Juki DU-1181N - Looping/losing tension on seams

[toad92]

Not strictly an issue pertaining to leather, but I figured this would be the best place to ask.

I just finished setting up my DU-1181N last night and ran a few stress tests to calibrate the tension, foot pressure, etc. I intend(ed) the use the machine primarily for topstitching on woven fabrics, mostly with Tex 100 polyester thread.

I realize now that a top and bottom feed machine is probably not an ideal solution for topstitching items with frequent changes in layers like folds and seams, particularly seams on hems. With the stock configuration the machine was having great difficulty mounting and dismounting large seams/folds, so I adjusted the middle foot height and it managed to (mostly) remedy the issue.

However, despite playing with the tension for almost an hour I can't seem to prevent the machine from creating loops under the fabric (losing tension? Needle deflection?) on the more substantial differences in layers. This persists even with a shim/hump jumper to keep the foot level.

I've had the same issue with my Juki DDL drop feed machine, which only seemed to be mitigated by cranking my bobbin tension (and thus enabling me to crank the upper tension), reducing my stitch length and switching from a TEX 75-80 thread to a TEX 60. Thus I sought to acquire a machine that could accommodate a larger needle so I could use a thicker thread for more pronounced topstitching.

Acknowledging I probably should have gone with another drop feed machine like the DDL-8700H (or possibly a DLN?), is there anything that I can adjust to mitigate this looping?

Edited June 27 by toad92

[friquant]

Lift
Which piece did you adjust to achieve greater center toe lift? I typically raise the lift of both pressers together, meaning if I have lots of humps to jump I put the lift at its max (with equal lift per presser).

Tension
In my experience, thicker fabric requires more top tension. So to have no loops, you would need enough tension to match the thickest section of your seam. It's odd that yours is mostly looping only on the transition from thin to thick.

If I'm counting your folds correctly, your thickest section is nine layers of denim. I would set up a test piece so you can do an entire seam through nine layers, and use that test piece to sort out needle size and top tension. Give just enough tension to hide the bottom knots on the thick test piece, then go back and see how those same settings do on your standard piece with the thick / thin transitions.
 

Edited June 27 by friquant
Suggestion for test seam

[Wizcrafts]

I sometimes sew denim with walking foot machines. I only tweak the check spring position and balance the tensions so the knots don't show on the outside. I find that as long as there is sufficient pressure on both feet to hold the material all the way down against the feed dog, I don't get odd knots or skipped sititches. So, try adding more foot pressure. Adjust the inside foot to press down just before the needle hits the material. Match the check spring throw to stop just as the needle penetrates the material, and not before.

[toad92]

On 6/27/2025 at 12:29 PM, friquant said:

Lift
Which piece did you adjust to achieve greater center toe lift? I typically raise the lift of both pressers together, meaning if I have lots of humps to jump I put the lift at its max (with equal lift per presser).

Tension
In my experience, thicker fabric requires more top tension. So to have no loops, you would need enough tension to match the thickest section of your seam. It's odd that yours is mostly looping only on the transition from thin to thick.

If I'm counting your folds correctly, your thickest section is nine layers of denim. I would set up a test piece so you can do an entire seam through nine layers, and use that test piece to sort out needle size and top tension. Give just enough tension to hide the bottom knots on the thick test piece, then go back and see how those same settings do on your standard piece with the thick / thin transitions.
 

See picture. I can probably raise it another 1/4" - 3/8". Where would I adjust the outer foot height?

Yep, the looping mostly occurs while the feet are mounting and dismounting the hump. I also get looping when I edge stitch around the corner of a facing on my DDL (haven't tried yet with my 1181N) unless I temporarily decrease the stitch length.

Thanks for the suggestion; I'll give it a try and report back.

On 6/27/2025 at 12:30 PM, Wizcrafts said:

I sometimes sew denim with walking foot machines. I only tweak the check spring position and balance the tensions so the knots don't show on the outside. I find that as long as there is sufficient pressure on both feet to hold the material all the way down against the feed dog, I don't get odd knots or skipped sititches. So, try adding more foot pressure. Adjust the inside foot to press down just before the needle hits the material. Match the check spring throw to stop just as the needle penetrates the material, and not before.

Anecdotally I've tried adjusting the check spring position on my DDL machine but it didn't seem to make a difference.

How would I adjust the timing of the inside foot?

[friquant]

33 minutes ago, toad92 said:

See picture. I can probably raise it another 1/4" - 3/8". Where would I adjust the outer foot height?

 

I'm attaching a photo of my machine that has adjustment screws "A" and "B" labeled.
"A" adjusts the amount of overall lift (to be shared between the two pressers).
"B" adjusts the needle-to-inner-toe timing, and at the same time is what you adjust to achieve equal (or unequal) lifting heights between the two pressers.

I'm assuming you loosened "A", raised the arm in the slot, then tightened back up. This is what you would do to be able to walk over bigger humps. (Sometimes I need this set to max to be able step down off of a hump too, or else the back of the outer toe hangs up.)

To see how to adjust "B" for equal walking heights, see Uwe's video. In his video he sets it for equal lift height. If you set the lift height slightly UNequal, your needle will land just before or just after the inner toe. You can experiment.

 

 

Edited June 28 by friquant

[friquant]

By the way, I went looking for a manual for this machine, and I found this one which unfortunately is in several languages: https://www.juki.co.jp/industrial_j/download_j/manual_j/du1181n/menu/pdf/instruction_7K.pdf#page=1

Page 36 begins the section on ratio of movement between the two walking feet