LU562/563 Class stitch length (question for Uwe?)

[mixmkr]

Uwe....following your [most] excellent YouTube on the LU563 Class adjustments, I [gleefully] adjusted my stitch length out to about 8mm or 3 stitches/inch.  Previously it had been much less....about 5mm.   Seems to be working just fine.

I went to the max, and then dialed back just a tad, so I wasn't at the extreme limit.  For some reason, ONLY with material being sewn, the forward/reverse bar was slightly moving, but I could not see or hear anything that was hitting.  Free wheeling the machine all was OK.  But  "dialing back" just a small amount, totally eliminated this movement.  Like I said, the handle ONLY moved with material being sewn, not freewheeling.   Forward and reverse are matched up too.  (btw, I'm guessing that the machine had had these limits set for YEARS and with further lubrication and use, will adjust to the longer stitch length as the lever feels a little "gummed up" at the extreme ends now...PAST where it used to be.  NOT hitting anything, but just a little stiff)

My questions are:
1.  Why would there be a 2nd limit (end stops) underneath the machine?  Also, this little bar would have to be "ground out" at the limits, to let the machine do its' 8mm stitch.  The limit bar seems to allow a max of about 6mm.  For some reason, I have this "fear" about removing [safety?} features or something that was originally installed on such a nice machine.  Obviously the adjustments on the outside...on the side of the machine do the trick, but is there ANY way should that fail, that the machine could damage itself without these limit restrictors in play?

2. Running the machine at a decent speed, now with the increased stitch length, can anyone see a reason why this could be harmful?  Basically the forward/reverse lever has no restrictions now, but after careful inspection, I'm not see what might happen to create any damage.

I guess this is just like a early Christmas present to me.  I had wanted a longer stitch length out of my JUKI LU562, and this magically IS the trick.  Almost too good to be true.  Totally makes this a "new" machine.   But admittedly being fairly new to the machine (I've only tinkered with it for about 2 years now), I don't want to wander into territory I shouldn't go in and do something regrettable.

 

Uwe...again...wonderful vids and THANKS.    Hopefully you or others could weigh in on my concerns in my questions above.

 

[mixmkr]

BTW, here is the link to Uwe's vid, if others haven't seen it.  VERY well done and highly recommended for "learners" such as myself.

 

Edited December 22, 2016 by mixmkr

[mixmkr]

One other question...

If you didn't care about matching up reverse and forward stitch lengths.... I suppose you could increase the forward stitch length, sacrificing the length of reverse?

[keithski122]

I had the same problem with the reverse lever moving on a juki 563.In the end it was easily fixed by adjusting the stop for the lever so it was held slightly down.

 

[mixmkr]

Thx Keith.  Yes I saw that thread and re-reading after watching Uwe's vid, it makes more sense.  I find that dialing back the stitch length, which is probably basically the same as decreasing the limit on the stop, solves it for me.  To the point I'm not really even seeing a shorter stitch length, because I'm only dialing back just the smallest amount.
Keith...did you remove the 2nd stop on the underneath of the machine?   I found that to leave it on, I would have to grind the end (opposite of the set screw w/lock nut), to get my 8mm length.  Otherwise the stop would limit the stitch to about 6mm or so.  I may do the grinding, if I feel so compelled to put that stop back on.  Uwe's vid indicates it's redundant.

[Uwe]

I think the lower limiting bracket is indeed redundant on the Juki LU-562/563 models and is of little use to the hobbyist/craft user. From what I have seen, there's nothing the lower limiting bracket can do, that you cannot also do with the upper limiting adjustments. The Juki design actually has three ways to set stitch length: the excenter that creates the feed motion (with the clunky press-a-button-then-turn-the-hand-wheel adjustment), the reverse limiting bracket underneath, and the upper reverse limiting adjustments. You could, theoretically, set the excenter to generate max feed motion motion all the time and then regulate stitch length by holding the reverse lever in a precise position. Other designs (e.g. Consew 206RB5) do exactly that, the excenter always produces full feed movement, and that full movement is then regulated by adjusting the reverse lever position via the stitch length dial mechanism (on those designs you can see the reverse lever move up and down as you adjust the stitch length.) 

Many industrial machines have features designed for a factory setting with a few trained mechanics supporting dozens or hundreds of operators who are trained to sew, but not trained to adjust the machine they operate.

The main purpose for the secondary limit device on the underside is likely to give the mechanic in the factory the option to limit the range of stitch length adjustments that the operator has access to (after removing the button that holds the excenter). Factories often are very controlled environments and only the mechanic is allowed to adjust the machine. Certain adjustments are locked out somehow (e.g remove a button or prevent the machine from being tilted back.) The mechanic may set up a machine to perform one specific sewing operation perfectly with a special feed dog and throat plate that have a smaller range of motion than what the machine is capable of. The mechanic then doesn't want the operator of the machine to accidentally/maliciously dial in a stitch length that is too long and damage the special parts (e.g feed dog hitting the front or back of the smaller throat plate opening). In that example it makes sense to limit the stitch length adjustment with the bracket underneath and then allow the operator only to make the stitch length shorter, but not longer than pre-set, locked-in limits underneath.

The hobbyist or craft shop user is frequently both mechanic and operator. In some cases that full access to all adjustments amounts to a loaded gun pointing at their foot.

When adjusting a machine to operate at its design limit or slightly beyond, it's always wise to very carefully check movements and range of motions with slow, belt-off, hand-turned stitches to make sure nothing binds or touches that shouldn't. Crane your neck and use a small dental mirror to see parts of the machine not easily visible from the normal vantage point. While sewing, pay close attention to how the machine sounds, too. The moment the machine starts making strange noises, stop and find out why. Sewing at full speed while blasting death metal music may shorten the sewing machine's life expectancy.

I contemplated showing how to purposely unbalance the reverse mechanism to maximize forward stitch length in the video, but visions of irate folks blaming me for luring them into breaking their machines made me leave that part out. On my machine I could unbalance the reverse mechanism so much that it was touching the casting on the underside in a very hard to see spot, making the reverse lever bob up and down while sewing.

If you're a careful, methodical person, then I think it's fine to adjust your machine close to the limits like you did.

[mixmkr]

Thx Uwe, much appreciated.  Merry Christmas!  :-)

[Djslickd]

Sorry to tack on to this old topic, but I can’t get the forward and reverse stitching to balance on my New to me Juki LU-562. I followed your video Uwe, and I found that removing the screw and trying to move the block down to limit the forward stitch just moved the entire assembly. It seems to be frozen. I tried a few ways to free it, machine oil, some light prying with screw drivers, but I’m afraid I would damage something with any more force. I could try some PB BLASTER, but I’m not sure how bad this would be for the machine or not.

 

Im trying to get my back stitches to go back into the previous holes for some quality looking stitching in leather bags, and this is giving me fits.

 

Any advice would be much appreciated. Not sure about any techs in the Milwaukee, WI area, but being on a tight budget I was hoping to fix it myself.

 

Thanks!

Dave

[Pintodeluxe]

The reverse mechanism can be limited by two different mechanisms.  One is external to the right of the reverse lever.  The other is underneath the machine, a stop limiting travel of the block.  Make sure neither is limiting travel as you make the adjustment.