To the lower end of the hooks (_c._ in Fig. V.) the neck-cords
are adjusted. The latter are passed separately through one of the
corresponding holes of the perforated bottom board (Fig. II.) To
these neck-cords are fastened the leashes of the Jacquard harness
about 1/2 to 1 inch above the frame containing the rods which guide
the neck-cords vertically as the hooks are raised and lowered. The
different harness-cords are threaded through the comber-board in
various ways called “Tie-ups,” which will be explained later.
The Comber-board and Methods of Figuring for it.
There are two kinds of comber-boards used upon Jacquard looms:
1st. Comber-boards made of a solid piece of material, either wood or
porcelain.
2d. Comber-boards made in strips of either of the materials above
named, and adjusted afterwards in a wooden frame.
Comber-boards Made of a Solid Piece of Material.
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.
Suppose we have a texture of 100 in the comber-board, to lower to 66
ends per inch. 66 ends, or the nearest even part of 100 (66-2/3) is 2/3
of 100; hence, we only need two-thirds of our machine; and as the same
is supposed to be arranged 12 rows deep, we need 2/3 of 12 rows, or 8
rows. The four rows thus found necessary to drop may be dropped from
the ends, or alternately, as follows:
Every alternate 2 rows taken, 1 row missed, 4 times over, = 12 rows.
Or, 2 rows missed, 8 rows taken, 2 rows missed, = 12 rows.
Comber-boards made in Strips and Adjusted afterwards in a Frame.
By these comber-boards which are used to a great advantage on narrow
loom work up to 36 inch fabrics, we can change the texture for the
fabric; for the strips composing the comber-board may be drawn
apart, thus changing the higher texture to lower; whereas in a solid
comber-board this could only be done by re-tying the harness or
changing the number of needles used in the machine. To give a clear
understanding Figs. XVIII., XIX., XX. are needed.
Fig. XVIII. represents an 8-row deep comber-board, _a_, _b_, _c_, _d_,
composed of 10 strips which are set close together. By examining each
strip 5 cross-rows of holes will be found, making the whole number of
holes 400.
Suppose the comber-board as represented in Fig. XVIII. is intended for
a texture of 100 ends per inch; this will give for the width of the
fabric (_i_, _k_, to _l_, _m_,) 4 inches.
[Illustration: Fig. XIX.]
[Illustration: Fig. XVIII.]
In Fig. XIX. the comber-board is arranged for a texture of half as many
ends, or 50 holes per inch, and the 10 strips are arranged accordingly;
the empty places between the strips are of same size as the strips
themselves, and the fabric design below the comber-board is arranged to
correspond.
[Illustration: Fig. XX.]
Fig. XX. illustrates the sectional cut of the comber-board used in
drawings, Figs. XVIII. and XIX., and the letters indicating the
different parts of these figures which correspond.
Divisions of the Comber-board.
Under this heading we classify one repeat of the arrangement of
threading harness-cords in the comber-board, and therefore one repeat
of the design of the fabric. We find fabrics in which are used one
or more divisions of one system of threading harness-cords in the
comber-board; again, there are others in which one or more divisions of
one system are combined with one or more divisions of another, or even
of two or three other systems.
Heddles for the Jacquard Harness.
[Illustration: Fig. XXI.]
After the harness-cords are threaded through the comber-board the
heddles are adjusted. Of these there are two kinds:
_A._ The twine heddle, containing the mail for holding the warp-thread.
_B._ The wire heddle, similar in its construction to the regular
heddle, used in the common harness-loom. These are very little used,
and only in fabrics of a low texture.
Fig. XXI. illustrates a regular twine heddle one-fourth of its actual
size.
_b_ represents the mail, through the eye of which the warp-threads are
passed.
_a_, the adjustment of the heddle to the harness-cord.
_c_ indicates part of the lingo for weighting the heddle.
[Illustration: Fig. XXII.]
Fig. XXII. illustrates the method observed for combining heddle and
harness-cords. _a_, the guide-board, to get the mails regular in
height; _b_, the knot combining heddle and harness-cord. [See _a_ in
Fig. XXI.] _c_, the mail. _d_, the lingo.
[Illustration: Fig. XXIII.]
Fig. XXIII. illustrates the average position of the mail in a loom.
_a_, breast-beam of the loom. _c_, the warp-beam or guide-beam over
which the warp runs on its way towards the harness. _b_, the position
of the heddle. _d_, the lingo.
The “Leasing” of the Harness.
[Illustration: Fig. XXIV.]
This requires a clear conception of the rotation in which the different
heddles are threaded, according to the tie-up employed. Two methods are
in use: 1st. The heddle nearest the weaver is the first to be threaded,
and the heddle of the same row in rear of the comber-board is the last.
2d. This principle reversed, thus arranging the leasing from rear to
front.
The latter method is the one most generally observed. Every row in
depth of comber-board is leased separately, and in rotation secured
to the lease-twines, _a_ and _b_, in Fig. XXIV., thus forming an
uninterrupted line of heddles through the entire Jacquard harness.
Through these heddles the warp is afterwards drawn in rotation.