Tacsew/juki 563 Hook Timing Problem: Stitch Length Affects Timing

[Uwe]

I'm working on my Tacsew T1563 (a Juki 563 clone) and I'm stumped. I adjusted hook timing the way I normally do on this class of machine with stitch length set to zero (or very small). The problem is that hook timing changes as I'm increasing the stitch length. Something else must be off, but I can't quite figure out what. It seems to me the feed dog and needle are too far towards the back by the time the needle gets there.

One step I didn't (or rather couldn't) do is verify proper top/bottom shaft synchronization. My machine does not have the usual two opposing arrows on the underside that line up when the thread take-up arm is in the top position to indicate proper top/bottom synchronization via the timing belt. There IS a mark on the shaft collar, but nothing to indicate where it should be pointing to.

Is there a way to verify proper top/bottom synchronization without those two opposing arrows?

I've not changed the timing belt position on this machine and I'd rather not mess with it unless I have to. The timing belt does look brand new, however, so perhaps whoever replaced didn't quite get the synchronization right. I'm not even sure that a timing belt that's off by a tooth or so could cause this apparent hook timing shift when changing stitch length.

Here's what my machine looks like underneath where the arrows normally are. The picture was taken with the thread take-up arm in the top position:

Here's a little video of the hook area that hopefully illustrates what I'm talking about:

Edited January 20, 2016 by Uwe

[CowboyBob]

When your @ o-stitch length the feed dog needs to be centered (front to back) yours is too far back.

[Uwe]

I don't quite understand what you mean, Bob. Are you saying the feed dog (and needle) are too far back and need to come forward?

I'm not sure that's possible. I took some additional video from a different angle with the throat plate installed. At Max stitch length the feed dog is nearly touching the throat plate opening at the front, so I don't think I can adjust things toward the front. The Max front/back movement does appear to be centered around the 0-length position of the needle.

It does seem to me that front/back and up/down movements are not properly timed. It's like the needle+feed-dog start moving backwards too soon. The needle comes up towards the end of the feed movement instead of the middle to meet the hook at the same center position.

Here's an extended version of the video with the additional angle added on at the 40-second mark:

Edited January 21, 2016 by Uwe

[gottaknow]

It appears to me your top and bottom shafts aren't synchronized. The feed motion for both the needle bar and feed dogs was moved to the front to get it to sew at all. If I were to speculate, your top shaft is advanced a tooth or two. Hard to say without seeing it in person. Until you get synchronized, it won't sew right no matter what else you do. When you get that figured out, you should be able to center everything on 0 spi, adjust your spi to max and still be in time. I've seen machines where instead of having a mark on the casting to use for shaft timing, but rather a "position", like 6 o'clock for example. May the force be with you.

Regards, Eric

[Uwe]

This one's a good learning experience because everything that can be out of adjustment actually was. Oddly enough it actually made stitches when turning it over by hand, but it was very obviously not happy.

The synchronization was definitely off. I moved the timing belt one tooth and it made a big improvement -no more thread snapping around the hook, and the thread slips through all the openings as it should. The timing belt was quite tight, but with a little sauna treatment from a hair dryer it slid off and on the lower gear without trouble. I made some marks with a pen to be able to tell where it was aligned.

The distance between inner and outer presser foot bars was 10.5mm instead of the correct 8.5 mm at "0" stitch length, a pretty big difference.

I also noticed that the service instructions for this machine (or Juki LU-563 manual, really) call for hook timing to be adjusted when stitch length is set to 1/8" instead of "0". This is different from all the other machines I've worked on so far.

I'm still fighting with getting thread tension to work properly. The replacement thread tension unit I had ordered is really crappy (and I ordered three of these - argh!), although I'm not positive it's the root cause of the thread tension issues. It seems the knot is not pulled tight in time before the inner presser foot advances forward. On my Consew 225 hook/loop video, I could see the knot being pulled tight into the material before the feed dog advanced forward and the knot disappeared behind the feed dog hole. On this one, the still-loose knot disappears behind the feed dog opening and I think this interferes with proper knot-formation. The timing belt may still need a little more tweaking.

I'll work on it some more on Sunday, and make some videos to document progress of lack thereof. Gotta get ready for big photo production on Saturday.

It's still a work in progress, but it has great potential and I have high hopes for making this machine sew with buttery smoothness. It's actually a really nicely done clone. It cleaned up really well, the parts underneath all look shiny and not worn at all. It seems really well put together overall with good workmanship. Alas, it suffered from serious, fixable adjustment issues that caused its previous owner a great deal of grief, no doubt.

Edited January 23, 2016 by Uwe

[TZBrown]

Any progress report Uwe?

I would enjoy a video on the top to bottom shaft timing and the presser foot bar setup

I learn so much and it is a good production

[Uwe]

Not quite yet. I got side-tracked making that binding video on my Adler 205-370.

I just carved a beautiful new white laminated plywood table top for her today and my replacement-replacement thread tension unit should arrive tomorrow. I'll have her mounted in the new table with a new servo motor on Thursday and then I'll check where I stand adjustment-wise.

[Uwe]

Some progress and a little detour. I installed the machine in a new tabletop, installed the new thread tension unit today and added a servo motor. A normal person would have started to sew, but my foot lift tension release was not working properly and next thing you know:

But I did confirm that one suspect part was indeed broken:

The little finger that sticks up to align things had broken off.

This is what the part is supposed to look like:

The new part is on order and I hope it arrives before I forget how to put things back together.

Here are a few shots of the two different replacement thread tension units I had ordered. The one with the grey plastic knob on the right is a little better than the one on the left, but not because of the bigger knob:

What irritated me about the first one received was the significant offset between the two sets of discs. Ideally the two disc sets would align to let the thread go from one to the other smoothly. This design had a really big ball of sorts to attach the tension disc post to the plate. It pushes the tension discs away from the base plate and makes for a large offset. On the original tension units the discs are basically right against the plate (but it was totally broken, so it did me no good).

The second unit I got was a little better in that respect:

I'm dismayed that there is no service manual available for this particular machine. I suspect it's a LU-563N copy. The LU563N was the successor to the LU-563, and it was a transitional design that incorporated some design elements that would also show up in the next big overhaul, the LU-1508.

I found a parts diagram for the Juki LU-563N which is indeed closest to my Tacsew T1563 clone. Unfortunately, I'm striking out finding a copy of the service/engineer manual for the Juki LU-563N.

The problem is that key adjustment procedures like timing belt synchronization, hook timing details, presser foot timing, etc. for the LU-563 and the LU-1508 are totally different, and I'm left to guess and trial/error my way to what actually works on my machine.

The adventure continues . . .

Edited January 29, 2016 by Uwe

[dikman]

C'mon, admit it, Uwe, blundering around in the dark is good fun .

[TinkerTailor]

It looks like that ball is just a rubber o-ring and someone at the factory got the wrong one. A thinner o-ring of the same diameter would fix it.

C'mon, admit it, Uwe, blundering around in the dark is good fun .

I restored my first treadle fabric machine in a cabin without power, and wood heat. Does that count?

Edited January 29, 2016 by TinkerTailor

[Gregg From Keystone Sewing]

1st things first, we really need to go in and replace the broken tension release slide.

After that, I'll bet someone here $1.00 I know what the issue is here with the needle bar frame feed dog hook thing. Seeing the video at 1:26 you can clearly see from the side the needle playing catch up.

View attached image, then remove the gib, turn this over by hand and you'll see this problem disappear. If so, this means the gib is too tight. It can take a few tries to get this set correctly.

On the longest stitch length setting, we set this by putting sewing oil all around the contact point between the gib and rock frame. When the gib is set correctly, you should be able to see an oil ooze out from around the gib with no real feel of side to side play by hand as the frame sweeps front to back. If you don't see this it means the gib is too tight, and is going to lock up and have to play catch up with the feed.

Hope this helps!!

Edited January 29, 2016 by Gregg From Keystone Sewing

[Uwe]

I certainly do enjoy blundering around in the dark, especially if the person I'm blundering with has great timing and knows how to adjust tension just so.

@TinkerTailor: it sure looks like a rubber O-ring but it's actually metal and part of the threaded post. Not sure if it's a manufacturing or a design issue. I suppose I could just use a dremel and grind down the bulging ring:

@ Gregg: Thanks for that suggestion. I checked that guide gib part on my machine and it appears to be doing exactly what it's supposed to.

I actually made a good deal of progress this morning. I decided to put things together but leave out the broken thread release part. It's not exactly a vital organ and I can't see any reason why the machine should not function properly without it in place. I'll deal with the foot-up thread release manually, not a big deal.

As I was putting things back together, I adjusted foot lift, timing of the inner presser foot (so it arrives at the material at the same time as the needle - it was way early before), re-timed the hook about four times with different top-bottom timing belt settings. Once I have it all figured out and can reproduce it reliably, I may make a little video showing how I made these adjustments.

The machine actually makes a very nice, even stitch now, so I' think I'm about 90% there. The one thing that's still bothering me is that the thread seems tight wrapping around the bobbin and it snaps a little as it's being released from the thread cast-off nib on the hook (i cleaned and polished the nib, no burrs or anything).

So it seems to me that I'm still just a little off on the timing to reach the buttery smoothness nirvana, but I'm not quite sure which adjustment will get me there. Should I advance hook timing a little or is this still due to an imperfect top-bottom timing belt position? I can't be far off.

Here's a little video that hopefully shows what I'm talking about:

[dikman]

I've only just learned about timing of the inner foot (is there no end to learning with these machines?). I'm pretty sure that was why I snapped two needles in the Pfaff, the needle was reaching the leather way before the inner foot, and I'm pretty sure it was causing the needle to deflect. In the process of adjusting it I managed to get the needle/foot to run in reverse .

Sounds like you're almost there, Uwe.

[Uwe]

All better now. I took the timing belt off one more time and advanced the bottom hook drive shaft one notch. Then I re-timed the hook for the seventh time today - I'm getting the hang of it.

Here she is sewing as well as I had hoped for:

I'm gonna give her (and me) a rest before I tackle that confounding reverse mechanism to balance forward and reverse stitch length.

[TZBrown]

It's looking real good. It is amazing what 1 cog on the timing belt can do, subtle change, dramatic result.

That's why I enjoy the search for perfection with these machines, and it is rewarding, at least to me