TRACING ATTACHMENTS
LATHE SETUP
Before an aircraft is permitted to take off, the pilot
A tracing attachment for a lathe is useful
and crew must go through a check-out procedure to
whenever you have to make several parts that are
determine whether the engines, controls, and safety
identical in design. A tracer is a hydraulically
features are in proper operating condition. The same
actuated attachment that carries the cutting tool on a
applies to an engine lathe. Part of this procedure is to
path identical to the shape and dimensions of a pattern
make sure the lathe is set up properly. Before starting
or template of the part to be made. The major parts of
a lathe machining operation, always make sure the
the attachment are a hydraulic power unit, a tracer
machine is set up for the job you are doing. If the
valve to which the stylus that follows the template is
work is mounted between centers, check the
attached, a cylinder and slide assembly that holds the
alignment of the dead center with the live center and
cutting tool and moves in or out on the command of
make any required changes. Ensure that the
the tracer valve hydraulic pressure output, and a
toolholder and the cutting tool are set at the proper
template rail assembly that holds the template of the
height and angle. Check the workholding accessory
part to be made. There are several different
to make sure the workpiece is held securely. Use the
manufacturers of tracers, and each tracer has a
center rest or follower rest to support long
slightly different design and varying operating
workpieces.
features. Tracers can be used for turning, facing, and
boring and are capable of maintaining a dimensional
LATHE SAFETY
tolerance equal to that of the lathe being used.
Templates for the tracer can be made from either flat
steel or aluminum plate or from round bar stock. It is
In machine operations, there is one sequence of
important that the template be exactly like the
events that you must always follow. SAFETY
finished part you require. Any scratch, dent, or
FIRST, ACCURACY SECOND, AND SPEED
mismachined dimension will be reproduced on the
parts to be made.
OTHER TYPES OF ENGINE LATHES
The type of engine lathe that has been described
in this chapter is the general-purpose, screw-cutting,
precision lathe that is universally used in the machine
shops of ships in the Navy. Repair ships also carry
other types. A short description of some other types
follows.
mounted on a bench. Such lathes are sometimes used
in the toolroom of repair ships.
has a removable bed piece shown on the deck in front
of the lathe. This piece can be removed from the lathe
bed to create a gap into which work of larger diameter
may be swung. Some gap lathes are designed so that
the ways can be moved longitudinally to create the
gap.
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