Juki LU-563N Snagging thread

[Average]

Hello, 

I am new to this forum, but have been using it as my main resource since purchasing a used Juki LU-563N a while ago from auction.  The machine's timing was very out and I have spent many hours making adjustments and fine tuning to where the machine works near perfect.  Unfortunately I am still having an issue where the thread is getting stuck under the hook and the machine breaks the thread.  It happens usually on the second rotation and creates a real mess of thread on the bobbin side of my project.  I have reached out to Juki directly for the engineers manual, confirmed the timing is accurate and set the thread tension correctly. I'm using a #69 thread and size 21 needle.

 

I have attached a photo of the thread bind I am experiencing, the green circle shows the path it takes before the machine binds and breaks the thread.

 

After spending lots of time researching this forum on my machine I came across this thread https://leatherworker.net/forum/topic/80732-juki-563-not-enough-tension/

And notices the different styles of Hook's.  My machine has the has the B1830-563-BA0 Hook (heavy thread) without the little finger.

I believe this little finger might be the missing piece to my puzzle, it looks like it would prevent the thread from getting trapped under the hook and I'm using fairly light thread so the lighter hook assembly should work better.

I was hoping I could get some advise on the next steps to get my machine running smoothly again. I was hoping I could order just the little "Hook Gib" Part but it looks like there are other part changes between these style hooks.

The part B1830-563-0A0 sells for around $300 from my Juki dealer, But I have also found cheaper alternatives online (replica parts)

 

Could this little hook gib be my problem or should I go about replacing the entire hook assembly?  Any insight is greatly appreciated as I am at a stand still in this repair and I'd like to get sewing again.

 

Thank you, 

Sean

 

[Uwe]

You may just need to adjust hook timing a little to make sure the take-up lever and the hook don’t fight each other over the thread. I remember having a machine that would snag on the end of that hook gib. It’s been a while and I don’t remember all the details, but replacing the hook may not solve your problem.

I think the little finger on the gib of other hook version is mainly there to keep control of the loop a little bit longer as it’s being pulled up by the take-up lever, so that the loop doesn’t get caught again by the tip of the hook as it comes around. Thinner thread tends to flop around more, especially at high sewing speeds. 

As the take-up up lever pulls the thread up, the hook needs to let go of it at just the right moment. If the hook holds on too long, it will interfere with the take-up lever’s job, the thread will snag and cause problems. If the hook lets go of the thread too soon the tip of the hook may catch the too-loose loop a second time and cause a bind.

Most people only focus on the tip of the hook catching the loop when timing the hook. How the hook lets go of the thread on the second go-around is important for a buttery smooth stitch cycle.

I think on my machine I advanced the hook timing a little to make the tip of the hook arrive at the needle a little bit sooner. This, in turn, also lets go of the thread a tiny bit sooner after the thread gets wrapped around the bobbin case.

A short close-up video snippet of a very slow, hand turned stitch cycle would be very useful. Post it to YouTube as non-public and then post the link to it here. It’s the best way to share videos, and the best way to analyze hook timing issues remotely.

I had a Juki LU-563 clone five years ago and installed an aftermarket “BA0” thick-thread version of the hook. I had trouble timing it correctly but eventually got it sorted out. This video shows my hook when timing was retarded (too late). It made a good looking stitch but it made snapping noises because it would let go of the thread too late.

This is the hook timing after I got done adjusting timing. The caption talks about timing belt changes, but I believe now that it really was the advanced hook timing (making the hook arrive earlier at the needle) that made everything come together:

 

Edited January 31, 2021 by Uwe

[Average]

Wow thank you Uwe, Your videos and instructions are definitely the best on the internet, I really appreciate the help.

The change in timing does make sense in solving this issue. I recorded a few clips of the machine so you can see the machine in action. It looks like the thread hangs under the material a little too long, the take up lever maybe not quick enough to take away the slack? Hopefully my videos contain what you are after.

https://youtu.be/pGU9djvwl2s

https://youtu.be/reM8LoyWmJI

 

Best, 

Sean

Edited February 1, 2021 by Average

[DonInReno]

8 hours ago, Average said:

a used Juki LU-563N a while ago from auction.

Since you don’t know the machine’s history, it might be worth while to confirm it has the correct take up lever - the lu-562 lever will physically fit a 563, but it’s a different juki part number.   I notice many aftermarket take up arms are using one part number for both machines, which seems fishy.

[Uwe]

It’s possible that your problem occurs when you stop the machine at precisely the wrong time and the hook moves backwards a tiny bit.

In the video below I show a problem that I had with a Consew 225, which has a very similar hook design to the LU-563, just a bit smaller. If you can purposely make your machine drop the thread in the position shown in the video, then it will probably happen on its own on some occasions.

In the video I show a modification of the hook, which solved the problem, but it probably wasn’t the only way to fix it. I later replace the tab with a full shim ring on that hook and it worked nicely. I’m not saying that you need to modify your hook! 

A small advancement of the hook timing may keep the thread taught enough to prevent the thread from falling. Also, the check spring plays a key role in how taught the thread is when it gets wrapped around the bobbin. 

 

 

[Average]

12 hours ago, Uwe said:

It’s possible that your problem occurs when you stop the machine at precisely the wrong time and the hook moves backwards a tiny bit.

In the video below I show a problem that I had with a Consew 225, which has a very similar hook design to the LU-563, just a bit smaller. If you can purposely make your machine drop the thread in the position shown in the video, then it will probably happen on its own on some occasions.

In the video I show a modification of the hook, which solved the problem, but it probably wasn’t the only way to fix it. I later replace the tab with a full shim ring on that hook and it worked nicely. I’m not saying that you need to modify your hook! 

A small advancement of the hook timing may keep the thread taught enough to prevent the thread from falling. Also, the check spring plays a key role in how taught the thread is when it gets wrapped around the bobbin. 

 

 

Hi Uwe,

I attempted to replicate the thread dropping just as you did in your video, sure enough that is how the thread is falling under the hook, I will adjust the timing this evening in attempt to minimize the slack.

Following your instruction I will retard the timing just slightly to make the tip of the hook arrive at the needle a little bit later, hopefully holding the thread taught and preventing it to drop below the hook. 

Can you elaborate on the full shim ring which you installed on the hook? Maybe with a photo?

Thanks again,

Sean

[Uwe]

I'm thinking the hook timing may need to be advanced instead of retarded, but it's hard to judge without sitting in front of the machine. There's some trial and error involved.

Also, the check spring is an often-ignored, yet key component in this issue. It's supposed to keep just enough tension on the thread as it wraps around the hook and, ideally, take up any slack that may occur.

So while the modification does work, there may be simpler solutions via basic adjustments.

The topic below has the full details for my arbor shim solution and also a neat custom solution by another user on page two. Keep in mind that your hook is slightly larger than the ones we were working on in that topic. Dimensions will vary slightly on your hook.

 

Edited February 1, 2021 by Uwe