at that time (could kick myself).

I don't mean to reopen this problem or to barge in here but I cannot say how much this I know sounds exactly like the issue I had and hope done with. The puzzling thing was to me why every 8-10 perfect stitches, If I understood better what the thread is actually doing through all this cycle it would help.

I don't know but do know the guys that posted already, totally do.

Good day there

Edited July 20, 2015 by brmax