Before ordering a comber-board, it is necessary to know the texture of the fabric in the loom, and also the number or size of the machine to be used; for the number of holes per inch in the comber-board is regulated by this. Afterwards, we may, if we choose, arrange the number of holes in depth of the comber-board, according to the number of griffe-bars in the machine, (guided by the fabric to be made). We may have eight griffe-bars in the machine, and arrange the comber-board 4, 6, 8, 10, 12 rows deep; or we may have 12 griffe-bars in the machine, and arrange the comber-board 12, 10, 8, 6, 4 rows deep.
Rule: The number of holes to one inch in the comber-board must equal the texture of the fabric to one inch in loom.
Example: Suppose a fabric with a texture in the loom of 100 threads, and we are to use a 600 Jacquard machine, with 12 rows. The width of the fabric in the loom is to be 36 inches.
- Required: The number of holes in the width of the comber-board.
- Answer: 100 × 36 = 3600 holes in the comber-board.
- 3600 ÷ 12 = 300, the number of holes in width.
The width and depth of the comber-board are regulated by the width of the cloth required and by the design to be used.
The greater the number of rows in depth the closer they must be; the same is true of the width.
It is necessary to take care not to have the comber-board too deep, as the consequence would be a bad shed; furthermore, we must not have the holes too close together, as in a high texture this would make trouble in the weaving through the catching of the heddles with the warp, and also cause useless chafing of the warp-threads and the heddles.
The Changing of Solid Comber-boards for Different Textures.
In Jacquard work we generally use the same texture, or as near as possible, as the loom is tied up for; but changes are sometimes unavoidable. If we reduce the texture of the fabric in a Jacquard loom tied-up for a solid comber-board, we must reduce proportionally the number of hooks and needles used in designing, and hence the number of heddles used per inch. These heddles will thus be left empty when drawing in the warp. To accomplish this lift the full machine and throw the hooks not to be used from the knives, lowering in this way every mail which is not to be used. Sometimes there may be only one, two, three, or four hooks to be thrown off, on account of the design. At other times it may be necessary that one-eighth, or one-fourth, or even one-half of the whole number shall be dropped for this purpose. For instance, suppose we have a dressgoods design of 596 threads and a 600 machine. These four ends left off the 600, if in 6, 7, 8, or more inches in width, would not affect the fabric nor the cost to any great extent; hence we may leave out the first or last four needles of the 600.