Juki LU-563 Hook height adjustment

[JukiLU563]

Hi all.

Thanks for letting me join. I have read many posts on this site and have been very impressed with how helpful everyone is, and the awesome projects I have seen.

I have had my Juki LU-563 for a few years, but just now started to use it. After much work on adjusting, cleaning and fixing things, it seems the gap between the bobbin case catch tab, and the foot plate does not have large enough gap for the thread to pass between easily (I measured .18 should be .40 per an engineering manual I found). I also believe the top of the bobbin is too close to the other cover/plate to allow the thread to pass over it well either.

Well after reading many posts , and watching many videos over the last week, I have learned a lot!  I corrected the top threading route so not be around the tension disc pin, took apart and cleaned the tension discs, I know for sure how the needle goes in, how close the hook should be to the needle, timing, oiled everything, cleaned many things.

I took the hook out and it looks to me like the brass bushing should be lower about .5mm the amount I need to make the 1mm(.40) gap at the tab/plate area. I took the hook out, loosed the bushing set screws and gave it a few taps to drive it down, but no change.

If the bushing #6 won't move, then would I need to remove or replace with a thinner #25 thrust washer? I am afraid to let the gear #22 slip out as I understand it is hard to get back in? I did mark it and the drive gear #20 with nail polish to match up teeth should something happen. The rod between the hook and bobbin case lever #5 even sits high above #8 about the amount I need it to move down. However #5 seems to set flush on top of the bushing #6 just fine.

Anyone else have this issue too? Thanks.

[chrisash]

First thing to check is the actual bobbin, they come in all small variances in size depending who made them, College sewing give three sizes of width versions, maybe yours are just to tall, worth investigating simple things first. also Hooks are available from many different makes and not all have the same tolerance's

Edited January 27, 2022 by chrisash

[ThomasA]

On 1/27/2022 at 10:30 AM, chrisash said:

College sewing give three sizes of width versions

Interesting, I have questions on the same topic. I realize hook assemblies differ in the details, but are they offered in three width versions? Width of the locating tab? Or the height of it? Anyway, I looked at Collages web shop but could not find it.

In this context I'm looking at the hook locating grove on the throat plate. Both height and width of the grove varies a lot between the throat plates I have. The clearance provided in height with six different throat plates (combined with one of the hooks) varies between 0.83 and 1.38 mm. That's more than the tolerance for one adjustment of the hook height, but if you measure the width of the grove, it varies even more - 0.52 to 1,70 mm. The thread is supposed to pass here so if 1 mm is needed on the top, 2 millimeters would be logical on the sides as the thread passes on both sides of the tab simultaneously - but that does not seem to be the case as most throat plates I have has a measurement on the lower side - less than one mm total clearance measured on one side of the tab. This is obviously dependent of the width of the locating tab of the hook assembly ut it is measured with the B1830-563-BA0 assembly for "extremely" thick thread - it should give clearance for that one could think. (It's tab is 3,70 mm wide half way out on the tab - where it meets the grove.)

So my question is, when I go down to the machine shop to finish my attachments, what dimensions should I aim for? Is there a downside to having too much clearance? One manual says something like "The hook should be high enough to stop the rotation and low enough to pass the thread".  That's up and down (no measurement needed), but nothing about sideways.  I've looked for specifications or drawings of this stuff, but it seems to be rare. Can anyone fill in some of the blanks?

[shoepatcher]

You take the feet, feed dog and throat plate off the machine so only the needle and the hook are left.  This allows you to time the hook to the needle by hand.  The hook should be very close to the needle  without touching it.  I believe you go to bottom dead center with the needle and then up 3/32" and needle should be timed  at that point.  Distance of hook point from needle should be about the width of a paper  business card.  Keep in mind the needle deflector will push needle from left to right before hook arrives. I also tell people to deepen the slot on the underside of the throat plate a few thousands so that #138  thread can pass freely over the bobbin case finger.  Buffing the slot will also let thread pass more easily in the slot. 

glenn

[ThomasA]

Tanks Glenn! Could you perhaps give me a sample of bobbin case finger widths? I have one that is 3.40 mm (.134") and another one that is tapering, but 3.70 mm (.146") where it meets the throat plate grove. I'm hesitating to grind it down to match the narrower one... Because its expensive, and even though the narrower one works I would rather know what I'm doing and aim for standard dimensions...

[shoepatcher]

They vary from hook mfg. to hook mfg.    The finger on my Juki 1508 is .134" width.  that is a genuine Juki hook.  I think the hooks were the same on both the 1508 and 563.  The use the same bobbin.  I usually round the edges of the finger slot on the underside of the throat plate and buff it so the thread will go in and around it without any hinderance.  

glenn

[ThomasA]

OK, nice to have .134” confirmed! My old hook kit, with that finger width, came in my Lu-563 but is probably a B1830-521-0A0 with encased bobbin. That type normally comes in double needle machines like LUH-521 and LU-1565. Fits well in a 563, but it’s a bit tedious to change the bobbin. Don’t know what the pros are? Anyway, I will now make the B1830-563-BA0 finger have the same width.