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Weaving Calculations · Lecture 03
Multiple Counts II – Yarns in Proportion
When the yarns are not present in equal numbers: weighting by the number of threads of each count.
Weighted meanThreads per count
From equal shares to proportions
Lecture 2 assumed one thread of each yarn. In a real warp a fabric may use 56 threads of one count for every 4.35 threads of another (a stripe, a selvedge, a cord). The rule is the same — add weights — but each yarn is weighted by its number of threads:
Mean Ne = Σ threads ÷ Σ ( threads / Ne )
“threads ÷ Ne” is proportional to the weight of those threads per unit length, so the denominator is the total weight and the numerator the total length.
Proportion worksheet
Four slots are provided; leave the threads of an unused slot at 0.
| A | B | C | D | |
|---|---|---|---|---|
| 1 | Yarn | Count Ne | Threads | Threads ÷ Ne |
| 2 | A | 1.8667 | ||
| 3 | B | 0.1450 | ||
| 4 | C | 0.0000 | ||
| 5 | D | 0.0000 | ||
| 6 | Totals | 60.35 | 2.0117 | |
| 7 | Mean count Ne | 30.00 |
blue = input (edit me)grey = formula (click to see it)
Try A = Ne 30 × 56 threads and B = Ne 10 × 4 threads: the mean drops to about Ne 25 even though only 7% of the threads are coarse. Coarse yarn dominates a weighted mean because it carries most of the weight.
Original lecture material
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