Thread Length Per Thickness And Stitch Length

[tboyce]

I used to have a hard time trying to figure out how long of a piece of thread I needed for hand stitching so I worked up this handy spreadsheet to help me estimate.

Thread Length.pdf

[tboyce]

I forget sometimes that I work these things up for myself and they might not be easily understandable by others.

The Stitched ounce column refers to the total thickness of leather stitched. For instance, 2 refers to (2) 1oz layers of leather. 12 is (2) 6 oz pieces or (3) 4oz pieces

The numbers in the blue row refer to stitch lengths I have pricking irons for 1/8" 3/32" 7pi and 10pi

The numbers in the white represent the corresponding length of thread required per stitched inch.

For instance, if I were stitching a 36" belt and the total leather thickness is 12 oz. and I were using a 7p1 pricking iron to mark the holes, I would require 180 inches of thread per side of the belt.

Edited October 28, 2014 by tboyce

[DavidL]

How did you come up with the answers I'm interested.

the white column is for the whole length of the thread or half?

By 7pi do you mean 7 TPI or 7 SPI.

With thicker thread It would use more length than thinner thread, did you work out the ratio?

This would come in handy when you need to use 3 threads of stitching on the entire piece and can figure out how much to use without excessive waste.

The way of figuring out how many lengths of the stitch line can work too. Could be something you can work into a side chart. I hear 3-4 times the length of the stitch is enough for 7 SPI. Sometimes I fall short because I often forget about thickness of leather and of thread size.

[tboyce]

Didn't take the tread thickness into account. I just worked it out on the computer. I'm not sure how much of a factor thread thickness is but I just use this as a guide and round up a little. It never fails me

The pi is tpi by the way

[zuludog]

Why so complicated?

I worked out quite early on that on saddle stitching I needed the thread to be 5 to 5 1/2 times the run or length of the line of stitching. This allows for back sewing 3 or 4 holes to secure the thread

I use that calculation for any thickness of leather or pitch of the holes

Thread is so cheap compared to the rest of the work that you can afford to be a bit generous

Interestingly, in your example, 180 divided by 36 equals 5

[tboyce]

Good rule of thumb. I never was able to find one so the engineer in in me set out to figure it out and apparently overcomplicate it along the way

[DavidL]

Its to prevent using too short a thread. In the beginning you find out using X3 the amount of thread for a 2 inch stitch line is too short.

if you can calculate it you can take away the guesswork and risk having to restitch the entire piece or use a new thread.

btw how did you come up with those numbers? what was the formula?

[tboyce]

I put put the various thicknesses on a cad drawing, drew a polyline simulating the path of the thread through various stitch lengths for an inch, queried the length of the polyline and doubled it, (because its a saddle stitch) then rounded up to the nearest 16th of an inch. Then I just stretched the polyline to simulate the various leather thicknesses and reran the query....took about 15 minutes but I figured it would be a time saver

[zuludog]

Definition of an engineer

2 + 2 = 3.99 or better

[tboyce]

lol

[billybopp]

ROFL @ zuludog.

Now .. tboyce ... How do you run the same sort of calculation with a cast thread saddle stitch? That lil' ol' knot down in the hole does take up some additional amount of thread.

Bill

[tboyce]

That's why we round up

[JLSleather]

As a rule, crossing the street takes longer than NOT crossing the street, by an amount directly inversely proportional to the speed of the traveler.

Edited October 29, 2014 by JLSleather