Tension question - Class 26

[Landcruzer94]

I have an issue with setting the tension on my Class 26.  Here is what I'm working with

Fresh size 20 LR needle

92 thread

2 pieces of 3-4oz leather

Threaded and bobbin loaded according to LM Co's instructions.

 

When I'm sewing I have the tension adjusted to bury the knot equally between both pieces of leather, but every time I stop and turn a corner (1/4" above BDC) the top thread pulls the bottom up and leaves the knot exposed. Doesn't matter if I use the foot pedal to raise the foot or just turn the piece under pressure the same thing happens.  If I lower top tension to help the corners then all the knots start showing on the bottom.  There doesn't seem to be a middle ground that will solve everything.  I'm only adjusting the main tension knot, everything else is factory from Leather Machine Co.  Sewing size 69 thread didn't seem to be an issue with a size 18 needle.

 

I also note that the tension mechanism seems to be making some extra clang noises that I don't hear on others machines on YouTube.  

The final cycle is done by hand to show the kind of tension that's on the top.  It doesn't feel right to me so maybe others can confirm.

[JREESER1]

Make sure the needle is starting the up-stroke, before you make the turn. (even just barely starting up)

[Landcruzer94]

1 minute ago, JREESER1 said:

Make sure the needle is starting the up-stroke, before you make the turn. (even just barely starting up)

Yes it's 1/4" or so above bottom dead center before I do

[Constabulary]

when I make turns my needle tip is still in the material the way that I see needle scarf - maybe worth giving it a try.

BTW - have you opened your slide plate / hook cover and watched the thread when it slides around the hook? Maybe it keeps hanging somewhere maybe on the bobbin case opener or the hook needs some adjustment - just a guess.

Edited August 30, 2024 by Constabulary

[kgg]

11 hours ago, Landcruzer94 said:

I also note that the tension mechanism seems to be making some extra clang noises that I don't hear on others machines on YouTube.  

Maybe you might want to send Leather Machine Co. an email with the video to determine what the clanging noise is.

kgg

[TomE]

To narrow the possibilities, I would test with thin veg tan leather and a TRI point needle.  I am interested in learning more about this symptom.  I  mainly sew heavier leather with #138 thread on a Class 26.

[Landcruzer94]

Thank you all for the suggestions.  I tried the suggestion by TomE, switched to veg and a diamond point needle and unfortunately did not remedy the issue.  I did however uncover the source of the sound I referenced earlier.  The slapping sound is because of the top thread binding within the shuttle(?) below as the string goes around.  The below video shows the two slapping sounds, first as the thread goes over the first gap, second as it binds down below and finally the takeup spring slaps upward as it breaks free.  This does not sound/look normal to me and may be the source of at least some of the tension issues that I have.

 

 

9 hours ago, Constabulary said:

when I make turns my needle tip is still in the material the way that I see needle scarf - maybe worth giving it a try.

BTW - have you opened your slide plate / hook cover and watched the thread when it slides around the hook? Maybe it keeps hanging somewhere maybe on the bobbin case opener or the hook needs some adjustment - just a guess.

You may be on to something, per the video I just posted.

[Constabulary]

I have not worked on machines with this type of hook for a loooong time. I guess its a thread take up lever or hook timing issue (or both).

 

[Wizcrafts]

First of all, I see thread that is bound onto the bobbin hold down tab. Free that thread before you do anything else! There should never be thread trapped like that!

After freeing the thread from the tab, check the hook timing vs the eye of the needle on the upstroke. A properly timed hook will intersect the needle about 1/8 inch above the eye and sill be within the scarf cutout. Many times, a late hook will cause that snapping sound. Advance the hook a bit the loosen the thread loop.

The check spring comes into play here. If the travel is too long, the top thread stays taut longer than necessary. Before you change the bottom stopper, try moving the screw in the curved slot to the right end of its travel. If that doesn't help, loosen the screw under the bottom stopper bracket and move it so the spring only moves a little past when the needle makes contact with the top of the leather. This adds slack thread and reduces the tension as the thread goes around the bobbin case.

[Constabulary]

Wiz, I think the bobbin thread belongs there. Thats what the gap in the bobbin retainer is for. Other machines have it this way or very similar too