it at some point _o_, and placing the
steadyrest at that point while turning another spot at _n_.

Sometimes it is desirable to apply a steadyrest to a surface that does
not run true and one which is not to be turned; in such a case a device
called a "cat-head" is used. This is simply a sleeve _S_ (Fig. 21) which
is placed over the untrue surface to serve as a bearing for the
steadyrest. The sleeve is made to run true by adjusting the four
set-screws at each end, and the jaws of the steadyrest are set against
it, thus supporting the work.

[Illustration: Fig. 21. Cat-head which is sometimes used as Bearing for
Steadyrest]

=Application of Steadyrest when Boring.=--Another example illustrating
the use of the steadyrest is shown in Fig. 22. The rod _R_ is turned on
the outside and a hole is to be bored in the end (as shown by dotted
lines) true with the outer surface. If the centers used for turning the
rod are still in the ends, as they would be ordinarily, this work could
be done very accurately by the following method: The rod is first placed
between the centers as for turning, with a driving dog _D_ attached, and
the steadyrest jaws _J_ are set against it near the outer end, as shown.

Before any machine work is done, means must be provided for holding the
rod back against the headstock center _h_, because, for an operation of
this kind, the outer end cannot be supported by the tailstock center;
consequently the work tends to shift to the right. One method of
accomplishing this is shown in the illustration. A hardwood piece _w_,
having a hole somewhat larger than the work, is clamped against the dog,
in a crosswise position, by the swinging bolts and thumb-screws shown.
If the dog is not square with the work, the wood piece should be canted
so that the bearing will not be all on one side. For large heavy parts a
similar "bridle" or "hold-back"--as this is commonly called--is made by
using steel instead of wood for the part _w_. Another very common method
which requires no special equipment is illustrated in Fig. 23. An
ordinary leather belt lacing _L_ is attached to the work and faceplate
while the latter is screwed off a few turns as shown. Then the lacing is
drawn up by hand and tied, and the faceplate is screwed onto the
spindle, thus tightening the lacing and drawing the work against the
headstock center. The method of applying the lacing is quite clearly
indicated in the illustration. If a small driving facepl