Gauging thread length

[RonSC]

New guy here.. I've been loitering here for about a month and have to say this is a great forum with many knowledgeable and polite folks eager to help novice leather crofters like myself. KUDOS to admin folks for as well for well thought-out format. Thus far I've gleaned rafts of information from threads posted here.. Most of may projects are shooting/ hunting related , holsters, sheaths, belts, and rifle slings, but my work pales in comparison to most of the example I've seen here! One question I've had for years concerns how to gauge or estimate thread lengths for assorted projects so as not to

run out of thread and or to have an excess amount left over at the end of the stitching. I know this will be a function of the thickness of the work pieces as well as the thread size so there has got to be a way of estimating it within reason. Any help/suggestion in this regard would be greatly appreciated.

Again many thanks for a great forum..!

TIA,

RonSC

[RandyScott]

Hi RonSC,

I sat down one time and developed a ‘formula’ for calculating the thread requirements of a project and promptly forgot it! Here is the quick answer: Use an arm span of thread. It is recommended in Al Stohlman’s book “The Art of Handsewing” and it was recommended to me by a gentleman with 60 years leatherworking experience. Thread is cheap. The leatherworkers for hundreds of years used the same technique. If you think you will run out, cut the thread, get sufficient new thread, start with a few backstitches and finish the stitch line. It is better to have too much rather than not enough at the end of the stitch line!

Ok, now the formula!. WARNING: Your mileage may vary due to how tight you pull your stitches, the thickness or number of cords/ply and/or weight of the thread and any variance in the thickness of the leather used in the project. Final warning: I developed this for saddle stitching.

Needed: leather thickness in inches, i.e., .250” for example; stitches per inch; seam length in inches; and, the length of the “working end” of your thread, i.e., that part of the thread connected to the needle.

First, calculate the amount of thread needed for one linear inch: ((leather thickness X Stitches per inch) X 2) + 2. Now that you have the amount of thread needed for this thickness and stitches per inch for one inch, multiply this by the seam length in inches. This gives you a length of thread to sew the seam. Now add the amount needed for the 'working end' of the thread, i.e., when you finish the seam that amount to thread from leather to the needle and double this number (remember? Saddle stitching and two needles!).

For example: edge on sheath consisting of two 8 ounce leather = 16/64^ths or 1/4” or .250”, sewn at 5 SPI for a seam length of 6” and a working end of 12”.

((.250 X 5) X 2) + 2 = 4.5”

4.5” X 6” = 27”

27” + (12” + 12”) = 51”

The average man in 5’9” or 69” tall. A ‘span’ of thread is about 69”. So, I use the span method. You mentioned you do rifle slings. What is the seam length? Let’s be conservative, say 48”. 48 x 4.5 = 216” or 18 feet of thread to keep straight, untangled and clean.

The benefit to me of this exercise is that I now know that, for me, my rule of thumb (based on the projects I do) is 6” of thread per inch of stitching/seam. I know that anything less than a 8” seam is a span of thread. So my ‘unit of measure’ is 8” and thread length is in multiples of spans.

Hope this helps! Good luck…

[Leather Bum]

First, calculate the amount of thread needed for one linear inch: ((leather thickness X Stitches per inch) X 2) + 2. Now that you have the amount of thread needed for this thickness and stitches per inch for one inch, multiply this by the seam length in inches. This gives you a length of thread to sew the seam. Now add the amount needed for the 'working end' of the thread, i.e., when you finish the seam that amount to thread from leather to the needle and double this number (remember? Saddle stitching and two needles!).

That's an interesting formula. . . Thanks.

L'Bum

[RonSC]

Randy:

Many thanks for your explanation and formula. I was beginning to think that maybe this was (for the lack of a better word) a "dumb" question.. Usually it is not a problem for me except in "long" projects such as belts and slings. You have been a tremendous help.

Ron