Double Threading A Needle On Cowboy Machine?

[Divafnk]

I'm currently taking a fabric sewing class that shows that one can double thread a needle (with two spools of thread-two strands of thread going through the needle) to get a thicker looking stitch.

I'm assuming that since this can be done on your regular fabric sewing machines that I can also do this on my Cowboy? Does anyone know either way?

Thanks in advance!

[Wizcrafts]

Why not just use a larger size needle and thread to start with? My CB4500 can handle up to #415 thread. That is almost 1mm in diameter.

[Divafnk]

I've thought about that as well.

I've read several articles on the needle sizing numbers and still can't figure out what the two numbers mean at all.

[Wizcrafts]

I've thought about that as well.

I've read several articles on the needle sizing numbers and still can't figure out what the two numbers mean at all.

Thread #277 is very close to .5mm in diameter. It takes at least a #24 needle to pass that thickness freely. In practice, the hole a #24 needle makes is sometimes a bit too narrow to bring the knot from the bottom thread well up into the bottom layer. It depends on how dense the bottom leather or material happens to be. So, most of us with a 441 type machine will use a #25 needle, which definitely pokes a wide enough hole for both the top and bottom thread to move as required.

The relationship between various needles and thread is demonstrated on the needle and thread chart on the Toledo Industrial Sewing Machines website. You can use it to select the best needle for any given size of thread in common use.

[Divafnk]

Thanks for that link! Something that confuses me is the way the needle sizes are written. "12/80". What does the 12 mean, and what does the 80 mean?

[VanRhodes]

The first digits, 12 in this case is the US-size of the needle, whilst the second is the metric size, nm:80 in this case.

[Wizcrafts]

The 12/80 size needle is typical for cotton thread sewn into broadcloth, shirts and ladies skirts. A #12 needle cannot be used in normal leather work, or on a 441 type machine, like a CB3200. But, amazingly, it might be used by a Western boot maker (in a post or flat bed machine) to sew decorative patterns onto boot uppers with #33 bonded nylon thread.

Actually, the first number is not just a US designation. It was the sizing system developed by the Singer sewing machines company, more than a century ago.

A 441 type machine uses system 7x3 round point and 7x4 (794) leather point needles. The smallest size I have been able to get are #19/120. These needles are so long that the thin shank on a #19 is easily deflected and extreme caution is needed to avoid bending or breaking them. I use them to sew with #92 bonded thread, which I found to be the practical lower limit for my CB4500 and for a Cobra Class 4. Sometimes I can get #69 to sew, but it requires so many readjustments to the tensioners and check spring as to be impractical. Rather, I use other machines (patchers) for such minute thread.

[TwinOaks]

My concern with double threading is since there's only one set of tensioners...how do you assure that both threads are evenly tensioned? I can see it being quite possible for one thread to slide past the other, and leave you with loose stitches or worse...a birdnest in the hook case.

[Wizcrafts]

I cannot imagine why somebody with a machine capable of sewing with #346 or 415 bonded thread would even want to sew two #138 stitches instead. #415 thread is almost 1 mm thick. The tensile strength is almost 60 pounds per stitch. #138 thread only has 22 pounds breaking strength. Double stitched, you get two rows of 22 pounds strength. The best that can provide would be 44 pounds combined. One stitchline with #277 thread accomplishes the same strength, with less to go wrong.

[Tramps Leatherworking]

Divafnk,

Just use a larger needle and thread, even if you could somehow pull it off, what would be the purpose? As already stated, those machines will sew very heavy thread...