Improvements in Screw Drivers and like Tools,
Year: 1888

page_text: Improvements in Screw Drivers and like Tools,
We, FELIX CHANTRELL, machinist, of 613 Church Street, JAMES HERvey
STERNBERGH, and PHILIP HERVEY STERNBERGH, manufacturers, of 53, N. 4th Street,
all of Reading in the county of Berks, and State of Pennsylvania, United States of
America, do hereby declare the nature of our invention for IMPROVEMENTS IN SCREW
DRIVERS AND LIKE TOOLS 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 Drivers and like tools, and its main feature consists
It applies both
in the novel manner of connecting the shaft or bit with the handle.
to those tools in which the bit and handle are permanently connected and also to that
class in which the bit is readily thrown into or out of engagement with the handle.
The main object of the invention is, by a simple and effective construction, to cause
the strain brought upon the bit to be transmitted directly to the upper and commonly
heavier and stronger part of the handle. The invention also embraces an improved.
means of engaging the bit and handle in the last class of tools referred to.
In the accompanying drawings which illustrate this invention:-
Fig. 1, shows partially in section a screw driver in which the handle is thrown into
engagement with the bit by a pressure upon the end of the handle, the latter being
returned by a spring when the pressure is removed. The piece shown separately
above is to be secured in the opening of the handle to finish the tool.
Fig. 2, is a plan of the connecting bushing looking at the open end.
Fig. 3, shows, partially in section, a screw driver in which the handle and bit are
permanently connected, the closing piece or plug being shown separately as above, as
in Fig. 1.
Fig. 4, is a plan of the bushing or shank head which is secured to the end of the
bit as shown in Fig. 3.
Fig. 5, shows the shank end of a bit equivalent to that illustrated in Fig. 3, the
enlargement or head of the shank being in one piece with the bit and slight projections
being formed on the curved surface of the enlargement to serve the same purpose as
the ribs shown in Figs. 2 and 4.

page_text: .
The handle A, of wood or other suitable material is in one piece and may be of any
desired shape outwardly but the interior is hollow throughout, being bored to two
different sizes, with the larger bore A2 in the upper larger end. The shaft B is
preferably a round bar of steel of uniform diameter, except where shaped at the point
to suit the work for which it is to be used.
When it is intended that the handle shall be thrown into and out of engagement
with the shaft the form of construction shown in Fig. 1, may be used. A cap piece C,
a frustrum of a pyramid in shape, having a regular polygonal cross-section, is secured
to the shank end of the shaft B.
This may be accomplished by shrinking or forcing it on or in any other suitable
manner, or it may be forged solid if desired. A bushing D the curved outside
surface of which is grooved longitudinally as shown at D¹ or otherwise roughened for
the purpose, is forced into the large bore A² of the handle, the yielding material of the
latter conforming to said roughened or uneven surface and effectually preventing the
bushing from being turned in the handle. The hollow interior of the bushing is
shaped at the lower end to correspond with the cap piece C, having a series of flat
faces D² the same in number and size as those on the cap piece, so that when the
latter is pushed into the bushing said faces will coincide and the bushing cannot be
turned without rotating the cap piece and the shaft of which it is a part. The bushing
is sufficiently long to permit a spiral spring E to be placed between the top of the cap
piece and the shoulder D³ in the bushing.
In putting the parts together to construct the tool, the shaft B passes loosely
through the smaller bore until the cap-piece, which is secured to the shank as
described, rests upon the shoulder A' at the junction of the two bores. The bushing,
having the spring E within it, is then forced into the large bore until it is so close to
the cap piece that the latter can just be turned without engaging with it. This will
preferably bring the top of the bushing some distance below the top of the handle so
as to permit a plug F of the same material as the handle to be inserted in the opening
above the bushing and secured there by glueing or other means. This plug will
prevent the possibility of the bushing being pushed out by a strain upon the end of
the shaft, and when finished off flush with the top will give the handle both the
appearance and strength of a solid one, the glue serving to unite the plug and handle
so as to fully restore the strength lost by boring the latter.
The manner of operating the tool is evident from the construction. When the
point of the shaft is in contact with the work a slight longitudinal movement caused a
by the end pressure upon the handle will bring the bushing and cap piece into
engagement. The greater the number of flat faces employed the less will be the
longitudinal movement required to effect this. The shaft will then be rotated in either
direction with the handle until the end pressure is removed when the spring E will
release them and the handle may be returned without rotating the shaft.
When it is intended to simply unite the handle and shaft, substantially the same
means are employed as in the construction just described, the difference being that
the bushing is permanently connected to the shaft so as to form a shank head, instead of
being intermittently connected with it. Figs. 3 and 4 illustrate such a construction.
The bushing G the outside surface of which is equivalent to that shown in Fig. 2, 4
being provided with longitudinal ribs G³, is secured directly to the shaft B in the
same manner as the cap piece C in Fig. 1. The handle is bored to two sizes as before
described, and the body of the shaft B is passed through the smaller bore which it
may fit more tightly than in the previous construction, until the base of the bushing
is seated against the shoulder A₁, the plug F being subsequently secured in position.
The handle and shaft are thus positively united, and the torsional and end strains
upon the latter are transmitted to the handle through the bushing or shank
head G.
The modified form of shank end shown in Fig. 5, has a head H which is formed
solid instead of being a separate piece secured to it, and in place of the ribs (or
grooves D the curved surface has a number of small projections H' which are
represented as wedge shaped with the faces inclined inward and towards the point of

page_text: the shaft. These projections not only prevent the turning of the shaft in the handle
but also serve to prevent it from being forced out by the end pressure, the wedge
allowing them to readily enter but preventing withdrawal. It is therefore evident
that the plug F is not essential to retain the shaft in position and if desired it may be
dispensed with and the opening closed by other means.
The special manner of engaging the handle and the shaft shown in Fig. 1, and 2 is
much to be preferred to the serrations or teeth usually employed at the lower end of
the handle for this purpose, the engagement being effected by a reduced end movement
and without noise, and the amount of wearing surface in contact being very large.
It is not intended however to limit our invention to this connection, as its main
features, that is the single hollow handle and the bushing secured in the heart of it
and connected or united with the shaft-may be employed without using this preferred
connecting means.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
:
(1) A screw driver or similar tool consisting of a handle bored throughout its
length and a shaft or bit having its body passed through said bore and its shank end
connected with the handle by means of a bushing or shank head with uneven
surface secured in the bore in the larger end of the handle, substantially as
described.
(2) In the tool described a bit having a shank head secured in the larger end of
the handle substantially as set forth, the body of the bit extending through the
smaller end.
(3) In the tool described a bit having a shank end adapted to engage with a bushing
secured in the larger end of the handle substantially as set forth, and a spring E
arranged to throw them out of engagement.
(4) In the tool described a bit having a tapered head of regular polygonal cross-
section adapted to engage with a bushing secured in the handle, said bushing having
its interior shaped to correspond with the head, for the purpose specified.
Dated this 30th day of November 1888.