LATHE OPERATIONS - OD1645 - LESSON 1/TASK 1
center. Dead centers are always hard and must be lubricated very often to
prevent overheating.
(3) Pipe Center. The pipe center is very similar to the male center, but
its cone is ground to a greater angle and is larger in size. It is used for
holding pipe and tubing in the lathe while they are being machined.
(4) Female Center. The female center is conically bored at the tip and is
used to support workpieces that are pointed at the end.
(5) Half-Male Center.
The half-male center is a male center that has a
portion of the 60 cone cut away.
The half-male center is used as a
deadcenter in the tailstock where complete facing is to be performed. The
cutaway portion of the center faces the cutting tool and provides the
necessary clearance for the tool when facing the surface immediately around
the drilled center in the workpiece.
(6) V-Center. The V-center is used to support round workpieces at right
angles to the lathe axis for special operations such as drilling or reaming.
d.
Lathe Dogs.
(1) Lathe dogs (figure 19 on page 39) are cast metal devices used in
conjunction with a driving plate or a faceplate to provide a firm connection
between the headstock spindle and the workpiece that is mounted between
centers.
This firm connection permits the workpiece to be driven at the
same speed as the spindle under the strain of cutting. Frictional contact
alone, between the live center and the workpiece, is not sufficient to drive
the workpiece. Three common types of lathe dogs are illustrated in figure
19. Lathe dogs may have bent tails or straight tails. When the bent tail
dogs are used, the tail fits into a slot of the driving face plate. When
straight tail dogs are used, the tail bears against a stud projecting from
the faceplate.
(2) The bent tail lathe dog with a headless setscrew is considered safer
than the dog with the square head screw because the headless setscrew
reduces the danger of the dog catching in the operator's clothing and
causing an accident.
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