What Twist Multiplier to Spin At

How to read this sheet

Read the two break columns against each other and ignore everything else. A tenth of twist buys a known amount of production, because delivery is exactly inversely proportional to the twist multiplier at a fixed spindle speed - no trial, no measurement, no argument. Divide that by what a break costs and you have how many extra breaks per hundred spindle-hours a tenth of twist may bring before it stops paying. The frame will tell you what it actually brings. Those two numbers side by side are the whole decision and they can be worked out on the back of the production report. Why the answer is so often a wash. A thousand spindles at eleven breaks a hundred spindle-hours is nine hundred thousand breaks a year, and moving the twist by a tenth moves that by a quarter. The production gained by twisting softer is very nearly eaten by the breakage it causes, which is exactly why the traditional multipliers have survived a century of nobody checking them. That is a finding and not a disappointment: it means the qualities where the answer is not a wash are worth finding, and they are not the ones anybody expects. The column nothing else will show you. A quality spun below the count strength product it is sold on does not appear in any realisation report, any efficiency report or any waste report. It appears in the weaver shed of a customer, months later, as a complaint about a lot that has already been paid for. Where the sheet reports it, the money it asks for is money that has to be spent rather than money that can be saved, and it should be read that way. What is not modelled. The strength curve is fitted from three points and the breakage line from two, so neither is trusted beyond the spacing of your own trials, and every quality held at that edge is reported rather than extrapolated - the action there is to run the trial and enter the result as the new middle. Nothing here values the fabric: a harder-twisted yarn weaves better and feels worse, and a customer who buys on handle will not thank you for the count strength product. Spindle speed is taken as fixed, where in truth a softer yarn may allow a higher one, which would change the answer in the direction of less twist. And hairiness, which is what actually decides how a yarn behaves in warping and weaving, is not on this sheet at all.