Juki 158 Double needle thread

[biggdave92]

We sew 400d nylon primarily.  Outside thread keep untwisting.  Using tex 135 left twist.  Any tips on how to solve this issue? thanks!

[Northmount]

Use right twist for the outside thread.  I recall reading a couple threads on this subject if you want to search for more information.

Tom

[Gregg From Keystone Sewing]

ROT (Right Outside Twist, also called an S twisted thread) would help, but also make sure you are using bonded thread, that remains one cord if you twist in between your fingers a few times.

 

[gottaknow]

I set all my double needles the same.  I retard the timing on the left hook a little as bonded thread, (and most others) form the largest loops just above the eye on needle bar rise. You also want a very sharp hook on the left side so it can be set as tight as possible. Lots of folks ruin their hooks when they break thread and promptly sand their hooks dull. Dull hooks break thread. 

The newest Juki double needles (I have the 3578-A's) the timing marks are now placed so the hook comes in right above the eye. A significant change over earlier machines. They seldom break thread. 

Regaeds, Eric 

[Dave9111]

Sorry to resurrect a sleeping message thread but I have the same issue, I think.

I just bought what appears to be a Consew 339RB clone.   Its a double needle machine.

The guy I bought it from complained that it had issues and he mentioned issues with the left needle shredding the thread.   I re-timed the right hook and that solved most of the issues.   

However, the outside/left top thread keeps untwisting and after several feet of stitching, the top left thread is not a thread but a number of loose filaments!

The left hook is apparently unwinding the left/outside top thread. 

I ran into this message thread looking for a solution. 

I tried both V92 and V138 thread and some different versions of bonded poly and the left hook is very effective at unwinding the left top thread no matter what. 

"Bonded" Poly is not THAT bonded! 

However, after looking at another Youtube video of a very similar machine, I realized that there is supposed to be a wad of cotton, foam, or felt that holds the threads leading to the needles up against the machine. 

My machine has the chrome "wad of felt/cotton holder" but the wad is missing. 

Could the purpose of that wad of cotton also be to keep the thread from unwinding back to the tension mechanism?    Look here at 2:25 and you can see the chrome cotton holder and the cotton pressing the thread against the machine.

I did find some right twist thread online and I have a pound of White V138 coming but this right twist thread is pretty rare. 

Trivantage has some, but I'm not a customer, but even then they only have it in black and white.

So is this a burden that users of double needle machines must deal with?    I thought I would just lube it, load it up with thread, correct the timing and it would work fine with "standard" left hand twist thread.

Not so.

Thanks,  Dave

 

Edited September 15, 2021 by Dave9111

[Constabulary]

7 hours ago, Dave9111 said:

Could the purpose of that wad of cotton also be to keep the thread from unwinding back to the tension mechanism?    Look here at 2:25 and you can see the chrome cotton holder and the cotton pressing the thread against the machine.

that's a thread oiler / lubricator with a felt pad.

10759A ARM THREAD GUIDE D LOWER SEIKO JW28BL

10760 THREAD GUIDE FELT SEIKO LSW

I have a double needle machine too and I´m using left twist in both hooks - no issues yet. I´m using #30 Gütermann TERA Polyester thread (not bonded)

https://industry.guetermann.com/en/products/product-finder/tera-30-wa

BTW - the guy in the Video hast the right angle thread guide on the tension unit installed incorrectly and therefore he is threading not the way it should be threaded. However - if it works it works.

Regarding bonded or not - you have to ask your self if a bonding is REALLY required on your product - or not. I never use boded thread.

Edited September 15, 2021 by Constabulary

[Dave9111]

Thanks for the reply!

So that's a thread oiler/guide.   That makes sense.   Thanks for the parts reference.

I went and looked at the machine again and both of the hooks rotate clockwise.   But only the left thread has this issue.

Do both of your machines hooks rotate clockwise as well?

I have always used bonded polyester thread as it is the most common thread in the US for sewing Polyester Canvas and boat sails.

But like I mentioned, the thread is easily untwisted.   So its not very "bonded".

I didn't notice the error in his tensioning setup. 

Does your machine also have the small pins next the friction disks in the tension mechanism? 

Do you wrap the thread around those pins as he mentions in the video?

I was doing that and I was getting inconsistent tension, so I rerouted the threads to not use the small pins and tension control seems to be improved.

I thought that perhaps pulling the thread around the pin might be unraveling the thread, but that was not the case.

Here is a picture of my left thread after sewing a few feet of stitches.   Its unraveled all the way up to the takeup.

I wonder if the thread you use is more tightly wound than the thread I am using.   Perhaps it is untwisting, but not enough to show the  individual strands?

Thanks,  Dave

 

 

[Wizcrafts]

As an experiment, try using only the left needle and feed the right thread to its guide hole. If it still unravels, the hook and needle position/timing is the problem. If not, something in the thread path is the problem. Or, there could be an unseen burr on the thread guide hole in the needle bar.

Have you removed the sliding cover on the left and watched the hook action at pickoff time? That could reveal the cause.. The hook may be damaged, or not properly distanced, or timed. Did you read the early replies in the original topic?

[Michiel]

When i thread a machine i usualy take one or two turns trough / around the thread pin on top of the machine

most of the times i do not see much difference in the way i make the turns.

but with some thread, when it starts to un-twist in the needle it helps to make turns the right way

(in one direction it will make the thread  loser and in the other way more thight)  this works for me….

[Michiel]

I mean the trhread guide pin:

 

Edited September 15, 2021 by Michiel

[Dave9111]

>>As an experiment, try using only the left needle and feed the right thread to its guide hole.

I did that and I isolated the problem to the left hook which simply untwists the thread.   I also checked for burrs everywhere. 

However per Constabulary's mention of the thread lubricator, I found a piece of foam, cut it and and pushed it into the holder and lubed it with sewing machine oil and put the threads behind the foam.

I also re-threaded the machine per the video, which is how it was threaded when I got the machine.    I had cleaned the tension mechanism when I took it all apart looking for burrs.   Nothing was found but there was a lot of dirt/gunk in the disks.  

Now the tension system seems to be much smoother than when I first got the machine.    The gunk must have been affecting the tension mechanism. 

Now everything is different.   The left hook is still untwisting the thread.   Yet the machine runs ok now, even at high speed, and the stitches look good.    So I think the only way to get rid of the untwisting is to use the right hand twist thread as was mentioned at the beginning of this message thread.   However it is really nice that I can now run regular left hand twist thread and the machine will function!  :-)   The fact that the thread is untwisted somewhat is not great, but its not very noticeable in the finished stitches.   Still, I think having a right hand twist thread in the left needle would be better.   I have a pound of V138 right hand twist, on its way. 

With the thread lubricator/guide in place, the thread is apparently under better control between the takeup arm and the thread guides at the needle bar.

I wonder how long my "foam" lubricator block will last.  I used a small piece of foam carpet padding as the donor material for the lubricator block.   I think it is polyurethane foam.

I added a pict of the current machine threading  and the results of my latest test run.   The unraveling of the left thread is not obvious in the picture since the takeup arm is up all the ways so the threads are under some tension. 

The test run is about 24 feet of stitching.  About half of it at full speed, which I think is about 2300 spm.   There are some double stitches in there as I was testing the reverse as well.   

Anyway, I am going to consider this problem solved for now.   I'll let you know how the right hand twist thread does when I get it. 

I think the key fix was the lubricator/thread guide, which keeps the threads under better control. 

I'm always amazed at how much a little, seeming insignificant change like this can really make a huge difference on a sewing machine.

Thanks for the help everyone!  

 

Edited September 15, 2021 by Dave9111

[Wizcrafts]

@Dave9111 - You can counteract a particular twist in a spool of thread by wrapping in the opposite direction around a thread post or guide that has 2 or more holes. I do this with twisty thread by feeding it counterclockwise through two holes in a post. You might try that, or go clockwise to see if one or the other improves the thread holding its shape.

[Dave9111]

Thread post.   Interesting idea.   There aren't traditional thread posts on this machine.   They are identical to the ones in video.   The post is horizontal and has one hole in the side of it, then the post becomes tubular and the thread goes through the tube.

Pretty odd.    None of my other machines have that type of post/guide. 

I have one wrap around the post before the thread goes into the tube..

Now I wonder would would happen if I put several wraps around the post?? 

Hmmmmm.......

[Wizcrafts]

If your machine has a spare hole on top you might could buy a post with a few holes and pound it in a bit. Ideally, there should be about an inch between the top and bottom and even better, they would be 90 degrees apart. I have that kind of top post on a few of my machines and they are perfect for counteracting twisty thread, or adding extra tension on top without cranking down the beehive spring, which tends to limit the separation when the feet are lifted.

[Dave9111]

On 9/15/2021 at 9:02 PM, Wizcrafts said:

If your machine has a spare hole on top you might could buy a post with a few holes and pound it in a bit. Ideally, there should be about an inch between the top and bottom and even better, they would be 90 degrees apart. I have that kind of top post on a few of my machines and they are perfect for counteracting twisty thread, or adding extra tension on top without cranking down the beehive spring, which tends to limit the separation when the feet are lifted.

Thanks Wizcrafts.   I'll look into that.    I'll also let you know if the right hand twist thread fixes this issue or not. 

The thread post that Michiel showed might help. 

Edited September 17, 2021 by Dave9111

[Dave9111]

The right hand twist thread arrived yesterday.  

Its a V138 bonded polyester that looks nearly identical to the Dabond polyester that I have been using.

I did nothing to the machine other than remove the existing left needle thread that was a left twist thread (Z twist - standard thread) and I replaced it with the right twist (S Twist) thread.

Wow, what a difference!  

No unraveling at all.  The stitches on the right and left side now look the same.   The left top thread looked a little odd before.  Not a huge issue, but they did look different. 

If you have a dual needle machine and the left needle thread is unraveling, get some right twist thread.   I bought the thread from "The Thread Exchange" in North Carolina.   I think it was $29 plus $10 shipping for a pound.

Trivantage has right twist thread as well, but I don't have an account with them yet. 

Trivantage also has right twist thread in PTFE in V90 and V138.  

Here are the threads slack in the machine after sewing about 15 feet of stitches.   Notice that both thread are wound tight, no unraveling.   Compare this to the picture above with the left hand twist thread in the left needle.