Set up of Juki LS-1341 type machine

[palvim]

I also notice that when the bobbin case opener is put in the right place more or less the machine jams somewhere and I can't rotate the flywheel further. Is the bobbin case installed wrongly? 

 

 

[Wizcrafts]

For the time being, I would back off the position of the case opener until the hook turns freely. There could be some thread or other debris caught in the gears that drive the hook. Or, the opener might be pulling back too far. It only needs to make a slight movement on the bobbin case so that the top thread clears the tab.

[palvim]

I've more or less got the machine to be where it was before. 

Hook timing seems to be ok

Bobbin case opener a little better. 

But the same problem persists. 

I'm really curious if all parts that are listed in the parts manual need to be for 1341 to use the 1341 hook? Could it be that the machine actually is a 1341 but just has the wrong hook? The company specifications says the following. 

 

Cylindrical lockstitch machine with compound transport and high walking foot. The model is destined for medium and heavy sewing. Compound transport, large stroke of needle bar and foot lifting to 16 mm facilitate technical sewing. The hook is larger about 30% and it is especially useful in case of technical sewing with thick threads. The diameter of cylinder is 72 mm. There is energy-saving motor which saves even 70% of energy.

For this model of machine JUKI parts are suitable.

We offer assembled, ready to work set including:

head, motor, top table and stand, a drawer, additional accessories, operating manual

Technical parameters

Type of stitch	Flat lockstitch
Type of transport	compound
Direct drive	no
Maximum length of stitch	9 mm
Maximum speed	2000 spm
Maximum foot lifting	16 mm
Stroke of needle	36 mm
Size of hook	enlarged
Lubrication	open
System of lubrication	manual
Automatic needle positioning	no
Automatic thread cutting	no
Automatic foot lifting	no
Automatic bartacking	no
Automatic walking foot	no
Automatic wiper	no
Automatic nipper	no
Control panel	no
System of needle	DPx17
Thickness of thread	#10
Clearance under arm	260 mm
Built-in LED lamp	no
Controlled by smartphone	no

 

 

[DonInReno]

How interesting this problem has become!

We don’t know exactly what kind of machine this is.

We don’t know what size thread it’s designed to sew.

We don’t know what’s binding up the hook.

We still don’t know what is causing the original tension issue, although it’s probably related to the hook binding up.

I’d say you should find a repair shop to clear the hook, then get the machine to sew correctly with thinner thread, before trying to do anything more with thick thread.    The hook has to be completely cleared of what’s jammed it up. 

[palvim]

I guess that's the right thing to do now. It seems we've tried enough. Now let the repair shop try. I'll be going the week after next. I'll update here. But I really hope this machine can handle 135 thread easily otherwise, I'll ask them to order the parts for the 1341 machine and install that. I counted from the parts manual and it's about 13 parts. 

I can say enough how grateful I am for all the help I've received so far. Thank you. 

[DonInReno]

Hopefully it’s an easy fix and you’re up and sewing soon!

[chrisash]

Get a fixed quote prior to giving them a fee hand to upgrade, I would just ask them to do there testing after repair on the 138 thread before mentioning any upgrade

 

[Uwe]

I still think you should try to advance hook timing. It may make a big difference. After my previous recommendation, you just said hook timing looked fine as it was. What I’m a asking you to do is to purposely advance hook timing away from that “fine” adjustment. You may just end up with a “perfect” adjustment. On occasion, the by-the-book setting is just the starting point. Then you make small adjustments until everything works smoothly - I do this quite often. Picking up the top thread loop is only one of the functions the hook timing tries to get right. There are several other functions that are also affected by hook timing. To get all of them working just right at the same time, you may have to vary slightly from the original adjustment.

Don’t view the adjustments shown in the Juki engineer’s manual as absolute commandments. Your machine is a copy and it uses a different hook. Some adjustments may simply be a little different for your machine.

That change-over to the 1341 configuration you’re contemplating seems like a major undertaking, one I personally would be very reluctant to sign up for. I’m not sure it will be worth the money you’ll spend to have a mechanic do all that work. It’s like accidentally buying a car with a manual transmission, then asking the dealership to install an automatic transmission. While technically possible, it’s not an economical solution. It’s generally far cheaper and better to trade the manual car for an automatic one (or learn to drive a manual.)

Edited April 24, 2021 by Uwe

[palvim]

Hi Uwe,

I will not do an upgrade of the hook system. I guess in that case I'll have to sell the machine. However, I have advanced the hook timing and it definitely is stitching better. When I stitch straight I'm getting a very consistent stitch. 

On curves where I turn the flywheel by hand, the stitch gets all wonky. I am guessing this time it's the man behind the machine that is the problem. Is there a specific technique to do turns and sharp corners without missing the tensions? 

[Uwe]

For turning corners, I recommend stopping the machine with the needle in the material, ideally right after the needle enters the material and well before it reaches the very bottom of its movement. There’s some bad advice floating around on this subject.

Also, lift the feet just enough to pivot the material, but not so high that the thread tension release activates.