Hand Cards or a Drum Carder: Throughput, Cleaning Loss and the Fleece Weight at Which the Drum Pays for Itself

Carding is the bottleneck of hand spinning: an hour at the wheel consumes fibre that took far longer to prepare, and every spinner with more than a token fleece faces the same purchase question. Is a drum carder worth its price? Sellers answer with raw throughput figures; spinners answer with folklore about harsh treatment and wasted fibre. This paper computes both sides of the question in the same units: finished, spinnable fibre per hour for hand cards and for a drum carder at several speeds, charging the drum for the short fibre and nep loss that rises with speed, and then converts the time saving into the fleece weight at which the machine has paid for itself. In the computed results, the best rpm is 100; the best good g per h is 197.6; the best loss pct is 5.9; the hand g per h is 45; the speed multiple is 4.4. Run the drum at the speed that maximises good fibre per hour, not at its fastest setting, and buy the machine only if the fleece processed over its expected life clearly exceeds the computed payback weight. The study is simulated, not measured; all inputs are stated assumptions, printed in the accompanying computation, which readers may replace with their own values and re-run.