Help with tension knobs

[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, 2024 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, 2024 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, 2024 by Constabulary