Suggestion on bottom stitch issues on my new Juki DNU1451S

[LunarConcepts]

Hello, I recently purchase a Juki DNU1541S and I am having an issue with my bottom stitch making a loop whenever I make a turn (generally a 90*). I am sewing a heavy nylon webbing. I have been through increasing and decreasing both top and bottom stitch tension to the extreme. I have to run a decent amount of top stitch tension as this stiff is rigid and has a very tight weave. When I have the top stitch tension tight, it pulls the bottom stitch loop up through the material excessively to the point that my 90* corners are not crisp but rounded off. I can work with the top and bottom stitch tensions till it no longer pulls the bottom stitch through the material but then the loops start forming on the bottom side.

This is normally only an issue for the first stitch after turning the material. All this is better shown in the picture. This is an issue I don't have on a Brother LS2- B837 and I am not sure if it has something to do with horizontal vs. vertical axis machine. Its almost like I am getting an excessive amount of slack when knee lifting the presser foot when turning. I did try actually just spinning the material under the foot without lifting and it made no notice improvement and in one instance made it worse

I appreciate any suggestions. Thanks for a great forum.

 

 

[Tejas]

The problem might be lifting the foot too high, opening the tension disks. You might try lifting the foot only high enough to turn the material. The needle should be buried and just on its way up.

[Russ]

I agree with Tejas.  I have a 1541S and a couple of other machines, and the Juki is unique in that it wants the needle almost all the way down when making a 90 degree turn.  My other machines like the needle much higher.

 

[Gregg From Keystone Sewing]

I'll look into it as well, I'll try what Russ said.  This is not the 1st time I've seen this issue before.  

[LunarConcepts]

Thank you all,

I will try turning the material prior to going past needle bottom. I always went past bottom on the Brother to make sure I didn't deflect the needle away from the hook and miss catching the corner stitch. This seems to be more of an issue when I am only sewing through a single layer. It is very frustrating as its usually right a the end of the project. It certainly kills the feeling of a successful finish.

I have tried not raising or barely raising the presser to make sure it wasn't releasing the thread tension at all but really there is no load on the thread so I am not sure how it would?

Gregg, Loving the new machine. All is well, I just need to get this last little thing figured out. The repair on the Brother has made it better than ever.

Thanks for any additional input!

 

 

[Gregg From Keystone Sewing]

On 11/26/2016 at 2:20 PM, LunarConcepts said:

Thank you all,

I will try turning the material prior to going past needle bottom. I always went past bottom on the Brother to make sure I didn't deflect the needle away from the hook and miss catching the corner stitch. This seems to be more of an issue when I am only sewing through a single layer. It is very frustrating as its usually right a the end of the project. It certainly kills the feeling of a successful finish.

I have tried not raising or barely raising the presser to make sure it wasn't releasing the thread tension at all but really there is no load on the thread so I am not sure how it would?

Gregg, Loving the new machine. All is well, I just need to get this last little thing figured out. The repair on the Brother has made it better than ever.

Thanks for any additional input!

 

 

Glad to hear it, thanks so much.  Keep on me with the DNU-1541S and turning the work while in seam, I want to get to the bottom of this.  Again, not the 1st time I've had this brought to my attention.

[TinkerTailor]

Just drawing at straws here but this came to mind:

Have you tried with a needle a size up or down? I know webbing can tighten down on the needle and the hole closes back up. I wonder if the act of turning the work causes the thread to wrap around the needle a little and get slightly tighter, or perhaps stopping the needle motion to turn allows the webbing to collapse the hole, effecting the ability of the machine to pull the top tight at the end of the stitch cycle? Also, just curious, what happens if you turn a 90 the other way? I wonder if it makes a difference whether you turn towards or away from the hook. If it is the same both ways i would lean to a needle/thread/lube issue but if it changes with direction i would suspect something going on in the hook with loop formation. Again, just a shot in the dark.
Thread lube may help as well.

 

[LunarConcepts]

On 11/28/2016 at 0:55 PM, TinkerTailor said:

Just drawing at straws here but this came to mind:

Have you tried with a needle a size up or down? I know webbing can tighten down on the needle and the hole closes back up. I wonder if the act of turning the work causes the thread to wrap around the needle a little and get slightly tighter, or perhaps stopping the needle motion to turn allows the webbing to collapse the hole, effecting the ability of the machine to pull the top tight at the end of the stitch cycle? Also, just curious, what happens if you turn a 90 the other way? I wonder if it makes a difference whether you turn towards or away from the hook. If it is the same both ways i would lean to a needle/thread/lube issue but if it changes with direction i would suspect something going on in the hook with loop formation. Again, just a shot in the dark.
Thread lube may help as well.

 

Thanks for commenting! I have this almost entirely eliminated primarily through increasing the bobbin tension to what I would feel would be way to much but if it works....

Basically I got pissed off at the Juki and went back to my old Brother. I managed a relaxing 2 hours of making belts and when my head was in a good place I sat back down with the Juki and backed everything out and started working my way in. I would roll over to the Brother and give the top thread a pull and then back to the Juki to adjust the tension till my calibrated elbow felt they were the same for both machines. I did the same for the the bottom stitch and realized how much less the Juki was even after yo-yoing the bobbin case to get it into the normal tension range. I went for broke on the bottom tension and dialed it tighter with positive results and without an impact on the top stitch.

I am going to give a thread luber a shot. This webbing sews up rock hard and the smoke rolls off the titanium coated needles. I would love to eek out a bit more top stitch tension which I am hoping will snug up the last little bit of slack on my corners

Thanks again!

[Tejas]

Here are links to how to measure, and reliably set, tension with a spring gauge.

http://sew24.blogspot.com/2012/11/how-to-measure-thread-tension-with.html

http://jukiindia.com/Item-List/Adjustment_Procedue.pdf

[brmax]

+1 on the links,  I like Juki's method of measuring the bobbin. I thought I was abstract in a similar method, not so much now  (snap finger) darn it

Being interested in all the in's and outs or why,s to my understanding the machine, other than me hittin the go pedal. Here's what I tried in my first machine and subsequent 1541 and one can use it handily with other machines. Though tensions change it was a good mark or judge point for myself on a consistent material; I sewed a very small bag "almost closed" cut the top thread leaving bobbin thread attached and insert weight or weights in sewn bag, let it position over the operator side edge and adjust weight to slowly drop down.

I measured this in different ways and was 27grams, or 417grain for my particular job and machine, remembering what someone mentioned it can change with material n threads. So for this I adjusted a couple and put in a Ziploc, and can be a handy idea.

With that mention behind, I have been curious of the winding effect on thread at the needle as re positioning materials, and at points thought this is tougher than normal. It may be possible to be losing a stitch.  In some ways if we look at videos of thread at certain points through the sew cycle when the needle returns to go up its in free state or thread is sliding through eyelet.

As mentioned this can be a top drawer adjustment with needle selection for a specific action when known, no doubt worth further discussion. So in short a small eyelet could have enough tension in thread to pull up some and or in a repositioning remove the normal amounted loop of thread usually waiting on the hook.  That was deep, so coming up for air!

out for coffee

Floyd