Juki LS1341 Troubleshoot

[MerrickTNLL]

Hi all, 

New arrival here having some trouble with a Juki LS1341. The bobbin thread wasnt being picked up so I took the basket out and noticed that the hook wasnt spinning and feels very stiff. The handwheel still turns smoothly but the hook does not turn with it. Ive checked for thread/broken needles, with no luck. I cant actually get the hook out of the machine, it seems to be lodged in pretty tight! Ive watched some fantastic videos by some legendary contributors on the forum (I remember your names from years ago when I first started looking at the machines) but unfortunately havent come to any solid conclusions regarding the issue. 

For context, I bought the machine in great working order 2 years ago and have had it stored in a safe, clean workshop and then at home for the last year. It is absolutely unused since purchase, and was working perfectly before transit (short 2 hour drive). I contacted the seller who has advised to bring it back for repairs, but if I can solve this myself it would be beneficial to my understanding of the machine and hopefully save me some travelling/money. 

I can attach some images if that would be helpful, or upload a short video somewhere and link it? 

Thank you for taking the time to read this. Ill be concise in the future to save time! Cheers, Merrick 

[friquant]

Here's a service manual for the 1341 in case you don't already have one.

Assuming your machine has a hook safety clutch, you'll need to re-engage it. If the handwheel is hard to turn after engaging the safety clutch, you'll need to look for more clues. Disconnect the motor drive belt and remove the needle so the machine can turn as free as possible. Oil the machine, especially the bushings for the hook driving shaft.  Also check that the timing belt is spinning the lower cog. Is the hook stiff to move, or is it colliding with something and coming to an abrupt halt?

As for removing the hook from the machine (if you still find the need to do this), after removing the center screw if the hook does not come out easily soak it in a few drops of diesel or other penetrating oil. I broke the first hook on my pfaff 545 trying to pry it out when it had been dry for years. (Some dried up old lubricant seemed to be sticking it together). Eventually I got the broken pieces out with penetrating oil, a kitchen torch, and some light tapping with a small hammer. Bottom line is, hooks are very hard and brittle so be gentle with it. Good news is, you'll never deform one such that it is out of tolerance

And yes we do like videos and photos 🤩

 

 

[MerrickTNLL]

14 hours ago, friquant said:

Here's a service manual for the 1341 in case you don't already have one.

Assuming your machine has a hook safety clutch, you'll need to re-engage it. If the handwheel is hard to turn after engaging the safety clutch, you'll need to look for more clues. Disconnect the motor drive belt and remove the needle so the machine can turn as free as possible. Oil the machine, especially the bushings for the hook driving shaft.  Also check that the timing belt is spinning the lower cog. Is the hook stiff to move, or is it colliding with something and coming to an abrupt halt?

As for removing the hook from the machine (if you still find the need to do this), after removing the center screw if the hook does not come out easily soak it in a few drops of diesel or other penetrating oil. I broke the first hook on my pfaff 545 trying to pry it out when it had been dry for years. (Some dried up old lubricant seemed to be sticking it together). Eventually I got the broken pieces out with penetrating oil, a kitchen torch, and some light tapping with a small hammer. Bottom line is, hooks are very hard and brittle so be gentle with it. Good news is, you'll never deform one such that it is out of tolerance

And yes we do like videos and photos 🤩

 

 

Thank you so much for your guidance.. I have tried to reengage the safety clutch but nothing is happening to the button as I push the hand wheel back, I can feel a very small amount of feedback but nothing past that, it certainly isn't dropping down as I believe it should? 

This is my first industrial machine (actually my first machine altogether), it might take me a bit of time to troubleshoot, please bear with me! Thank you very much again for your help so far.

[MerrickTNLL]

15 hours ago, friquant said:

Here's a service manual for the 1341 in case you don't already have one.

Assuming your machine has a hook safety clutch, you'll need to re-engage it. If the handwheel is hard to turn after engaging the safety clutch, you'll need to look for more clues. Disconnect the motor drive belt and remove the needle so the machine can turn as free as possible. Oil the machine, especially the bushings for the hook driving shaft.  Also check that the timing belt is spinning the lower cog. Is the hook stiff to move, or is it colliding with something and coming to an abrupt halt?

As for removing the hook from the machine (if you still find the need to do this), after removing the center screw if the hook does not come out easily soak it in a few drops of diesel or other penetrating oil. I broke the first hook on my pfaff 545 trying to pry it out when it had been dry for years. (Some dried up old lubricant seemed to be sticking it together). Eventually I got the broken pieces out with penetrating oil, a kitchen torch, and some light tapping with a small hammer. Bottom line is, hooks are very hard and brittle so be gentle with it. Good news is, you'll never deform one such that it is out of tolerance

And yes we do like videos and photos 🤩

 

 

Thank you so much for your guidance.. I have tried to reengage the safety clutch but nothing is happening to the button as I push the hand wheel back, I can feel a very small amount of feedback but nothing past that, it certainly isn't dropping down as I believe it should? 

This is my first industrial machine (actually my first machine altogether), it might take me a bit of time to troubleshoot, please bear with me! Thank you very much again for your help so far.

[kgg]

19 minutes ago, MerrickTNLL said:

This is my first industrial machine

Can't see the video's with a message of unspported format and MIME type found.

kgg

[MerrickTNLL]

18 minutes ago, kgg said:

Can't see the video's with a message of unspported format and MIME type found.

kgg

Ah okay, ill try to find a suitable file format. Thank you for letting me know. Basically, the handwheeel turns but the drive shaft for the hook is not turning with the rest of the mechanism when viewed from the underside of the machine. Everything else seems in order! 

Cheers, Merrick

[Wizcrafts]

1 minute ago, MerrickTNLL said:

Ah okay, ill try to find a suitable file format. Thank you for letting me know. Basically, the handwheeel turns but the drive shaft for the hook is not turning with the rest of the mechanism when viewed from the underside of the machine. Everything else seems in order! 

Cheers, Merrick

Either the safety clutch has tripped due to a thread jam (most likely), or the driving gears have loosened on the drive shafts.

[MerrickTNLL]

4 minutes ago, Wizcrafts said:

Either the safety clutch has tripped due to a thread jam (most likely), or the driving gears have loosened on the drive shafts.

Hi Wizcrafts, I remember reading a lot of your posts when choosing this machine in the first place, you were very informative. 

Please find attached a photo (hopefully) and see if this would make sense regarding those diagnoses. The area circled in red (I believe is the hook drive shaft) is not turning with the areas circled in green. Thank you very much, Merrick

[friquant]

You may need to engage the safety clutch manually, with a screwdriver. Here is a video that shows how the safety clutch mechanism works, and how to disengage/engage using a screwdriver.

 

[MerrickTNLL]

18 minutes ago, friquant said:

You may need to engage the safety clutch manually, with a screwdriver. Here is a video that shows how the safety clutch mechanism works, and how to disengage/engage using a screwdriver.

 

Spot on, I'll go and try to reset it now. Thank you