Year: 1896

page_text: Taps
1, CHARLES ELTERICH, of 28 Sutton Place, New York, in the County of New
York and State of New York, in the United States of America, Machinist do
hereby declare the nature of this invention to be as follows:-
My invention has reference to improvements in implements, or devices, for cutting
threads, and it has for its object to provide an implement of this character adapted
for the purpose of cutting a perfect, continuous thread, and one which can be used
for a long time without appreciable wear.
To this end I construct the implement with a cutting thread of substantially
constant diameter at its bottom; the top of the thread being cut away at the entering
end and gradually increased in steps consisting of one or more teeth toward the
finishing end.
Heretofore, taps have been constructed with two or more threaded sections of
different diameters, each section having a uniform diameter throughout its length,
but in every instance, the diameter of the bottom of the thread increased with the
increased diameter of the apex of the thread; in other instances, the thread was not
continuous. Dies, as a rule, have heretofore been constructed with a thread of
substantially uniform diameter which was flared, or reduced, at the entering end.
In constructing the tap, a suitably turned rod is first cut with a parallel thread
extending from one end to the other. At the extreme end of the tap, the thread is
tapered for a short distance, the bottom of which taper thread extends within the line
defining the bottom of the thread. The thread is then reduced and cut taper at its
end, for the purpose of facilitating the entering of the tap and the cutting. A section
is then reduced cylindrical or straight; the next section is reduced to an abrupt taper;
the next section is reduced parallel and of greater diameter than the second preceding
section, and so on until finally the finishing thread section is reached, which latter is
left in its original condition. The bottom of the thread is, therefore, uniform through-
out with the exception of the extreme end of the tap where it is reduced for the
purpose above mentioned.
The finished tap, therefore, consists of a reduced end or point, a series of reduced
alternating straight and tapered portions, and a finishing portion. It is as usual
provided with flutes.
I have found that by having the thread continuous and of uniform diameter at its
bottom with the exception as to its point, as above stated, to facilitate entering, a
single tap will answer for the cutting of a perfect thread of any desired length,
without appreciable wear on the tap. By forming the thread continuous, great
strength and resisting power, a matter very essential in taps, is obtained.
In practice, I make the taper portions between the cylindrical or straight portions
quite abrupt.
One of the important features of the present construction for taps is that the thread
is finished smooth and solid, without break or tear, in view of the fact that the
successive taper and straight portion will equalize and smooth the thread, even if the
tap should tear on entering.

page_text: In constructing the die, I proceed as follows:-
Into a suitably formed steel blank is drilled and reamed a hole having stepped
portions. This hole is tapped out with a suitable tap, and the thread produced has a
substantially uniform diameter at its bottom, while its inner diameter is stepped. One
end portion of the thread represents the finishing portion of the die, and, in this
portion, the thread is of the full standard size. The portion of the thread at the
opposite end represents the entering portion of the thread, and, in this portion,
the top of the thread is cut away, or reduced, and the hole thereby made larger.
The next portion is also reduced at its top, but the diameter at the top of these teeth
is smaller than that of the top of the teeth at the entering portion.
The die, as described, therefore, consists of a series of gradually increasing portions,
so that the material acted upon is gradually cut away up to the finishing portion,
while the successive portions always cut outwardly from the base line of the thread.
If desired, intermediate taper portions may be introduced to facilitate the cutting.
In practice, I remove a portion of the die at the entering end of the same to
facilitate entering, while a like removal may be made at the finishing end to enable
the die to be reversed for the usual purpose. To provide for clearance, I first back
off the teeth with a suitable cutter and then file down the forward portion to obtain
the proper shape.
With the present construction of die, I obtain a perfect thread, which is smooth
and solid and is not expanded or stretched bodily. The thread not being stretched
by the die, it possesses the full strength of the material. All the known dies produce
more or less stretching of the threads and the pitch is thereby increased from the
standard. Furthermore, in my present construction, the diameter of the shank at the
terminal threads is gradually increased, thereby producing bolts of extraordinary
strength at the usual weak point.
The cutting action of a die embodying my invention may be described as quite
similar to the action of the thread cutting tool in a lathe in making a succession
of cuts.
While I have herein stated that the base line of the threads must be substantially
uniform in diameter, I do not wish to be understood that the said base line cannot be
slightly taper.
It is, of course, to be understood, that in adapting the invention to dies for cutting
threads on pipes, where a taper thread is usually formed, the base line of the thread
must have a constant taper corresponding to that of the stepped cutting line.
Dated May 5th 1896.
HARRIS & MILLS,
23 Southampton Buildings, London, W.C., Agents.
Improvements in Taps and Dies.
I, CHARLES ELTERICH, of 28 Sutton Place New York in the County of New
York and State of New York in the United States of America, Machinist, 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 :-
My invention has reference to improvements in implements or devices, for
cutting threads and it has for its object to provide an implement of this character
adapted for the purpose of cutting a perfect, continuous thread, and one which
can be used for a long time without appreciable wear.
To this end I construct the implement with a cutting thread of substantially

page_text: Fig. 6 is a diagrammatic view illustrating the construction of the cutting thread.
Figures 7, 8 and 9 are detail views illustrating the manner of constructing clearance
for the cutting thread.
Fig. 10 is a central cross section showing the shape of the orifice in the die before
forming the thread.
Similar letters of reference designate corresponding parts throughout the several
views of the drawings.
Referring at present to Fig. 1, I shall proceed to describe the manner of
construction of the tap, which is as follows:-
A suitably turned steel rod is first cut with a parallel thread extending from one
end to the other. At the extreme end of the tap, the thread is tapered for a short
distance as at a¹ between lines 1 and 2, the bottom of which taper thread extends
within the line 9 defining the bottom of the thread a. The thread is then reduced
and cut taper between the lines 1-2 and 2-3 for the purpose of facilitating the
entering of the tap and the cutting. The section 3-4 is then reduced cylindrical or
straight; the section 4-5 is reduced to an abrupt taper; section 5-6 is reduced
parallel and of greater diameter than section 2-4, and so on until finally the finishing
thread section 7-8 is reached, which latter is left in its original condition. The
bottom of the thread is, therefore, uniform throughout with the exception of the
extreme end of the tap where it is reduced for the purpose above mentioned.
The finished tap, therefore, consists of a reduced end or point, a series of reduced
alternating straight and tapered portions b. c and a finishing portion b. It is as usual,
provided with flutes d.
I have found that by having the thread continuous and of uniform diameter at its
bottom with the exception as to its point, as above stated, to facilitate entering, a
single tap will answer for the cutting of a perfect thread of any desired length,
without appreciable wear on the tap. By forming the thread continuous, great
strength and resisting power, a matter very essential in taps, is obtained.
In practice I make the taper portions c between the cylindrical or straight portions 6
quite abrupt.
One of the important features of the present construction for taps is that the thread
is finished smooth and solid, without break or tear, in view of the fact that the
successive taper and straight portion will equalize and smooth the thread, even if the
tap should tear on entering.
Referring at present to Figures 6 and 10 of the drawings, I shall now proceed to
describe the manner of constructing the die, which is as follows:-
Into a suitably formed steel blank D is drilled and reamed a hole having
the stepped portions 1, 2 and 3. This hole is tapped out with a suitable tap,
and the thread produced is then in the form shown in Fig. 6, it having a substantially

page_text: uniform diameter d at its bottom, while its inner diameter is stepped. The portion of
the thread between the lines 5-5 and 6-6 represents the finishing portion of the die,
and, in this portion, the thread is of the full standard size. The portion of the thread
between the lines 7-7 and 8-8 represents the entering portion of the thread, and,
in this portion, the top of the thread is cut away, or reduced, and the hole thereby
made larger. The interinediate portion, that is, the portion between the lines 6-6
and 7-7, is also reduced at its top, but the diameter at the top of these teeth is
smaller than that of the top of the teeth between the lines 7-7 and 8-8.
The die, as described, therefore, consists of a series of gradually increasing
portions e fandy so that the material acted upon is gradually cut away up to the
finishing portion g while the successive portions always cut outwardly from the base
line of the thread. If desired, interniediate taper portions, as e, f, as indicated by
dotted lines in Fig. 6, may be introduced to facilitate the cutting.
In practice, I remove a portion of the die at the entering end of the same, as shown
in Figures 4 and 5, to facilitate entering, while a like removal may be made at the
finishing end to enable the die to be reversed for the usual purpose. To provide for
clearance, I first back off the teeth, as at j with a suitable cutter, as shown in
Figures 7 and 8, and then file down the portion to obtain the shape shown in
Fig. 9.
With the present construction of die, 1 obtain a perfect thread, which is smooth
and solid and is not expanded or stretched bodily. The thread not being stretched
by the die, it possesses the full strength of the material. All the known dies produce
more or less stretching of the threads and the pitch is thereby increased from the
standard. Furthermore, in my present construction, the diameter of the shank at the
terminal threads is gradually increased, thereby producing bolts of extraordinary
strength at the usual weak point.
The cutting action of a die embodying my invention may be described as quite
similar to the action of the thread cutting tool in a lathe in making a succession
of cuts.
While I have herein stated that the base line of the threads must be substantially
uniform in diameter, I do not wish to be understood that the said base line cannot be
slightly taper.
It is of course to be understood, that in adapting the invention to dies for cutting
threads on pipes, where a taper thread is usually formed, the base line of the
thread must have a constant taper corresponding to that of the stepped cutting line.
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 I
claim is.
1. A thread cutting implement provided with a cutting thread of substantially
constant diameter at its base line; the top of the thread being cut away at the
entering end and gradually increased by steps toward the finishing end, substantially
as described.
2. A tap constructed with a thread composed of alternating straight and taper
sections of constant diameter at its bottom; the top of the thread being reduced at
the entering end of the tap and gradually increasing in diameter toward the finishing
end, substantially as described.
3. A die provided with a thread of substantially constant diameter at its base line
having its top cut away at the entering end, but leaving the full width of the thread
at the base line; said thread being gradually increased towards its apex by steps
consisting of one or more teeth, substantially as described.
4. A die provided with a thread of substantially constant diameter at its base line,
and having its top cut away at the entering end and gradually increased by steps of
one or more teeth, and the backs of the teeth cleared circumferentially backward
and tapered from the clearance portion to the cutting edge, substantially as
described.
5. A die provided with a cutting thread of constant taper at its base line; the

page_text: top of the thread being cut away at the entering end and gradually increased by steps
consisting of one or more teeth to the finishing end, substantially as described.
ated a 5th 1007
HARRIS & MILLS,
23 Southampton Buildings, London, W.C, Agent..
HARRIS & MILLS,
23 Southampton Buildings, London, W.C, Agent.