Juki 1246-6 Skipping/Breaking Thread - Help!

[brad Harper]

Hello Forum

I'm hoping that one or a few of you will have some suggestions for me.

I have a Juki 1246–6 - wheel feed - single needle - post-bed machine(see photo). I build custom bike shoes and have been using this particular machine for almost 20 years. Recently I have begun to sew thinner leather type materials. I have noticed when sewing thinner materials that my machine will occasionally skip or break stitches. Sometimes just a little and sometimes I can barely get through the project. I use Nylon Size 69/Tex-70 thread and It seems to matter which brand thread I'm using. I assume the amount of thread bonding or something affects it?  When sewing thicker materials it sews like a dream.

Do any of you have a suggestion as to why this would be happening? or suggestions of machine settings that will help with this?

Any help or ideas is greatly appreciated

 

Brad Harper - Harper Sports Inc. - www.riivo.com

Edited October 23, 2023 by brad Harper
forgot something

[shoepatcher]

Check hook for burrs.   Make sure the the pressure on the thinner materials is a little more.  Keeps leather from coming up.  Also check that hook is as close as you can get it to the needle without touching it! Check timing as well.

glenn

[Wizcrafts]

Maybe tweak the check spring to get a larger loop formed as the needle begins its ascent. There will be 3 adjustments possible: strength, travel and starting position. Try minimizing the travel so the spring stops as soon as the needle penetrates the top of the material. Back off the tension on the spring a bit. Try adjusting for more or less slack in the thread. Sometimes, adding slack helps overcome floppy material dissolving the loop. Othertimes, reducing the slack may do the trick..

[brad Harper]

12 hours ago, Wizcrafts said:

Maybe tweak the check spring to get a larger loop formed as the needle begins its ascent. There will be 3 adjustments possible: strength, travel and starting position. Try minimizing the travel so the spring stops as soon as the needle penetrates the top of the material. Back off the tension on the spring a bit. Try adjusting for more or less slack in the thread. Sometimes, adding slack helps overcome floppy material dissolving the loop. Othertimes, reducing the slack may do the trick..

Wizcrafts I think you may be onto something with this. I have always assumed it has something to do with the loop of thread that the hook has to catch. I will definitely try what your suggesting. To be honest I have never fully understood what the "take up spring" is for on the machine. "Take up spring" is what Juki calls it in the instruction manual. I think I am following what you are saying. 

Edited October 24, 2023 by brad Harper

[ljk]

One more thing you may have what I call vertical axis thread break phenomenon.  That is when thread particles get built up under the hook.  Last resort.  Do  use posted advice first.

[brad Harper]

On 10/23/2023 at 8:04 PM, Wizcrafts said:

Maybe tweak the check spring to get a larger loop formed as the needle begins its ascent. There will be 3 adjustments possible: strength, travel and starting position. Try minimizing the travel so the spring stops as soon as the needle penetrates the top of the material. Back off the tension on the spring a bit. Try adjusting for more or less slack in the thread. Sometimes, adding slack helps overcome floppy material dissolving the loop. Othertimes, reducing the slack may do the trick..

Wizcrafts you were dead on. The main culprit was the spring starting point. It was way too low. The spring had too much downward travel. I adjusted it like you suggested to stop right when the needle enters the material. I have been sewing with it this way for 2 days and have not skipped a single stitch! Works perfectly in either thick or thin material. Big Thank You!

[Wizcrafts]

12 hours ago, brad Harper said:

Wizcrafts you were dead on. The main culprit was the spring starting point. It was way too low. The spring had too much downward travel. I adjusted it like you suggested to stop right when the needle enters the material. I have been sewing with it this way for 2 days and have not skipped a single stitch! Works perfectly in either thick or thin material. Big Thank You!

Yea! Another win for the good guys! Glad it worked for you.