LUBRICATION AND CARE OF THE SEPARATOR 225 



times covered with smoke or painted with white lead or 

 graphite as a substitute for paper. The usual shop practice 

 in manufacturing is to use a mandrel or arbor from one- 

 one-hundredth to one-sixty-fourth of an inch larger than 

 the shaft to be run in the bearing. 



Before pouring the box, block up the shaft until it is 

 in line and in center of the box and put stiff putty around 

 the shaft against the ends of the box to keep the babbitt 

 from running out. Be sure to leave air-holes at each end 

 on top, making a little funnel of putty around each. Also 

 make a larger funnel around the pouring hole, or, if there 

 be none, enlarge one of the air-holes and pour into it. 

 These putty funnels should extend a little above the box so 

 as to give pressure to the babbitt and to allow the metal 

 to fill in, as it shrinks in cooling. The metal should be 

 heated until it just hot enough to run freely and the fire 

 should not be too far away. It injures the metal to over- 

 heat it or to allow it to remain in a molten state without 

 stirring. When the metal becomes hot enough to brown 

 a white-pine stick, or when it begins to change from a 

 silvery to a yellowish tinge, is the best time to pour. When 

 ready to pour the box, do not hesitate or stop, but pour con- 

 tinuously and rapidly until the metal appears at the air 

 holes. The oil hole may be stopped with a wooden plug 

 and if this plug extends through far enough to touch the 

 shaft, it will leave a hole through the babbitt so that it will 

 not be necessary to drill one. 



15 



