an Improved Grinding Machine. 339 



means a spindle or mandril to suit any sort of job may be used. 

 The stone is covered in by means of a wooden box, so that the 

 water used in grinding may not be thrown about the workshop. 

 The scale in Plate II. gives the dimensions of the parts of the 

 machines shewn in both plates. 



The machine shewn in Figs. 1, S, and 3 of Plate II. is one 

 for grinding pulleys round on the rim ; in all the Figs, the 

 same letters point out the same parts, a a is the grindstone ; 

 b his the pulley to be ground ; this pulley is fastened upon 

 the mandril or spindle c c. When a pulley to be ground is 

 put upon the mandril c c, or when a finished pulley is to be 

 taken off this mandril, the pincing screw d is slackened, and 

 then the ruff into which it is screwed gets loose upon the man- 

 dril ; after this the mandril is drawn on end, so far as that a 

 pulley may either be taken off, or put upon it, by taking hold 

 of the pulley e which gives motion to the mandril. The two 

 screws^/J^/y work into nuts fixed into the bracket g ggg-) and 

 by moving the handle or wheel A, the pulley to be ground is 

 pressed against the stone, or shifted away from it as is wanted. 

 The bracket gggg has two pins or gudgeons i i fixed on it, 

 and the frame II mm turns upon these pins as a centre. When 

 a pulley is to be ground very flat on the rim, the plummet- 

 blocks Jc Jc are shifted as close to the rail marked m mas they 

 can get, by turning the handle n. The closer that the plum- 

 met-blocks, into which the mandril c c works, are brought to 

 the rail 1 1, the pulley will be ground with the more curvature 

 on its rim. The shaft o o is set in motion, by means of the 

 bevel wheels p and g ; this shaft has an eccentric r upon it, 

 which, by means of the connecting rod s, gives motion to the 

 frame II m m. By slackening the pincing screw <, the eccen- 

 tric may be shifted along the shaft o o, and by slackening the 

 pincing screws u and v^ it may be shifted along the rod w w, 

 so as to give as much travel to the frame llmm asis required. 

 As the frame II mm is always in motion, it might perhaps be 

 better to have a guide round the pulley ^, in order to keep the 

 belt on it. After the plummet-blocks k Jc are brought to the 

 place on the rails of the frame II mm, which gives the pulley 

 its required curvature, the machine is set in motion, and the 

 pulley is pressed against the stone by means of the handle h. 



