Poly vs. Nylon ? Same size, different adjustments

[Wyowally]

Normally if you use 138 nylon or are set up for 138 polyester and use quality thread and want to switch, do adjustments just need to be tweaked a little?  Is a needle change ever necessary? I think I have found differences in the same brand of polyester thread, same size, different color that made me change bobbin tension. Just hoping that setup doesn't have to start from scratch when switching nylon vs. polyester.

[Wizcrafts]

Bonded nylon is almost always stiffer than bonded polyester thread. Black bonded thread is most always stiffer than other lighter colors. I asked a thread company about this and was told that they first dyed the raw thread dark blue, then black. This is why it was stiffer. That was in the late 1980s.

I used to use bonded nylon thread from Weaver. Some of the black spools had the thread coming off like a coil spring! I had to thread it counterclockwise through the top guide posts on machine I ran it through to counteract the twist. While still twisty, their white, chestnut and straw thread wasn't as hard to keep straight.

So, to answer your question, yes, you may have to change either the top or bottom thread tensions when switching from nylon to polyester thread, or possibly, from light colors to black thread. I would not change the needle size unless hole size doesn't matter. You might only have to turn the top tension nut 1 turn to get the knots centered. Experiment on scraps first.

[MtlBiker]

26 minutes ago, Wizcrafts said:

Bonded nylon is almost always stiffer than bonded polyester thread. Black bonded thread is most always stiffer than other lighter colors. I asked a thread company about this and was told that they first dyed the raw thread dark blue, then black. This is why it was stiffer. That was in the late 1980s.

I used to use bonded nylon thread from Weaver. Some of the black spools had the thread coming off like a coil spring! I had to thread it counterclockwise through the top guide posts on machine I ran it through to counteract the twist. While still twisty, their white, chestnut and straw thread wasn't as hard to keep straight.

So, to answer your question, yes, you may have to change either the top or bottom thread tensions when switching from nylon to polyester thread, or possibly, from light colors to black thread. I would not change the needle size unless hole size doesn't matter. You might only have to turn the top tension nut 1 turn to get the knots centered. Experiment on scraps first.

We really need a LIKE button here.  Your posts are often such clear explanations and are very much appreciated.  This is just another example.

[TomE]

14 minutes ago, MtlBiker said:

We really need a LIKE button here.  Your posts are often such clear explanations and are very much appreciated.  This is just another example.

Agree with @MtlBiker.  I am grateful for the wisdom @Wizcrafts regularly passes along.   Thank you! 

[JLSleather]

5 hours ago, Wizcrafts said:

So, to answer your question, yes, you may have to change either the top or bottom thread tensions when switching from nylon to polyester thread

This has been my experience too, enough so that I try NOT to switch back and forth.  Wasn't always possible due to color availability, but turns out it was for the best.... a guy should learn how to make thes minor adjustments

 

[bland]

I do find it helpful to change my needle to a smaller size when using poly thread.  You may still have to make some minor adjustments to the tension as well.  

[kgg]

18 hours ago, Wyowally said:

Is a needle change ever necessary? I think I have found differences in the same brand of polyester thread, same size, different color that made me change bobbin tension.

 

18 hours ago, Wizcrafts said:

Bonded nylon is almost always stiffer than bonded polyester thread. Black bonded thread is most always stiffer than other lighter colors. I asked a thread company about this and was told that they first dyed the raw thread dark blue, then black. This is why it was stiffer. That was in the late 1980s.

I used to use bonded nylon thread from Weaver. Some of the black spools had the thread coming off like a coil spring! I had to thread it counterclockwise through the top guide posts on machine I ran it through to counteract the twist. While still twisty, their white, chestnut and straw thread wasn't as hard to keep straight.

So, to answer your question, yes, you may have to change either the top or bottom thread tensions when switching from nylon to polyester thread, or possibly, from light colors to black thread. I would not change the needle size unless hole size doesn't matter. You might only have to turn the top tension nut 1 turn to get the knots centered. Experiment on scraps first.

Just to add to the confusion.

i) V138: Bonded Nylon has an average manufactured thickness of 0.41 mm  while Bonded Polyester has an average manufactured thickness of 0.38 mm

ii) V138: Bonded Nylon has an average manufactured strength of 22 lbs while Bonded Polyester has an average manufactured strength of 21 lbs

iii) Bonded Polyester handles UV and bleach exposure better then Bonded Nylon.

kgg

[DonInReno]

If you measure various brands of thread, it’s quite amazing how much variation you’ll find in diameter and breaking strength.   I have a few spools of 207 that are no thicker than most of the 138 I’ve measured.    I’ve measured 90 weight that was probably produced as 100 or 110 for a large contract, but the leftovers can’t be sold as 138, so it’s sold as a fat 90.

I don’t know anything for certain, but it wouldn’t surprise me if some thread contracts were based on breaking strength - some thread has measured breaking strength over 50% higher than it should be for its size.   These are definitely made with stronger than average fibers.

 

[DonInReno]

On 3/17/2023 at 9:00 AM, Wyowally said:

Normally if you use 138 nylon or are set up for 138 polyester and use quality thread and want to switch, do adjustments just need to be tweaked a little? 

I seem to sew mostly with 138, even when I shouldn’t, and the type of 138 doesn’t make as much difference with tensions as the material thickness.   It’s rare that I’ll ever change bobbin tension - just a little more or little less tension depending on the project.   I can’t ever remember changing a needle for a different spool of similar size thread, but I tend to sew with a needle a little on the large size so it might not effect me as much as someone using a smallish needle.

[AlZilla]

Reading through this thread, I'm wondering if it might make sense to have 2 or 3 shuttle hooks, preset to different threads for these big machines?

[Wyowally]

Well folks - thanks!  I think I knew the answers but wanted to get the experts to give us the real lowdown on thread of the same size variations they've experienced. Is trolling for positive purposes and the benefit of others an acceptable thing?

[Wizcrafts]

11 hours ago, Wyowally said:

Is trolling for positive purposes and the benefit of others an acceptable thing?

YES!