(131) In setting, or, rather, in lowering the flats—because that is practically all that can be done by this arrangement—the bush is unlocked and the pin =J= taken out. It, with the wheel, is then lowered until the wires on the central flat and those on the cylinder can be heard to click. A careful note is taken of the amount which the bush has been lowered, and it is again raised to its central position and locked. Suppose that the amount was 1/250th inch—a very extreme supposition—then the distance the flats have to be lowered is that distance less 1/1000th inch, the standard distance between the wire teeth, or 3/1000th inch. The disc =K= is therefore revolved 1-1/2 times, which moves the cutters =G= inward to that extent, and, in consequence, the diameter of the wheel =D= is reduced, so as to provide a course for the flats of the exact size required. The cutters =G= are driven by a band from the cylinder shaft, and the wheels =C= are traversed as usual during the process of reduction. This arrangement is a novel one, but it is clear that, if successfully carried out, it provides a perfectly concentric flat course.
(132) Before proceeding further, and dealing with another form of machine, a few words may be said on the subject of setting the flats. It has been shown that in many cases a delicate indicator and micrometer screw is fitted, by which it is claimed the most exact settings can be made. There can be no dispute as to the power to do this which is thus provided, the only question is whether the circumstances of the case call for it, and whether in actual work any such accuracy is obtained and maintained. There are four points where adjustment is required in a carding engine. These are between the dish feed plate and licker-in; between the licker-in and cylinder; between the cylinder and flats or rollers; and between the doffer and cylinder. Messrs. Platt supply three gauges, respectively ·013, ·011, ·007 of an inch thick. The finest of these it will be seen is 7/1000ths of an inch thick, so that in this case at least the theory as to setting to 1/1000th is disregarded. In adjusting the flats, by far the commonest plan is to do so during the time the mill is standing, when everything is quiet. The bend is then dropped until the gauge which it is intended to use can be pushed between the two sets of teeth. If it is afterwards desired to get very fine setting, the bend is lowered until the slow revolution of the cylinder produces a “click,” which shows that the teeth of the cylinder and flats are in contact. A little elevation is given to the bend so as to leave a space between the teeth. A skilful setter can tell at any time by the “touch” of the teeth if they are too closely set, but the vibration existing during working hours may disturb his observation. When an indicator is used the practice is to establish the clicking point, and then turn back the screw until the flats are raised the desired distance.