Section 13. qxd

Grinders
Grinding machines
may be classified as to purpose and type as follows:
for 
rough removal of stock,
the swinging-frame, portable, flexible shaft,
two-wheel stand, and disk; 
cutting off
or parting, the cutting-off
machine; 
surface finishing,
band polisher, two-wheel combination, two-
wheel polishing machine, two-wheel buffing machine, and semiauto-
matic polishing and buffing machine; 
precision grinding,
tool post,
cylindrical (plain and universal), crankshaft, centerless, internal, and
surface (reciprocating table with horizontal or vertical wheel spindle,
and rotary table with horizontal or vertical wheel spindle); 
special form
grinders, gear or worm, ball-bearing balls, cams, and threads; and 
tool
and cutter
grinders for single-point tools, drills, and milling cutters,
reamers, taps, dies, knives, etc.
1
⁄
4
1
⁄
10
7
⁄
8
3
⁄
4
Grinding equipment of all types (many with computer controls) has
been improved during the past few years so as to be more rigid, provide
more power to the grinding wheel, and provide automatic cycling, load-
ing, clamping, wheel dressing, and automatic feedback.
Centerless grinders
are used to good advantage where large numbers
of relatively small pieces must be ground and where the ground surface
has no exact relation to any other surface except as a whole; the work
is carried on a support between two abrasive wheels, one a normal
grinding wheel, the second a rubber-bonded wheel, rotating at about 
th
the grinding speed, and is tilted 3 to 8
to cause the work to rotate and
feed past the grinding wheel (see also Sec. 6).
The 
cylindrical grinder
is a companion machine to the engine lathe;
shafts, cylinders, rods, studs, and a wide variety of other cylindrical