Improvements in Devices for Tapping Stay-bolt Holes.
Year: 1887

page_text: Improvements in Devices for Tapping Stay-bolt Holes.
1, JAMES T. CONNELLY, of Huntington, in the county of Cabell, and State of West
Virginia, United States of America, Boiler Maker do hereby declare the nature of my
invention for "IMPROVEMENTS IN DEVICES FOR TAPPING STAY-BOLT HOLES," and in
what manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
My invention relates to screw-taps for threading stay-bolt holes of locomotive fire
boxes, boilers, etc., where such stay-bolt holes are behind the frame of the boiler or
locomotive, without removing the frame or otherwise disturbing the engine.
Fire-boxes of locomotives are generally made of an inner and an outer metal sheet
or sheets, with a water space between them, and are held in place and securely braced
by numerous stay-bolts. The inside and outside shells of the fire-box are subjected
to great strain and wear, and the stay-bolts are, consequently, frequently broken or
become worn out and have to be replaced. Some of these stay-bolts are placed in
the fire-box behind the frame or other portion of the boiler, and, heretofore, to replace
one of these worn-out or broken bolts, it was necessary to remove the intervening
frame from the outside of the engine before a new bolt could be fitted in place. The
removal of the frame must be executed by skilled workmen, and is a tedious and
expensive operation and requires much time; and it is a well-known fact to those
skilled in the art to which my invention appertains that when the frame or other
part of the boiler or locomotive has been removed to replace a worn-out stay-bolt
which is located behind said frame, and then replaced again, the replaced frame or
part is never as strong as it was before being removed.

page_text: The object of my invention is to replace old stay-bolts with new ones without
removing the frame or otherwise disturbing any of the parts of the engine behind
which said bolts are placed, and this end I accomplish by first removing the old bolt
and then re-threading the stay-bolt hole from the inside of the fire-box, and by their
inserting a new stay-bolt from the inside of said box, which may thus be done quickly
and effectively at comparatively little expense and without injury to the frame-work
of the boiler.
The subject-matter claimed herein by me as of my invention is first described below,
and is then particularly pointed out at the close of this specification.
The accompanying drawings illustrate my improved apparatus, and in said
drawings:
Figure 1 is a view in elevation of a tubular screw-tap used for threading the stay-
bolt holes; and
Figure 2 is an end view thereof, looking at the rear, squared, or wrench end of
the tap.
Figure 3 is a view of a spindle or rod having an annular enlargement or shoulder
at one end for use with the tubular screw tap shown in Fig. 1.
Figure 4 is a view in clevation of another screw-tap used in another step of
threading the stay-bolt holes; and
'Figure 5 is a view of a spindle upon which said tap works; and
Figuro 6 is an end view of a circular nut which fits upon said last-mentioned
spindle.
Figure 7 is a sectional view of a portion of a locomotive fire-box, showing the inner
and outer shells of the fire-box, and illustrating my improved tools in different stages
of operation while threading stay-bolt holes, and also showing the relation the several
parts of the device bear to each other.
In carrying out my invention, I preferably make use of two tubular screw-taps,
A and B, the longitudinal bores, a, of which extend entirely through them, and these
tubular taps are fitted to work upon spindles or rods, C and E, respectively, the first
having an annular enlargement or shoulder, c, at one end, and the second rod or
spindlo, E, is provided with an annular nut fitted upon one end. The tubular
taps, A and B, are squared at one end, as at A' and B', for the application of a
wrench, as usual. The fire-box is shown as consisting of the usual inner and outer
shells, D and D', united at bottom by the usual bar, F, and it will be seen that some
of the stay-bolts, I, thereof are placed behind the boiler frame-work, (shown at G, G,);
and to replace a worn-out stay-bolt which is placed behind said frame, the frame, G,
has heretofore been removed.
To avoid removing the frame-work G, of the engine or boiler when it is desired
... to replace an old stay-bolt, and attain the consequent saving of time, labor, expense,
and injury to the engine, is the main object of my invention, which may practiced
as follows:
The workman, from the inside of the fire-box, first extracts the old bolt from the
hole into which it was first fitted and leaves the stay-bolt hole clear as at d and d
Fig. 7. The spindle, C, is now passed from the inside of the fire-box through the
hole, d, in the inside sheet or shell, D¹, until the enlarged annular end, c, of the
spindle, C, rests in the hole, d, of the outside sheet or shell, D, and against the frame-
work, G, which is opposite the hole, d, as shown in Fig. 7. The tubular screw-tap, A,
which is preferably a taper tap channelled as far as its threads extend, is now fitted
on the spindle, C, said spindle, C, passing through the longitudinal bore, a, of said
tap, and the tap, A, is turned by means of a wrench, as usual, placed on the squared
end, A', and cuts the thread in the walls of the hole, d, of the inside sheet or shell, D¹.
It will thus be seen that as the enlarged end, c, of the spindle, C, fits in the hole, d,
of the outside sheet or shell, D, and the screw-tap, A, fits in the hole, d', of the inside
sheet or shell D', the tap, A, is positively directed and guided in a right or straight
line relatively to the holes, d and d¹, as it threads the walls of said hole, d, and is
compelled to cut the thread of said hole in a right line with the hole, d, in the outer
shell D. When the hole, d, in the inner shell, D¹, is threaded, the spindle, C,

page_text: together with tap, A, is removed from the holes, d, d', and the spindle, E, is inserted
instead thereof with the tap, B, which is preferably a plug or straight tap with its
channels extending only about one-half as far as it is threaded, fitted thereon as
with the rod, C, and tap, A, as shown also in Fig. 7. The spindle or rod, E, is
externally threaded at one end, e, to receive an annular nut, H, working thereon.
Said spindle, E, with nut, HI, thereon, is, together with screw-tap, B, inserted in the
holes, d, d, until the threaded end, e, strikes or rests against the frame, G, while
the nut, H, (made preferably say of an inch wide) is half in and half out of the
hole d. The nut, H, thus placed, affords a firm bearing for the spindle, E, while at
the same time allowing the tap, B, to cut its thread in the wall of the hole, d, until
the end of said tap, B, touches said nut H, when by pulling the spindle, E, back and
turning it, the nut, H, is forced off the spindle, E, and drops down outside the fire-
box, and the tap, B, having now a firm bearing, is free to finish threading the hole, d,
of the outside sheet, D. Now with one end working in the hole, d, and the other
passing through hole, d', and guided by rod, E, the tap, B, is necessarily guided in
a straight line, and is forced to cut a thread in the hole, d, of the outside shell, D,
exactly corresponding as to pitch and coincidence to the thread of the opposite stay-
bolt lole, d, in the inner shell, D¹.
The advantages of using two taps, one a taper tap, A, and the other a plug or
straight, tap B, is that the taper tap first used easily cuts the thread in the hole, d',
of the inner shell, D¹, and prepares the way for the second or final plug tap, B.
The plug tap, B, is not channelled the entire length of its threads for the reason
that the end of the tap not channelled does not actually cut any thread, and having
its own thread entirely around it, it affords double strength for threading the walls
of the hole, d, in the outside shell, D.
The stay-bolt holes of both the inner and the outer shells of the fire-box having
thus been threaded without removing the frame-work, G, of the boiler or engine, or
otherwise disturbing the engine, and exactly corresponding one with the other,
constitute a perfectly-threaded hole for the reception of the new stay-bolt, which can
be inserted, in the ordinary manner, from the inside of the fire-box.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. The tubular screw-tap, substantially as described.
2. The combination of the tubular screw-tap having its bore extending its entire
length with a guide-rod upon which it works, substantially as described.
3. The combination of the screw-tap having a longitudinal bore therein with the
guide rod or spindle having an enlargement at one end thereof, substantially as
described.
Dated this 19th day of March 1888.