JUKI 563 thread snagging on bobbin case

[matcanada]

Hello,

 

I've been following this forum for a while and it's fantastic. I have a JUKI LU-563 which is working quite well except for the fact that sometimes the upper thread catches on the bobbin case in the little nook. Anyone have any idea how to solve this problem? Thanks so much.

Edited July 3, 2019 by matcanada

[davemac2]

Are you sure the hook timing is correct?  The tension on the thread seems fairly tight going around the bobbin like the take up lever is going up too soon, upper thread tension too tight, or maybe the take up spring is not adjusted properly?  The take up spring on the upper thread tension assembly should be at its stop and applying NO thread tension once the needle has reached the fabric on its downstroke.  Also check for any burrs on the bobbin case thread slot there which may be catching the upper thread.

[Pintodeluxe]

Hmm, I've never seen one snare thread there.  Surprised it isn't a more common problem.  Dave has some good suggestions to try.  You're not getting thread caught up on the thread stand somewhere?  If so that might artificially increase upper tension and cause something like this.  

[Gregg From Keystone Sewing]

I see two important things to look at here;

There is a Simamco Singer bobbin case opening lever, this is very likely for a small or regular bobbin machine, like a Singer 111W155 or Juki LU-562.  I can't read the number well enough, but I'm willing to guess this part didn't come off of say a Singer 211 with large bobbin that may work, but not likely.  See correct Juki part number for this, very common part anyone can find on the internet for under $15 or so.

ALSO, onto the bobbin case issue.  This is becoming more common as the quality of some of the bobbins are suspect.  Poor quality with tolerances all over the place.  The OD of the bobbin as well as the inside hole can be all over the place, and I should know because I sell them too and see them come in and create issues like this.  

What happens is when the machine comes to a stop, the bobbin wants to keep spinning, and the thread pops out of the side of the bobbin.  Then you go to sew, and its tangled up in the hook are and latch.  Also, dropping in an anti backlash spring with a good quality bobbin may help here too.  This is a VERY common hook and appears on many various makes and model machines, so finding genuine Juki or better quality parts will go a long way.  This is not the 1st time I've had issues with cheap bobbins messing up the whole show.

[matcanada]

Thanks for the suggestions. The machine appears to be timed correctly and I tried  is timed correctly, so I don't think that's the problem. I should add that the thread snagging issue occurs intermittently which makes it all the more challenging for me to solve it. The part number for the bobbin case opener on the machine is SIMANCOUSA 248404. 

[mikesc]

The gap where I have circled in red..looks too small ..try loosening the screw at the other end of the lever, and increasing that gap to about 1.5mm..I also end to agree with Gregg..there are a lot of "approximately made" bobbins, and other parts around..

[Gregg From Keystone Sewing]

As I suspected, the bobbin case opener is for a small, or regular bobbin, or  G bobbin size.  This image below appears in the Singer 111W151 parts book.  I would get the correct opener in there, especially if you are having sewing problems.

Edited July 6, 2019 by Gregg From Keystone Sewing

[Gregg From Keystone Sewing]

On 7/4/2019 at 7:04 PM, mikesc said:

The gap where I have circled in red..looks too small ..try loosening the screw at the other end of the lever, and increasing that gap to about 1.5mm..I also end to agree with Gregg..there are a lot of "approximately made" bobbins, and other parts around..

 

 

[SARK9]

On the subject of aftermarket parts with wild variations in tolerances, the underside of the needleplate, where the groove which prevents the bobbin case from rotating is located, also deserves a look. I've had to increase the width slightly and ease/reshape sharp edges to allow the thread to pass smoothly without random binding or erratic tension. Also, if your hook timing is slightly retarded, you may get a momentary high tension on the needle thread as it slides across the top going around the bobbin case. This might tend to allow the thread to pop into that groove over the bobbin tension spring and wreck things. Slightly too much hook advance is less risky, within reason, and worth a try if you hear "snapping" noises as the stitches form.  As far as the cheap and variable aftermarket bobbins leaving too much gap, I submit that the "sideless" prewound bobbins leave one hell of a gap as they are unwound and used up without issue in many commercial applications. I personally only use them with certain common colors in *G* style bobbins on a Singer 111W152 which is dedicated as a binding machine, so who knows. The sideless bobbins are very uniformly wound and hold a bit more thread. As far as the anti-backlash spring goes, the speeds most often used for meticulous stitching are so slow that I have to wonder if it is another solution for which no problem exists, but they are cheap, so *whatever*.  As we used to say in the shooting sports, if you think it helps, it helps.

-DC

[Gregg From Keystone Sewing]

1 hour ago, SARK9 said:

On the subject of aftermarket parts with wild variations in tolerances, the underside of the needleplate, where the groove which prevents the bobbin case from rotating is located, also deserves a look. I've had to increase the width slightly and ease/reshape sharp edges to allow the thread to pass smoothly without random binding or erratic tension. Also, if your hook timing is slightly retarded, you may get a momentary high tension on the needle thread as it slides across the top going around the bobbin case. This might tend to allow the thread to pop into that groove over the bobbin tension spring and wreck things. Slightly too much hook advance is less risky, within reason, and worth a try if you hear "snapping" noises as the stitches form.  As far as the cheap and variable aftermarket bobbins leaving too much gap, I submit that the "sideless" prewound bobbins leave one hell of a gap as they are unwound and used up without issue in many commercial applications. I personally only use them with certain common colors in *G* style bobbins on a Singer 111W152 which is dedicated as a binding machine, so who knows. The sideless bobbins are very uniformly wound and hold a bit more thread. As far as the anti-backlash spring goes, the speeds most often used for meticulous stitching are so slow that I have to wonder if it is another solution for which no problem exists, but they are cheap, so *whatever*.  As we used to say in the shooting sports, if you think it helps, it helps.

-DC

You have no idea how much great information you just gave me to bounce off of.  Needle plate to hook height can be an issue as well as burs.  The LU-1508 Engineers manual will cover this.

As for hook timing, this is how you do it on an LU-563; set the stitch length to zero, move the needle up 2.3mm from bottom dead center, moving the hand wheel counter clockwise until the hook point is center line with needle, your hook timing is now set.  Your not just timing the hook to needle thread pick up; you are also timing when the hook will release the thread to start to form a loop.  1% off from this is 1% away from the ideal machine setup, even if you've exhausted all other options and settings.  Even then something else is likely wrong.  The timing is the timing, until it's no longer the timing I guess we can say.  If this is set incorrectly, yes, for sure you may hear the thread snapping across the top of the hook as it tries to release.  Perfect example.

Here comes the best part, I understand and agree 100% about what you say with pre wound bobbins.  Some people have experience with pre wound bobbins only,  like embroiderers.  Most embroidery machines do not even have a bobbin winder.  Some sewers have only seen metal, and some mix and match.  Without going into the benefits and perks of using steel vs pre wound bobbins, they both can provide sewing issues that can be vastly different from one another, even if the machine is 100% tip top.  Pre wound bobbins are not going to unravel as the thread tends to stick to itself as part of the manufacturing process and tend to be lightweight.   In contrast a metal bobbin wound with a polyester or synthetic made PTFE thread wants to kink up and unravel by nature.  The only example that I can think of and just made up on the fly here is that if you take both of them and fling them across a room, the pre wound will maybe get a foot or two, where you send a metal bobbin to the other side of the room and out the door.  Big difference when sitting in the bobbin case as you sew along.  One other thing to consider is that with a fully threaded steel bobbin, many electronically controlled machines with needle positioning, the hook tends to come to very quick starts and stops when in use.  This is why if you check out many model machines that are plain mechanical and then available full function, they often have two different part number bobbins.  One is steel, the other aluminum.  Keep the weight down and prevents over spinning.  Add in an anti back lash spring and there's not much else that can be done that I can think of.  Hope this give some things to think about and thanks to DC for the excellent lead in.

Edited July 6, 2019 by Gregg From Keystone Sewing