Juki Lu-563 Issue or is it?

[Rossr]

Hi folks,

 

Recently I started to really go over the flat bed machines I have.   First attacked the singer 111 W 155.   Sewed ok but always seemed to have some tension issues.  After much reading of posts on here, some google searches, and the manual.  It is now nicely adjusted and the tension  is able to be adjusted easily.  So with this in mind we attacked the Juki.  There has always been some jerking to it and it sewed ok and the tension was ok.  But upon closer study we learned that it should be much better.   So After much research and study of the machine we  think we found the issue but not sure what to do about it.  Please see attached video.   

 

Our first realization was the needle was jerking a bit and the tension spring that holds the thread up on the top seemed to jerk twice.  In the video you can hear it click.  IF you watch closely you can see the first click and catch and then a second one happening.  Both times it seems to catch on the little tabby thing(Highly technical term there, if you need to pause to look it up I understand)  that is sticking under the pressor foot plate.  The thread gets very tight at those two points causing the jerking.  Upon study of the singer.  This does not happen and it delightfully slides across and up to complete the stitch. 

So not sure what to do with it.  Myself and father are working on it.  Both of us are mechanical He is very Mechanical.   Sewing machines are new to us though so its   a learning curve.  Hoping someone knows of an adjustment we have'nt seen or understood.   or is it an issue of something needing to be filed down?

 

 

https://www.facebook.com/EinhornLLC/videos/1024171401054561/

 

[Rossr]

An additional note. The singer is using 69 thread size.  The juki in video is 138

[Rossr]

I used 69 thread and it still catches a little.  Surprisingly using a 24 needle(i didnt change it out) it sewed pretty tight.  I then changed it to 92 thread for sure catches with that size. I used a size 20 needle and its seemed to sew pretty well....just trying to add as much data as possible

 

Thanks

 

Ross

[SARK9]

If its not the bobbin case opener not moving the case far enough, check your timing. Sounds like it may be slightly retarded....the thread passing around the bobbin case may need to get past the centerline of the hook assembly slightly sooner, and it will miss or slide off the hook gib more easily if so. 

 

-DC

Edited January 27, 2018 by SARK9

[Uwe]

The bobbin case opener finger on the machine in the video above is not adjusted properly and does not perform the task it's supposed to. That's why the thread snags on the tab.

I made a video recently for a different topic related to bind conditions using my Juki LS-341(different machine, but same hook and bobbin case opener functionality.) The first half of my video shows how that bobbin case opener finger should be adjusted and how it moves the tab. Perhaps it can clarify a few things. 

The way you adjust the bobbin case opener finger is a little different on a Juki LU-563, but the same concept applies.

Here's a video from my archive that shows a 563 class machine after I made some adjustments (unrelated to the bobbin case opener.,) It shows how the finger pulls back the bobbin case from a different angle.

 

Edited January 27, 2018 by Uwe

[SARK9]

I didn't notice the video of the machine he posted at first go (oops) ....and the first snap is for sure the case opener adjustment. However, the *second snap* was what got my attention, since I had just finished correcting an identical defect on the relic machine I am working on at the moment, and I wondered if his machine was similarly afflicted.

There were two causes for a second snag or snap after the thread cleared the notch/tab on my old castoff machine, and the primary cause was: The rotational position of the hook assembly placed the trailing edge of the *hook gib* in the path of the rising thread just long enough for it hang on its sharp outer corner, allowing it to tense up and snap when released as the hook rotated past the breakover point. I could see the point where it was hanging on the old derelict hook of this 111W152, and my first thought was to blend and polish the gib's trailing edge to allow the thread to slip over it smoothly. 

--> If you look closely at your video of the Tacsew 563 clone, you will see someone has given this treatment to the leading and trailing edges of the hook gib on that machine. <-- 

I had just timed this machine by the numbers (now that I can actually clamp the needle bar!), and it still had this brief hang-up, so I wrote it off to additive tolerances in the poor old thing and advanced the timing very slightly...that cured it instantly, and still seems to form stitches normally. Another post-tab snap on my junker was caused by the sharp edges of the needle hole on the underside of an after-market feed dog...it was reluctant to pass the knot/loop with heavier thread and caused a inconsistent tension issue plus an audible snapping hesitation with each stitch. Those are some other snapping issues on vertical axis machines I thought might be worth a look.

-DC

[Rossr]

@SARK9 @Uwe  Guys these are both some great insights. I didnt have time to spend on it today. But I am hoping to find time in the afternoon tomorrow. I will let you know how I a fair. Thanks for the time and advice

 

Ross

[Rossr]

Ok so much improvement thanks to the suggestions above.  the last catch you can see in the photo here and also video. 

The picture you can see the blue thread is actually behind the square part there.  This doesnt always do that but it does it enough....I almost feel this is a timing issue and I need to some how change the travel on that coming around?  Current video also shows it to some extent.  That beind said tension is able to be adjusted and its laying a nice stitch pretty even with the leather front and back, 

 

https://www.facebook.com/EinhornLLC/videos/1026374677500900/

 

[Uwe]

It looks to me like your hook timing is about "five minutes" too late. On machines with this vertical axis hook design, the hook timing criteria can be generalized like this:

When the needle is in the bottom dead center (BDC) position, the tip of the hook needs to be at the 7 o'clock position.

I superimposed a still frame of your video with a clock face to illustrate the concept. Your hook tip represents the Minute hand on that clock.

On your machine the hook is about five minutes too late, i.e. hook tip points at 6 o'clock instead of at 7 o'clock when the needle is at BDC.

I recommend advancing the hook timing clock-wise by "five minutes."

After advancing the hook, you may also have to adjust needle bar height up a little to make the hook tip pass the needle near the lower third of the scarf.

I think you will find that the other issues like thread snapping around the hook, then catching on the release finger, then snagging on the rectangular hook gib below will all improve as a result of the hook advancement. 

 

Edited January 30, 2018 by Uwe

[Rossr]

39 minutes ago, Uwe said:

It looks to me like your hook timing is about "five minutes" too late. On machines with this vertical axis hook design, the hook timing criteria can be generalized like this:

When the needle is in the bottom dead center (BDC) position, the tip of the hook needs to be at the 7 o'clock position.

I superimposed a still frame of your video with a clock face to illustrate the concept. Your hook tip represents the Minute hand on that clock.

On your machine the hook is about five minutes too late, i.e. hook tip points at 6 o'clock instead of at 7 o'clock when the needle is at BDC.

I recommend advancing the hook timing clock-wise by "five minutes." You may also have to adjust needle bar height up a little to make the hook tip pass the needle in the lower third of the scarf.

I think you will find that the other issues like thread snapping around the hook, then catching on the release finger, then snagging on the rectangular hook gib below will all improve as a result of the hook advancement. 

 

Uwe,   That is great visual and thank you for getting me an understanding of proper names of the parts too.  I dont like calling things the round thing or square item.   Upon some research i found a a video you made about a Consew 225.  In the interest of understanding for others too.I gather the process is the same on the juki lu 563?  Here is that link,starting about 4:50minute mark.

 

Ross

 

[Rossr]

Sorry this is the 225 video starting at the 4:50 mark for this application I think.   The above video I had used previous and owe thanks to uwe as well.   It corrected some issues I had. Uwe these videos you have made are top notch!

 

[Rossr]

Ok folks so I think we got it Here's a picture of front and back stitch. Blue is the top and black thread is the bottom stitch,  and I have also attached a video.  You will notice no more snaps or catches!!!  We did have to do some fixing of the needle and hook timing too but it all worked out and learned an awful lot about the machine in the process.  I cant thank you guys enough for sharing information. 

IF you guys notice anything else by all means say so but I think over all its a winner

 

https://www.facebook.com/EinhornLLC/videos/1026374677500900/

 

Thanks everyone

 

Ross