## To find the diameter number (D) of a yarn

## For firm yarns such as worsted wool and cotton

D = 0.9 x square root (yarn count x standard yards/lb)## For soft yarns such as woollen yarns and tweed yarns

D = 0.84 x square root (yarn count x standard yards/lb)

Ashenhurst's formula gives the maximum sett of a yarn. The formula

is based on:

## number of ends of warp in one repeat of the pattern

## number of times the weft passes from one side of the fabric to the other (intersections)

## the thread diameter number (D)

## Maximum sett = D x ends per repeat/(ends + intersections)

## Few cloths would be woven to this standard of firmness which gives

the maximum sett possible for a square cloth (with the same epi & ppi)

and the same yarn for warp and weft. A good working sett is about 3/4

of this number or slightly more## Example:

An 8/2 cotton has 2 plies of size 8 yarn, with a final count of 4.

It has 3360yd/lb (840yd/lb x 4).## D = 0.9 x sq rt(4 x 840)

= 52

Maximum sett (plain weave)

= 52 x 2/(2+2)

= 26## Maximum sett (2/2 twill)

= 52 x 4/(4+2)

= 34

Last updated: February 24, 1999