A New or Improved Tool or Appliance for Cutting Screw Threads in Hollow Articles of Clay or other Soft Material.
Year: 1895

page_text: Date of Application, 14th July, 1805
Complete Specification Left, 1st Apr., 1896-Accepted, 16th May, 1896
Date Application, I busy,
Complete Specification Left, 1st Apr., 1896-Accepted, 16th May, 1896
PROVISIONAL SPECIFICATION.
A New or Improved Tool or Appliance for Cutting Screw Threads
in Hollow Articles of Clay or other Soft Material.
We, BULLERS LIMITED, of Sherlock Street, Birmingham, in the County of Warwick,
Telegraph Engineers and Manufacturers, and JOHN THOMAS HARRIS, of The Radfords,
Stone, in the County of Stafford, Manager of Works, do hereby declare the nature of
this invention to be as follows:-
The said new or improved tool or appliance consists essentially of a tool holder or
handle preferably of wood from one end of which projects a cylindrical metallic stem
or rod. At or about the middle of the said stein a projecting screw thread is formed
the pitch of the said thread being the same as that which it is desired to cut in the
hollow articles to be operated upon. On this screw threaded portion of the stem, a
tubular screw box or bush works, the said screw box being conical externally the base
of the cone being towards the handle end of the tool. To the extreme end of the
stem the screw thread cutter or tap is attached, the acting end or point of the cutter
or tap being V shaped, square or of a figure the counterpart of that which it is
desired that the screw thread to be made shall have.
In using the new or improved tool or appliance described, part of the article to be
screw threaded or tapped is bored out to fit the conical screw box or bush on the
screw threaded portion of the stem of the tool. The article to be operated upon is
rotated in the chuck of a lathe and the tool with its screw box at the front or com-
When the screw box
mencing end of the screw is presented to the said article.
comes in contact with the part of the article bored out to receive it, the said screw
box rotates with the said article and the workman holding the tool by its bandle
prevents its rotation but permits it to advance in the line of its axis. The said tool
with its cutter or tap consequently advances into the rotating article at a rate proper
to cut an internal screw thread of the same pitch as the thread on the stem of
the tool.
Although we have described the rotating of the screw box by connecting it directly
with the article under operation yet we wish it to be understood that the said article
may be connected to the screw box by a separate appliance rotating with the work
in the chuck.
And although we have described the carrying of the article under operation by the
rotating chuck of a lathe and the application thereto of a non-rotating tool yet we
wish it to be understood that the said tool may be fixed in the chuck of the lathe, the
article under operation and the screw box on the screw of the tool being held during
the formation of the internal screw thread.
D
Dth dex of July 1895
W. T. WHITEMAN,
Agent for the Applicants.

page_text: i
A New or Improved Tool or Appliance for Cutting Screw Threads
in Hollow Articles of Clay or other Soft Material.
We BULLERS LIMITED, of Sherlock Street, Birmingham, in the County of Warwick,.
Telegraph Engineers and Manufacturers, and JOHN THOMAS HARRIS, of The Radfords,
Stone, in the County of Stafford, Manager of Works, do hereby declare the nature
of the said invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
or rod.
The said invention consists of the new or improved tool or appliance hereinafter
described for cutting screw threads in hollow articles of clay or other soft material.
The said new or improved tool or appliance consists essentially of a tool holder or
handle preferably of wood from one end of which projects a cylindrical metallic stem
At or about the middle of the said stem a projecting screw thread is formed,
the pitch of the said thread being the same as that which it is desired to cut in the
hollow articles to be operated upon. On this screw threaded portion of the stem, a
tubular screw box or bush works the said screw box being conical externally the base
of the cone being towards the handle end of the tool. To the extreme end of the
stem the screw thread cutter or tap is attached, the acting end or point of the cutter
or tap being V shaped, square or of a figure the counterpart of that which it is
desired that the screw thread to be made shall have.
In using the new or improved tool or appliance described, part of the article to be
screw threaded or tapped is bored out to fit the conical screw box or bush on the
screw threaded portion of the stem of the tool. The article to be operated upon is
rotated in the chuck of a lathe and the tool with its screw box at the front or com-
mencing end of the screw is presented to the said article. When the screw box comes
in contact with the part of the article bored out to receive it, the said screw box rotates
with the said article and the workman holding the tool by its handle prevents its
rotation but permits it to advance in the line of its axis. The said tool with its cutter
or tap consequently advances into the rotating article at a rate proper to cut an
internal screw thread of the same pitch as the thread on the stem of the tool.
Although we have described the rotating of the screw box by connecting it directly
with the article under operation yet we wish it to be understood that the said article
may be connected to the screw box by a separate appliance rotating with the work in
the chuck.
The tool may also be modified and used in the manner hereinafter described.
Figure 1 of the accompanying drawing represents in perspective the new or
improved tool or appliance constituting the said invention;
Figure 2 represents the same partly in elevation and partly in section and
Figure 3 is an elevation of the front or cutter end of the said tool.
Figure 4 is a perspective view of the said tool with a modified screw cutter or
screw tap.
The same letters of reference indicate the same parts in the several figures of the
drawing.
"
a. is the stem of the said tool having at its outer end the wooden handle a' by
which the tool is held and advanced into the hollow article of clay or other soft
articles to be internally screw threaded or tapped.
At or about the middle of the stem a is the raised screw thread b on which is
situated the screw box c for the purpose hereinafter described, the said screw box
being preferably slightly conical externally. To the extreme end of the stem a the
screw cutter proper d is fixed by the screws e, e. The said cutter d has the
V shaped projection d' constituting the screw cutter or screw tap. The screw cutter
or screw tap has a radius greater than the internal diameter of the part of the

page_text: hollow article to be internally screw threaded and the said screw cutter or screw.
tap has a shape corresponding with the shape of the screw thread to be cut ;
that is to say, where a square threaded screw is to be formed in the hollow article
the said projection dis square instead of V shaped as represented.
The article to be internally screw threaded is provided with a conical mouth of
a size proper to fit the screw box c. The said hollow article is fixed in and rapidly
rotated by the chuck of a lathe. The tool or appliance is introduced axially into.
the article to be operated upon until the screw box c takes into the conical mouth
of the said article when the said screw box rotates with the said article and draws
the tool or cutter into the article at such a rate as to cause the cutter or tap d
to form a screw thread therein of a pitch similar to the pitch on the screwed
part b of the stem the handle a³ of the said screw cutter being held by the workman.
so as to prevent its rotation but permit of its advance into the article.
Where for any reason it is inconvenient or undesirable to shape the mouth of the
article to be operated upon so as to admit of the introduction of the tool therein
until the screw box fits the said mouth an intermediate tubular piece may be fitted
on the screw box so as virtually to form an extension thereof, the front end of which
intermediate tubular piece may be made so as to bear on the front end of the article.
under operation.
Instead of attaching a cutter d, d of the kind represented in Figures 1, 2 and 3.
to the stem a of the tool, a second screw thread may be formed on the extreme or
front end of the stem as represented in Figure 4 where the second screw or tapping
thread is marked f the said tapping thread having a longitudinal cut away part or
parts f crossing the thread.
Although we have described the carrying of the article under operation by the
rotating chuck of a lathe and the application thereto of a non-rotating tool yet we-
wish it to be understood that the said tool may be fixed in the chuck of a lathe, the
article under operation and the screw box on the screw of the tool being held
during the formation of the internal screw thread.
The new or improved tool or appliance constituting the invention hereinbefore-
described is especially useful for forming the internal screw threads in the hollow
stems of porcelain insulators for telegraph wires and the like but the said tool or
appliance may be used for forming screw threads in other hollow articles of clay or
other soft material such for example as the necks of bottles and the like.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that we claim
as the said invention ;-
The new or improved tool or appliance hereinbefore described and represented in
the accompanying drawing for cutting screw threads in hollow articles of clay or
other soft material, the said tool consisting essentially of a stem having at its front
end a screw cutter or screw tap and between the said screw cutter or tap and the rear-
end of the said stem, a screw thread of the same pitch as the internal screw to be
made in the hollow articles to be operated upon the said screw thread carrying a.
screw box which regulates the advance of the stem and its cutter into the articles,.
the said tool or appliance being used substantially as hereinbefore described.
Dated the First day of April 1896.
W. T. WHITEMAN,
Agent for the Applicants..