| 50 × 18 × 256 | |
| = 18·3 courses per inch. | |
| 60 × 120 × 1·75 |
CHAPTER VI
Folded Yarns
An interesting series of calculations useful to the knitting industry can be built up in connection with the methods of finding the resultant single counts of two or more yarns folded together. The counts of twist yarns is in the first instance of special application to the spinner, but there are many circumstances in which they may be useful in the yarn store of a hosiery factory. When two yarns of the same counts are twisted, the resultant equivalent single counts is obtained by dividing by 2, but when the yarns vary in size the proceeding is rather different. A common fault is to add the two counts together and divide by 2, but this gives a result which is entirely wrong. For purposes of comparison it is useful to have the equivalent single counts when two or more yarns are folded together, but the special interest to this branch lies in using two single yarns to take the place of one, in cases where supplies of the first material have run short. It is then of practical importance to have the two substitute yarns chosen from those in stock so that they approach as nearly as possible the size of the original.
Example 27.—Find the counts of 60's and 40's folded together. This example can be used to build up the formula from first principles. Take for convenience 60 hanks of the highest counts and twist this with an equal length of 60 hanks of the second counts stated thus—
| 60 hanks of 60's counts weigh | 1 | lb. |
| 60 hanks of 40's counts weigh | 1½ | lb. |
| 60 hanks of folded thread = | 2½ | lb. |
therefore, 60 divided by 2½ gives 24 hanks of folded yarn in 1 lb. which is the counts 24's.
To find out a shorter rule for estimating the counts of a two-fold thread, let the first counts be represented by A, and the second counts by B, and let R be the resultant counts of yarns A and B folded together. Following the concrete example 27, it may be stated generally thus—
Example 28.—
| A hanks of A counts | = | 1 | lb. |
| A hanks of B counts | = | A⁄B | lb. |
| A hanks of folded yarn | = | 1 + A⁄B | lb. |
The resultant counts R is obtained thus—