Recommended Stitch Length

[Ed the Hunter]

Is there a general rule of thumb when it comes to choosing the correct stitch to use on your machine.  For example is it based on the strength or thickness of the two pieces of leather you are joining, or is it purely for cosmetic reasons.  I have spoken to people at sewing centers, leather shops, and sewing machine service reps and nobody seems to be able to give me a straight answer.

Thanks

Edited October 3, 2019 by Northmount
Fixed title to fit subject

[mikesc]

Depends entirely upon what you mean by "the correct stitch"..do you mean thread type, or thread thickness, or stitch length or stitch type..or combinations of some, or all of those things. ? Not all "machines" can do all types of stitches, nor can all machines handle all thicknesses of thread. There are some types of thread that some machines like more than others, and some types of threads that only certain machines can sew with..Some machines were designed to do certain things to the thread, such as waxing it or oiling it or adding silicone while the thread was being used on the machine..

 

You cannot get a "straight answer" ..there is no "one size fits all" answer ..when it depends so much upon what you mean by the question..like most questions in life :)

[Ed the Hunter]

I have a Juki walking foot and it knows exactly what type of threads it likes.  I am asking specifically how to determine the correct stitch length.  when you look at a leather jacket for instance, it is generally short delicate looking stitch, horse tack on the other hand is more often than not had stitched with a heavier thread an a longer stitch pattern.  Belts and dog collars on the other hand can be found with any  of a variety of stitch lengths. Is this determined by the thickness of the thread, the thickness of materials etc. and if so, what is the basis of the decision?

[Northmount]

Have you done a search here for existing threads?

Here are 2 that I found in a quick search.  https://leatherworker.net/forum/topic/53981-needle-size-thread-spi-and-leather-weight-rule-of-thumb/?page=2

https://leatherworker.net/forum/topic/55351-ideal-stitch-length-for-specific-thread-size/

Tom

[Ed the Hunter]

I did do a search, but I missed those.  Thank you.

[mikesc]

Quote

Is this determined by the thickness of the thread, the thickness of materials etc.

IME..the stitch length..and to a degree, the thread used..is down to aesthetics. Especially on garments..

In your case, it will also depend on which "Juki walking foot" machine, there are / have been many different ones, with different specifications and different capabilities.. ?, They can't all sew with the same threads, they can't all sew the same stitch lengths.

[Gymnast]

If you make a search by Google, you will be able to find technical research done on the matter, with pull tests of seam strength for different cases.

With leather, you will normally cut holes in it to make way for the needle and thread. Therefore a short stitch length causes the leather to get weaker at the seam. In this case the seam strength will be determined of the remaining strength of the leather. On the other hand when you have a long stitch lenght, the strength of the thread may deside how the strength of the seam will be.

Woven fabric will normally not be weakened much by the needle, because the fibres in the fabric is just pushed a Little to the side and remains intact. Therefore a short stich length do not cause quite the same problems for strengt.

In most cases I should think, that the stich length is desided by the looks, and how the manufacturer feels about it, and from some experience.