CHAPTER XXIII.

=EMERY WHEELS AND GRINDING MACHINERY.=

=Grinding Operations=; Classification of 38

The qualifications of emery wheels 38

Cements used in the manufacture of emery wheels 38

Grades of coarseness and fineness of emery wheels 38

Grades of wheels and the work they are suitable for 39

Speeds of emery wheels 39

Balancing emery wheels 39

=Emery Grinding Machines= 40

The Sellers drill grinding machine 41

The construction of the drill holding chuck 41

Varying the drill position to suit the diameter of the drill,

and thus maintain equal conditions for all diameters of

drills 41

Errors of construction in ordinary drill grinding machines 41

The construction whereby the Sellers machine maintains an equal

degree of clearance from end to end of the cutting edge upon

all sizes of drills 41, 42, 43, 44

The Sellers attachment for thinning the points of large twist

drills 44

The front rake of twist drills 44

Emery grinder for true surfaces 45

For engine guide bars 45

For car axle boxes 45

Emery grinder with traversing emery wheel 46

For rough work 46

For planing machine knives or cutters 46

Emery wheel swing frame for dressing large castings, &c. 46

Emery belt grinding machine 47

Presenting emery wheels to the work, or the work to the wheels 47

Annular emery wheels 48

Recessed emery wheel 48

The wear of emery wheels 48

=Polishing Wheels= 49 to 51

The construction of 49

Lapping the leather on 49

Method of keeping them true 50

Charging with emery 50

The speed of 50

Polishing materials for 50

Brush wheels for polishing 50

Speed of brush wheels 50

Polishing materials for brush wheels for brass work 50

Solid leather wheels 51

Rag polishing wheels 51

Polishing materials for rag wheels 51

Polishing device for engravers' steel plates 51

=Grindstones= and Tool Grinding 51

The various kinds of 51

Suitable for wood working tools 52

Suitable for saws or iron plates 52

The speeds of 52

The changes of pulley diameter necessary as the diameter of the

stone decreases in order to maintain a nearly uniform

circumferential speed of grindstone 52

Arrangement of, for saw plates 52

Hacking 53

Device for truing 53

Automatic traversing device for 53

Considerations that determine the position in which the work

should be applied to 53

=Oil-stones=, the various kinds of 54

Truing oil-stones 54

Removing the feather edge left by 54

Oil-stoning edge tools 54

Modern Machine-Shop Practice, Volumes I and II · 第 10 / 49 章