Improvements in Devices for Tapping or Screwing Holes.
Year: 1891

page_text: COMPLETE SPECIFICATION.
Improvements in Devices for Tapping or Screwing Holes.
I, JAMES THOMAS CONNELLY, of Milton, in the County of Northumberland
and State of Pennsylvania, United States of America, Foreman of Car Works,
do hereby declare the nature of this invention and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :---
This invention relates to screw-tap devices for threading stay-bolt holes; and the
object of my present invention is to provide a simple and improved device of this
character which will be especially adapted for long distances-as, for instance, from
the outer shell to the crown-sheet or from side to side of shell in locomotive
engines and which will, furthermore, possess advantages in point of simplicity and
inexpensiveness in construction, convenience and facility in use, ease and perfection
of operation, and general efficiency.
To this end my invention consists in certain improvements in the class of tapping
devices covered by my Patent, No. 18,034, granted August 18, 1887, and my
invention further consists in general features of construction and arrangement,
substantially as will be hereinafter fully described, and particularly pointed out in
the claims.
In the drawings-
Figure 1 is a side elevation of my improved screw-tap devices for long distances.
Figure 2 is a longitudinal sectional view of the same.
Figure 3 is an end view.
Figure 4 is a transverse sectional view on the line, Figure 2.
Figure 5 is a transverse sectional view on the line y y, Figure 2.
Figure 6 is a transverse sectional view on the line zz, Figure 2.
Figure 7 is a side view of the spindle.
Corresponding parts in all the figures are denoted by the same letters of
reference.
In my previous Letters Patent above noted, I have shown a tubular screw-tap
having a smooth bore which receives a corresponding smooth rod or spindle, upon
which the tap is mounted and by which it is guided during operation. This con-
struction and arrangement of tapping devices was especially adapted for use in
cases where the stay-bolt holes are behind the frame of the boiler or locomotive,
in which case the guide-rod was placed with its end against the inner face of the
frame-work, and the tap operating from the inside was guided by the rod and
operated to tap the bolt-holes in both the inner and outer shells without removing
the frame or otherwise disturbing the engine. This arrangement of tapping devices,
while very effective under usual conditions, is not particularly adapted for tapping
stay-bolt holes in long distances, and my present improvements are therefore
designed to provide an improved tapping device of the character set forth in my
above mentioned Letters Patent which will be especially adapted for convenient
and effective operation under conditions involving long distances, and by the

page_text: employment of which the operation of tapping can be more rapidly and economically
accomplished
Referring to the drawings, A designates two corresponding screw taps provided
with exterior threads a, and having a central bore B, longitudinally disposed and
preferably extending entirely through the tap, this bore being threaded at b, as
shown. The internally and externally threaded tubular screw-taps thus formed
are provided with an angular outer end a', for the application of a wrench, in the
usual manner, and may be otherwise of any suitable or preferred construction.
C designates the spindle, which is externally threaded at c, to correspond to the
threaded bore B of the taps. This spindle may be of any desired length, and upon
it are mounted the screw-taps A A, one at either end, as shown, the taps being
thus adapted to work upon the threaded spindle toward each other and be perfectly
guided thereby. It will be noticed that the spindle is threaded its entire length,
and that the spindle, preferably, has the same pitch or thread as the taps, whereby
the spindle serves to perfectly guide the taps in a straight line and effect a perfect
relative operation as the threads are cut in the respective bolt-holes.
In the manufacture and use of my improved tapping devices it will be noted that
the taps can be made in various sizes, while the spindles may be of uniform size, thus
enabling taps of any size to be used and operated upon the same sized spindle, and
that the size of the taps is regulated by the diameter of bolt-holes to be threaded,
while the length of spindle will be regulated by the longest distance between
the sheets, the diameter of the spindle being the same in any length of spindle
or for any size of tap.
In the operation of the herein-described improved screw-tap devices for long
distances, one of the taps is first screwed upon the spindle far enough to have a
firm bearing. The spindle is then passed into the holes to be threaded until the
end of the tap enters the adjoining sheet, and the other end of the spindle extends
or projects far enough from the hole in the other sheet to receive the other tap.
The other tap is then screwed upon this projecting end of the spindle, and the two
taps are both run into the sheets and the bolt-holes threaded by the application of
a wrench, in the usual manner. These improved devices are adapted to be used by
two men at the same time, the devices being capable of simultaneous operation upon
the bolt-holes in both sheets.
By reason of this improved construction and arrangement of internally and
externally threaded taps mounted at opposite ends of a screw-threaded spindle
having its threads of the same pitch as those of the taps, it will be apparent to all
those skilled in the art to which my invention appertains that the taps are relatively
guided in a perfectly straight line, even in tapping for long-distance holes, while
the threads are perfectly cut in the walls of the bolt-holes in the respective sheets
to exactly correspond one with the other and provide relatively perfectly threaded
and centred holes for the reception of the stay-bolts.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what
claim is
1. An internally threaded screw tap, substantially as and for the purpose set
forth.
2. A screw tap having a central longitudinal bore threaded its entire length,
substantially as and for the purpose set forth.
3. The combination, with a threaded spindle, of a screw tap having a central
bore and internally threaded, the internally threaded screw tap being adapted to
work upon the screw threaded spindle, substantially as and for the purpose set
forth.
4. The combination, with a spindle threaded its entire length, of a screw tap
provided with a central longitudinal bore and internally threaded its entire length,
said internally threaded tap being adapted to receive the threaded spindle and work
upon the same, substantially as and for the purpose set forth.

page_text: 5. In a device for tapping long distance stay bolt holes, the combination, with a
threaded spindle, of screw taps oppositely mounted upon the spindle and having
a screw threaded bore receiving the same, substantially as and for the purpose
set forth.
6. In a device for tapping long-distance stay-bolt holes, the combination, with a
spindle screw threaded throughout its length, of screw taps oppositely mounted
upon the spindle and having a central longitudinal bore screw threaded throughout
its length and receiving the corresponding spindle, substantially as and for the
purpose set forth.
7. In a device for tapping long distance stay bolt holes, the combination, with the
spindle threaded throughout its length, of screw taps oppositely mounted upon the
ends of the spindle and provided with a central longitudinal bore screw threaded
throughout its length, the threads of the spindle having the same pitch as the taps,
substantially as and for the purpose set forth.
8. The combination, with a threaded spindle, of an internally and externally
threaded screw tap, substantially as and for the purpose set forth.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.