Thread size for sewing machines, can someone explain the numbers?

[jcuk]

On 1/25/2022 at 8:15 PM, JLSleather said:

Just when you thought it was safe to go back in the water.....
 

I have seen the "same size" thread from different manufacturers which were NOT the same size.  I mean, 227 from Co.A and 277 from CoB were NOT the same size... VISIBLY different, no micrometer needed.

 

I have noticed this with different brands hand stitching thread too. Some of the threads look like they are weight down from what they should be.

Hope this helps

JCUK

[kgg]

5 hours ago, Gymnast said:

Do you know what kind of threads these are?

I think they are using the " Gunze Count standard " where the larger the number the thinner the thread for a given number of ply. Those sizes would be typically seen at your local fabric store in those small domestic size spools. The number is referring to the weight of the thread but not the number of cords (piles) that make up the thread. Where a #30 2 ply isn't the same size as #30 3 ply but is labeled as #30 weight. Confusing??? From the needle size the machine should be able to handle correctly thread up to V69 (T70, Tkt 40).

kgg

[Gymnast]

On 1/25/2022 at 8:36 AM, Wizcrafts said:

Yes, you are correct. It is only on machines where one shuttle turns clockwise and the other counterclockwise that different thread twists are advised.

The Landis 12 series sole stitching machines all require right twist (waxed linen) thread. It's likely that other old shoe sewing machines have that right, or S twist requirement.

I think it needs to be the manufacturer of the machine, that make the S-twist requirement. I just noticed, that many normal machines using normal Z-twist thread got different direction of the hook relative to the needle. In the previously shown video, you got the hook approaching from right from needle perspective. I have looked at some of my machines and some other videos, and the direction of the hook vary:

Hook approach from right:
Singer 66, Singer 201, Pfaff 130, Pfaff 138, Singer 501a, Consew 206rb, Pfaff 545

Hook approach from left:
CB4500, Machines with CB-hook, Machines with long shuttle, Husqvarna Viking 6010 (and similar with double rotating vertical hook).  

So it seems that this decision for the designer of the sewing machines was not influenced by the preferred use of Z-twisted thread. 

I have tried to press a needle with thread through some vinyl and retract it a bit to simulate the loop forming. I think there is a tendency, that the thread gets locally twisted near the needle due to the friction against fabric, and therefore I see a tendency that the thread loop goes a bit to the right as seen in this picture, but you also have a significant variation on that every time you try:


 When you look this photo, you may prefer to have the hook from right. But I tend to believe, that this matter has little significance.