Singer double needle thread snagging and skipped stitch on one side

[nylonRigging]

I always sewing in late evenings, and just finished couple items on double-needle machine . Here Pic. of using good quality nylon T-70 on the Left-Needle after a couple items finished stitching . L-needle thread always gets compromised. You can see it when stopping on the needles up-stroke, and you can see the way L-side will eventually loosens the twist even with using Good quality Bonded. 
On the down-stroke thread tension and twist is pulled tight, and the finished stitching on the product looks good. You can't see the compromising on the thread twist even using magnifying glass, but you got to always keep eye on it, and when see it getting loose twist just peal-off a few feet of thread on that L-needle to freshen it up before starting on new item.

You said you using #20 needle and T-80, and that probably good to go. but like @nejcek74  said you might try bigger like #22 if ? you got thick over lapping with material, and larger might keep the fiction temp lower pulling threw the needle . 
I usually go with a #18 with the 69/T-70 thread. It what I usually stick with. In the Pic. the items sewn was multi-layer '5 layers' nylon, and It takes a couple items finished moving pretty steady to start looking like this. So that a lot of friction/needle heat till I freshen-up the L-side thread. 
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Edited yesterday at 09:22 AM by nylonRigging

[AlZilla]

As usual, I'm not the expert on these things, but I've always understood that on a true twin needle machine, the left needle needs right hand twist thread.  (Not necessarily correct - see below)

The reason they get away with it on domestics with the double needle attachment is that it uses the same bobbin for both threads.

I'd bet if you dig back thru old Singer manuals, there will be a reference.

EDIT: I don't know where I got the idea of right twist thread for the left needle. I've looked through a couple of pdf manuals I have and they both say left hand twist in both needles.

[DMH]

@councilman24@nylonRigging thanks for the advice on the thread quality.  The right needle is using tex 80 cotton polyester core thread from Wawak.  The left was cheaper brand thread from Kava.  I agree the cotton/poly thread is better quality and I didn't take that into consideration.  The cost of good thread is out of control and the cheaper options are just not worth it.

There is definitely a difference between a $9 roll of thread and a $28 roll of thread.

If I'm ever going to be a small batch denim workshop I have to keep all of this in mind.  This is a lesson learned.

Edited yesterday at 01:33 PM by DMH

[DMH]

@nejcek74 @nylonRigging I will consider a #22 needle.  I recently changed to #20 in anticipation of using tex80 thread.  I have another topic on leatherworker.net with all the issues I had retiming the machine to work with the bigger size needle.  I will look at the spacing between needle and hook on both to make sure they are consistent.

 

All of these little trials will make me better at this.  I would rather learn to do it myself than rely on a overpriced mechanic to do it for me.

Edited yesterday at 01:29 PM by DMH

[DMH]

2 hours ago, AlZilla said:

As usual, I'm not the expert on these things, but I've always understood that on a true twin needle machine, the left needle needs right hand twist thread. 

The reason they get away with it on domestics with the double needle attachment is that it uses the same bobbin for both threads.

I'd bet if you dig back thru old Singer manuals, there will be a reference.

@AlZilla you're correct the manual does mention the right hand twist thread.  I read it and didn't know much about it and I have to admit I disregarded the importance of it, but I'm learning that lesson now the hard way.

[friquant]

I don't have a double needle machine (yet!) but what an interesting challenge. 🤔

 

1 hour ago, DMH said:

 

This excerpt (from the 112W139 manual, I presume) actually says to use left twist thread for both needles. 

 

18 hours ago, DMH said:

I need help figuring out why the thread keeps snagging and stitches are skipping on one of my needles.  Both sides have the same weight thread and needle size, but the left keeps balling up the thread and skipping stitches.  I've adjusted the tension multiple times, but it's not getting better.  

 

 

 

@DMH This photo you posted shows both left and right threads having about the same twist when they land in the fabric. It's also skipping several of the first ten stitches in the seam (no time for thread unwind to happen). What I'm saying is the left side may be skipping due to other issues.

 

5 hours ago, nylonRigging said:

You can see it when stopping on the needles up-stroke, and you can see the way L-side will eventually loosens the twist even with using Good quality Bonded.


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@nylonRigging What machine are you using? I was hoping someone would show a photo like this...at the end of a seam so we could see the two sides.

[nylonRigging]

5 hours ago, friquant said:

 What machine are you using? I was hoping someone would show a photo like this...at the end of a seam so we could see the two sides.

This one is the Juki ( mdl. LH-3528A ) I bought new about 12 years back, It gets run pretty regular and I have Zero negatives about this juki mdl. and would not hesitate to buy another one . it basically is just a more modern design variation of the oldschool workhorse Singer double-needle/needle-feeds . But I still keep the old singers around . I even have a real old 211 that I have replaced both L&R-sides with complete bobbin assemblies back in 2015 and it still going strong to this day. It is just a proven design that gets used worldwide for many decades.

I really just never think about the L-side needle problem anymore. I used to worry about it years ago for someway to fix or conquer the dreaded L-needle/thread twist on the double-needles . But reality is it just a minute problem, you just buy good thread, periodically throughout the day check it sewing, and get your work done.... LOL

.

[nylonRigging]

9 hours ago, AlZilla said:

As usual, I'm not the expert on these things, but I've always understood that on a true twin needle machine, the left needle needs right hand twist thread. 

The reason they get away with it on domestics with the double needle attachment is that it uses the same bobbin for both threads.

I'd bet if you dig back thru old Singer manuals, there will be a reference.

Along with single-needle and double-needle lock-stitch . You see a LOT of Industrial double-needle 'Chain Stitch' on the denim Jean industry being used.

Denim Jean Seam

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[DMH]

I think the issue was the thread I was using on the left needle.  I changed it to another tex 80 cotton poly fill and had no issues.  To make sure I switched back to the all poly and the thread immediately started again.  To make sure I switched back to the cotton/poly gave it a few passes and even a heavier denim with multiple layers and no issues at all.

I have 4 rolls of this tex 80 poly in 2 colors, but hopefully it won't go to waste.  When I get started on my waistband setup on my double needle Union Special, I'll start with #21 size needles and hopefully I will get some use out of this poly thread.

No more rolls of thread from Canada regardless of the low price.

[DMH]

31 minutes ago, nylonRigging said:

Along with single-needle and double-needle lock-stitch . You see a LOT of Industrial double-needle 'Chain Stitch' on the denim Jean industry being used.

Denim Jean Seam

@nylonRigging the US I'm going to be working on is chainstitch, my first, it should be another learning experience.

 

I like that video you sent.  A feed of the arm chainstitch machine is on my wishlist.  Even a used Juki is close to 2K and a vintage Union Special is over 3K, but I will definitely be adding one to my workshop.  Along with a old school keyhole style buttonhole machine.  Lots of old machines to choose from in CA, but the shipping alone to FL can get pricey.