FORMS OF SPECIMENS. 



133 



is a specimen cut from a steel or iron j)late, and provided 

 with enlarged ends and pin holes for fixing in the machine ; 

 this form is practically obsolete. At B is shown a much 

 more usual form ; in fact, what may be called the standard 

 form for plate specimens. Here a piece about 20 in. long 

 and 2J in. wide is cut from the plate ; this is afterwards 

 shaped in the manner shown, so as to leave about 12 in. 

 between the shoulders, the narrow part being left about 1 J in. 

 wide ; there is thus left a clear length of 10 in. to be used" for 

 measuring purposes. 10 in. is the best length to be 



Grips for Plate Specimens. 



FIG. 64.* 



employed, although other lengths are used by some experi- 

 menters. In making flat test bars of this kind it is most 

 important to avoid sharp corners, where the shoulders are 

 formed, and to have them rounded, as shown in the sketch. 

 The shaping of the bars may be done in a shaping, 

 milling, or planing machine. Where a large number of 

 the same size have to be prepared at the same time, they 

 can be put into a shaping machine, in a batch, and a 

 cut taken right across them. A cheaper form than the last, 

 and one more easily prepared, is shown at C. It is a 

 plain parallel strip, with no reduction in the middle. The 



*Inst. Mech. Eng., 1898. 



