“[Fig. 2833] explains the plan adopted for testing the strength of bolts and nuts in the same series of experiments.
Fig. 2834.
“A good holder for lathe-turned samples is shown in [Fig. 2834]. Close fitting socket-pieces b b embrace each end of the specimen, and also the turned collar at the extremity of the shackle a. The halves of the socket are held together by a collar c, the interior of which and exterior of the socket rings are turned to an equal taper, so that the socket-pieces are held quite firmly when the collar c is simply slipped over them by hand. When the experiment is over, a few taps with the hammer will remove the collar c.
Fig. 2835.
“Samples of plates for tensile testing are usually shaped like [Fig. 2835]. The parallel portion b is generally 8, 10, or 12 inches long, as in the case of the turned specimens. Two minor points in the preparation of specimens may be here alluded to. In the first place the holes a a must be made large enough to obviate any danger of the pins which are placed in these holes to secure the specimen being sheared in two before the specimen breaks. In the second place, enough material must be left around these pin or bolt holes to prevent the probability of the metal tearing away between the hole and the edge of the plate. The pin holes must be placed exactly in a line with the axis of the specimen, and the part b must be quite parallel in width, so that the strength (and the elongation during the testing) may be, as nearly as possible, equal throughout the length of b. The shoulders, as c, should be easy curves, so that sharp corners may be avoided. When a number of such specimens are required at the same time, the strips of plate may be clamped together and planed or slotted to the desired width as one piece, but the tool marks should be afterwards removed by careful draw-filing.