Help with tension knobs

[PEU]

I'm new to leather sewing, been practicing for the whole last week and still have some doubts. There are two types of tensioners in my machine, and I guess this is the same for all machines. One squeezes the thread and the other is a wheel with felt on the sides, I mean, this one:

 

I tried one loop, and two loops as seen in the photo, more and less tension, and every now and then, the thread unspools and get stuck on the tensioning spring. 

Here is a YouTube video of the machine slowly stitching: https://www.youtube.com/shorts/4s-va_6a7Ok

Maybe its low quality felt, or maybe is something else you can teach me, because I'm lost on how to prevent this unspooling. If you watch the video you can see that I modified the the thread guide into this knob by separating the incoming thread from the outgoing one (OEM part was a big loop with each one going its way without constraints)

Today I stitched 6 sheaths successfully, but yesterday while practicing, it got stuck twice breaking the thread.

Thanks in advance!!

 

[kgg]

13 minutes ago, PEU said:

Today I stitched 6 sheaths successfully, but yesterday while practicing, it got stuck twice breaking the thread.

To get better help with your problem it would be helpful to know what machine you are using, thread size that you are using for the top and in bobbin, needle size also a couple photo's of the thread path from the spool.

kgg

[PEU]

Machine is Sibyer sb-6180-1 extra heavy duty. Using 270 bonded thread on top/bottom and 794 25/200 diamond needle.

Here is a video I made for a local friend (I speak Spanish in it) it was made before the modification I wrote above, but the path is the same: https://www.youtube.com/watch?v=18aE_q1exxw

Thanks!!

[CowboyBob]

Are you holding onto the needle thread for the first 3 stitches?

[PEU]

4 hours ago, CowboyBob said:

Are you holding onto the needle thread for the first 3 stitches?

Yes I do, practiced this to get the best results and I think I finally nailed on the tension of the first 3 stitches.

Also I don't use the lever to change motion direction, I just turn the sheaths 180 deg, I found this way was better for keeping the stitch tension. Thanks

[Wizcrafts]

54 minutes ago, PEU said:

Also I don't use the lever to change motion direction, I just turn the sheaths 180 deg, I found this way was better for keeping the stitch tension

That's what I do on most of my machines that lack reverse. I call it Poor Man's Reverse.

[PEU]

2 minutes ago, Wizcrafts said:

That's what I do on most of my machines that lack reverse. I call it Poor Man's Reverse.

LOL In my case it does have reverse, but still didn't figured out how to properly do it and not ruin the stitch, will have to practice more, but in the meantime its 180 turns...!

[ljk]

A sewing machine usually has more than one tensioner, the first is called a pretensioner.  The purpose to create enough tension to keep main tensioner thread uniformally seated.

On front mounted machine with a dial or a lever without reverse you can simply go to zero stitch length and make 4 or 5 stitches to lock stitich.  This is the way embroidery machine does jump stitches and they also drag the top thread to the bottom.  I use this method for leatherwork because appearance is important.  My 44 and 31 old black Singer have a stitch length lever but no reverse, so you simply go to zero and make a few stitches.  You can usually pull top thread through to the bottom and trim. On my 280l has a dial and reverse, for stitch quality I go to zero and lock the stitch  This won't work on 111 and clone machines. Also Singer and Adler shoe patchers. It will work on CLSP.

[dikman]

Interesting arrangement of the various tensioners. It looks to me as if tensioners 2 and 3 are in the wrong positions, I would have expected the final tensioner (#3) to have the two tension discs, as it stands now there is nothing to actually grip the thread and stop it coming off the spool if any slack develops as the takeup arm moves up and down.

[kgg]

@PEU I looked at both video's and see you made mods to the last thread tensioner and added a thread guide to the needle bar. Adding the white guide on the needle bar has changed the angle that the thread enters the eye of the needle and by changing the thread guide just above the last tensioner it also changes the thread angle. Did you have this problem before you made changes??

kgg

 

 

Edited March 10 by kgg

[Michiel]

On 3/9/2024 at 2:53 AM, PEU said:

the other is a wheel with felt on the sides

With this type of tensioner, the idea is to make two (or one and a half) turns.
The idea is that the wheel turns with it but experiences resistance from the spring being tightened.
The advantage over the other system is that it is less sensitive to variations in thread thickness.
The pre-tensioner is to keep the wire tight around the disc so that the disc turns with it.
 

[PEU]

18 hours ago, dikman said:

Interesting arrangement of the various tensioners. It looks to me as if tensioners 2 and 3 are in the wrong positions, I would have expected the final tensioner (#3) to have the two tension discs, as it stands now there is nothing to actually grip the thread and stop it coming off the spool if any slack develops as the takeup arm moves up and down.

Thats what I thought when I was trying to solve my tension issues, this week I will put better quality felt and if that doesn't solve the unspooling at that tensioner I will try replacing it with one like you mention

14 hours ago, kgg said:

@PEU I looked at both video's and see you made mods to the last thread tensioner and added a thread guide to the needle bar. Adding the white guide on the needle bar has changed the angle that the thread enters the eye of the needle and by changing the thread guide just above the last tensioner it also changes the thread angle. Did you have this problem before you made changes??

kgg

 

 

I 3d printed this piece when I was trying to solve the problem I described, my rationale was: If I help the thread arrive at the needle in the position it will enter the leather this will be better than it coming from the last thread guide in diagonal.

I think it helped, in any case, it didn't make things worse.

 

8 hours ago, Michiel said:

With this type of tensioner, the idea is to make two (or one and a half) turns.
The idea is that the wheel turns with it but experiences resistance from the spring being tightened.
The advantage over the other system is that it is less sensitive to variations in thread thickness.
The pre-tensioner is to keep the wire tight around the disc so that the disc turns with it.
 

I only use N.10 thread (270/277 per US standards) and don't plan to change in the near future, do you think is a good idea replacing this tensioner?

Thanks to all!

 

PS: some of the sheaths I successfully stitched, photo shows the back side of them.

 

Edited March 10 by PEU

[Quade]

9 hours ago, Michiel said:

With this type of tensioner, the idea is to make two (or one and a half) turns.
The idea is that the wheel turns with it but experiences resistance from the spring being tightened.
The advantage over the other system is that it is less sensitive to variations in thread thickness.
The pre-tensioner is to keep the wire tight around the disc so that the disc turns with it.
 

Does this type work with thinner thread too?  I wondered what the fiber washers were for. I guess they're like brake pads?

For this to work, I'd think tensioner #2 would have to be pretty tight to keep the thread tightly in contact with the tensioner #3? 

Something about this system where the thread isn't squeezed but controlled by the rotation of the tensioner interests me. 

Edited March 10 by Quade

[dikman]

PEU, ignore what I said about the tension assemblies, I got confused (getting old, I guess). I had a look at my 4500 and the assemblies are pretty much like yours in their layout. Varying the number of turns around the last tensioner probably won't help as for some reason you're obviously suddenly getting a lot of slack in the thread between the tensioner and the needle and as the takeup arm comes down that releases the thread around the tensioner, but I can't visualise why this should happen.

Does this happen during a stitch run and nothing changes during that run? Stopping or turning or doing something different? The check spring isn't sticking? I'm not trying to be insulting here, just trying to understand at exactly what point it happens. It's hard trying to diagnose things when you're not there at the time.

 

[PEU]

No offense taken!!! Today I was thinking that maybe a good idea is to setup an old cellphone and record all my stitching until the error happens again, this may take time, but since this is so sporadic I can't imagine other option to spot this problem.

If somebody has ideas on how to improve the thread tension from the 1st post video I'm willing to try them.

[dikman]

Considering it only happens occasionally and your stitching is normally ok that suggests that there's nothing wrong with the way you've threaded it. The only thing I can think of is the check spring sticking in the up position, which would allow slack thread to occur - but I can't see how it would only happen occasionally. 

[Constabulary]

  

On 3/9/2024 at 2:53 AM, PEU said:

Today I stitched 6 sheaths successfully, but yesterday while practicing, it got stuck twice breaking the thread.

 

when heavy thread is breaking it also could be that the hook tip is piercing the thread. A reason can be that the needle bar is set a bit to high (they sometimes raise a bit with the time f.i. when sewing a lot of hard materials or hit a hard spot or the needle plate). When the NB is set to high the hook tip probably pierces the bottom of the thread loop. So I would check the needle hook timing and even when you think it is set right try to lower the NB a tiny bit. Just a suggestion - maybe it helps, maybe not.

I cannot see when the thread is unspooling in the video. But I would control the travel of the check spring. The travel of the check spring should stop when the needle tip is above the needle plate or above the surface of the material. I guess the the tension unit has a rest for the check spring that can be adjusted.

Edited March 11 by Constabulary