. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. now carried to the other two pairs of rollers in the rollmgmill which are made of case-hardened iron, and better polished than the hreaking-downrollers The plates are passed cold between these, to bring them to exactly the samethickness; whence thev are called adjusting or planishing rollers. The workman heretries every piece by acommon gauge, as it comes through. This is a piece of steelhavin<^ a notch in it; the inside lines of which are very straight, and inclined to oneanothe
. A dictionary of arts, manufactures and mines : containing a clear exposition of their principles and practice. now carried to the other two pairs of rollers in the rollmgmill which are made of case-hardened iron, and better polished than the hreaking-downrollers The plates are passed cold between these, to bring them to exactly the samethickness; whence thev are called adjusting or planishing rollers. The workman heretries every piece by acommon gauge, as it comes through. This is a piece of steelhavin<^ a notch in it; the inside lines of which are very straight, and inclined to oneanother at a very acute angle. They are divided by fine lines, so that the edge of theplate being pressed into the notch, will have its thickness truly determined by the depthto which it enters, the divisions showing the thickness in fractions of an inch. In rollin the plate the second time, all the plates are successively passed through therollers • then the rollers being adjusted, they are passed through another time. Thisi« repeated thrice or even four times; after which they are all tried gauge, and. MINT. 867 thus sorted into as many parcels as there are different thicknesses. It is a curious cir-cumstance, that though the rollers are no less than 14 inches in diameter, and their frameproportionally strong, they will yield in some degree, so as to reduce a thick plate in aless degree than a thin one ; thus the plates which have all passed through the samerollers, may be of 3 or 4 different degrees of thickness, which being soiled by the gaugeinto as many parcels, are next reduced to the exact dimension, by adapting the rollers toeach parcel. The fust of the parcel which now comes through is tried, by cutting out acircular piece with a small hand machine, and weighing it. If it proves either too lightor too heavy, the rollers are adjusted accordingly, till by a few such trials they are foundto be correct, when all the parcel is rolled through. The trial plates which tur
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Keywords: ., bookcentury1800, bookdecade1840, booksubje, booksubjecttechnology
