e turned, are so flexible that it is
necessary to support them at some point between the lathe centers. An
attachment for the lathe known as a steadyrest is often used for this
purpose. A steadyrest is composed of a frame containing three jaws _J_
(Fig. 19), that can be adjusted in or out radially by turning screws
_S_. The frame is hinged at _h_, thus allowing the upper half to be
swung back (as shown by the dotted lines) for inserting or removing the
work. The bolt-clamp _c_ holds the hinged part in the closed position.
The base of the frame has V-grooves in it that fit the ways of the lathe
bed. When the steadyrest is in use, it is secured to the bed by clamp
_C_, and the jaws _J_ are set in against the work, thus supporting or
steadying it during the turning operation. The steadyrest must, of
course, be located at a point where it will not interfere with the
turning tool.

[Illustration: Fig. 20. Application of Steadyrest to a Flexible Rod]

Fig. 20 shows the application of the steadyrest to a long forged rod,
having one small end, which makes it too flexible to be turned without
support. As this forging is rough, a true surface _n_ a little wider
than the jaws _J_ (Fig. 19) is first turned as a bearing for the jaws.
This should be done very carefully to prevent the work from mounting the
tool. A sharp pointed tool should be used and very light cuts taken. The
steadyrest is next clamped to the lathe bed opposite the turned surface,
and the jaws are adjusted in against this surface, thus forming a
bearing. Care should be taken not to set up the jaws too tightly, as the
work should turn freely but without play. The large part of the rod and
central collar are then turned to size, this half being machined while
the small part is in the rough and as stiff as possible. The rod is then
reversed and the steadyrest is applied to the part just finished, as
shown at _B_, thus supporting the work while the small end is being
turned. That part against which the jaws bear should be kept well oiled,
and if the surface is finished it should be protected by placing a strip
of emery cloth beneath the jaws with the emery side out; a strip of
belt leather is also used for this purpose, the object in each case
being to prevent the jaws from scratching and marring the finished
surface, as they tend to do, especially if at all rough.

If the work were too flexible to permit turning a spot at _n_, this
could be done by first "spotting"