PATTERN MAKING 



struction and the manner of using is necessary here. The four 

 parts of each hand screw consist of two jaws and two spindles. 

 When using, the jaws must in every case be kept parallel. This 

 is done by the adjustment of the middle or central spindle. The 

 clamping is in all cases done by the outside or end spindle, the 

 middle or adjusting spindle serving as a fulcrum for the jaws; the 

 leverage and pressure being obtained by the end spindle. When 

 clamping broad surfaces, care must be taken to see that the pressure 

 of the jaws on the work being glued is the same at the points and 

 at the back part of the applied portion of the jaws. 



This can be easily changed at will, by slightly loosening or 

 tightening the middle spindle, which, as before stated, is the 

 adjusting spindle and fulcrum, and not used for clamping. After 

 adjusting the jaws parallel and to even pressure on all their length 

 as applied to the work, screw up and tighten the end spindle to 

 the utmost pressure which the jaws will bear, and again examine 

 the clamp and the work to see 

 if the jaws are parallel and the 

 pressure even. 



If not, loosen the end spindle 

 and readjust the middle spindle 

 by opening or closing as the case 

 may require. To open and close the 

 hand-screws for larger or smaller 

 work, do not screw or unscrew 

 one spindle at a time. Instead, 

 grip the handle of the middle 

 spindle in the left hand, and the handle'of the end spindle in the 

 right hand. Hold the hand screw at arms length and whirl it from 

 or toward you as may be needed for closing or opening the jaws 

 In this way the spindles will each be kept in its proper relative 

 position, and the jaws will, at all distances, remain parallel. 



Fig. 158. 



BUILT UP PATTERNS. 



A good example of the manner in which patterns are built and 

 glued up is shown in the construction of the pattern for the 6-inch 

 sheave pulley shown in Fig. 158. 



