. Bulletin - United States National Museum. Science. ™T ™ Figure 16.—Screw press, 1822, for expressing vegetable oils, such as linseed. Restored patent drawing in Record Group 241, National Archives. these wrought iron rest bars, was a slight groove. From end to end in this groove was rolled a button end hand tool with so long a handle that the operator could rest it on his shoulder. I was often astonished at seeing the long curled shaving turned off in this primitive manner, and at the accuracy of the bolt turned, when tested by straight edge and calipers. [13] After a number of bolts of the
. Bulletin - United States National Museum. Science. ™T ™ Figure 16.—Screw press, 1822, for expressing vegetable oils, such as linseed. Restored patent drawing in Record Group 241, National Archives. these wrought iron rest bars, was a slight groove. From end to end in this groove was rolled a button end hand tool with so long a handle that the operator could rest it on his shoulder. I was often astonished at seeing the long curled shaving turned off in this primitive manner, and at the accuracy of the bolt turned, when tested by straight edge and calipers. [13] After a number of bolts of the same size had been turned, came the thread cutting, and this may be considered an advance or evolution from haphazard hand chasing and die cutting to the present engine lathe work, and even at this day will be looked at as an ingenious device. On the 3 inches of the over- hanging back mandrel was slid up against its collar what Mr. White called his "screw guide"; it was a template screw of the diameter and pitch of the screws he was about chasing, of about 4 inches in length on its thread; the portion projecting beyond the 3-inch overhanging mandrel was closed to a square hole in its center, into which the tit heretofore described on the end of the screw bolt would loosely fit. The carrying center of the back mandrel was a round steel rod about 8 inches long, perfectly straight beyond its pointed end. This center rod fitted in the center of the back mandrel, and was driven forward and held to its work by a wedge-key through a slotted hole in the mandrel. When the bolt on which the screw was to be chased was put in the lathe, the back head was driven forward by the wooden keys so as to bring it and the template firmly together; the back center was then driven forward by the key through the mandrel. By this arrangement the guide tem- plate was made to revolve with the screw bolt. The chasing tool—or, rather, tool carrier—was wrought iron, in form of a cross, w
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Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
