MACHINE-SHOP PRACTICE 



435 



causing the spindle which carries the cutter to revolve while 

 the table to which the work is fastened travels by. The 

 depth of cut can be regulated by the operator through the 

 medium of screws which raise or lower the knee upon which 

 the table is carried. The position of the cut is also controlled 

 by a screw which operates the lateral motion. 



502. Power Press. The power press is used for cutting 

 and forming sheet-rnctal parts. It has a strong base sup- 



FIG. 200. Grinding Machine. 



porting a crank shaft, which converts the rotary motion im- 

 parted by the pulley or fly-wheel into the rectilinear motion 

 of the gate or ram. A punch is fastened to the ram. and 

 carried by its motion through the die. The die is held 

 stationary in a chair or bolster plate. 



503. Grinding Machines. Universal grinding machines 

 (Fig. 200) are used for grinding pieces which have been dis- 

 torted by hardening, although it is sometimes profitable to 



