154 (#210) ############################################ WOOLLEN AND WORSTED SPINNING 4 1 For 80 skeins under these conditions the mule would be making :- ·00863 x 80 x 256 = 1:54 draws per minute. 2 xбо These conditions are, of course, unthinkable. But these several methods of calculation and the results plotted in Figs. 48 to 51 will serve as a useful basis for exploration into problems of this type. 4. The more perplexing matter must now be con- sidered of the effect on output of the doffing-for as costs of running will usually be a fixed charge, the cost per lb. of spinning any yarn skeins will depend upon the weight-time” calculation, which should now be worked out on the following lines :- (a) Take the time necessary to doff one set (DT); (6) Calculate the time necessary to spin one set (T); (c) Calculate the output per hour by carefully considering the relationships of (a) and (b); thus :- (a) By actually timing a mule it is found that it takes 8 minutes to doff* (say 300 spindles). (b) Taking 20 skeins as an example, with '125 lb. per bobbin, the time taken to spin one set will be •125 X 20 X 256 = 106 minutes for spinning 1 set. 3 X 2 (c) The time (spinning and doffing) taken to spin I set (i.e. '125 lb. per spindle) will be :- * Approximately 60 per cent. of this time is for spindle - doffing and 40 per cent. for condenser-bobbin changing. If desirable, the two terms may be treated separately, but an addition of 66.6 to the spindle-doffing time is usually sufficiently near to the actuality for all practical purposes. In these calculations the two terms are this combined. 154
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