An Improved Appliance for use in Polishing Screws and the like.
Year: 1891

page_text: Date of Application, 24th Dec., 1891-Accepted, 20th Feb., 1892
COMPLETE SPECIFICATION.
An Improved Appliance for use in Polishing Screws and the like.
I, GEORGE FREDERICK REDFERN, of the firm of G. F. Redfern & Co., The
General Patent Office, No. 4, South Street, Finsbury, in the County of London,
Patent Agents, do hereby declare the nature of this invention (a communication
to me by Johannes Krimmel and Ludwig Boss, of Ebingen, Wurtemburg, in the
Empire of Germany, Manufacturers), 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 machinery for polishing screws, such as is chiefly used
by watchmakers, in order to effect the polishing of small screws before use.
The machines for polishing screws heretofore used for this purpose have consisted
of a spindle fixed in a detachable frame, and provided with a gripping arrangement
to hold tightly the screw to be polished.
To set this machine in action the left hand is placed on the spindle, which is made
polygonal in section, and the latter then has a to and fro motion imparted to it by
backward and forward movements of the hand. As the result of this to and fro
motion of the hand however, the disadvantage arises that the worker cannot keep
the upper portion of the body steady, and thus an unfavourable influence is exerted
on the polish secured, since under these circumstances the fine strokes or markings
of the polish cannot be made to radiate exactly from the central point of the
screw
The chief object of the above mentioned invention is to do away with this
disadvantage, and it is characterized by the fact that the spindle is set in rotatory
motion by a wheel and belt, the connection of the grooved pulley with the handle
being effected by an elastic coupling.
A further novelty in this machine consists in an improvement in the gripping
machine for holding the screw.
In the accompanying drawing :-
:-
Figure 1 shews the new polishing machine in longitudinal section.
Figures 2 and 3 shew the two end elevations of the machine.
Figures 4 to 6 are views of details.
In the supporting frame A of the machine which is provided on its under side
with lugs a so that it can be easily fixed in the vice, the polishing spindle B and
the centering screw C are carried."
The centering screw C works through the upright c of the framing and carries
on the inner side of the upright the loose grooved pulley D, which is prevented
from lateral movement by the screw nut d. A belt or gut band (Figure 3) passes
from the lesser grooved pulley D to the larger grooved pulley F which runs in a
bearing in the downwardly projecting arm a¹ of the bed-plate, and can be set in
motion by the crank handle G.
As the apparatus is only intended for occasional work and is at such times
intended to be screwed into a vice, it is not advisable to employ a larger or heavier
fly wheel to control the rotatory movement. Nevertheless it is necessary to render
the movement of the large grooved pulley so equable that the workman may not be
subjected to disturbing jerks when the tool in working touches the harder portions
of the material under treatment. In order to render this equalizing of the motion
possible without the use of the fly wheel by which this object has hitherto been
attained the handle and grooved pulley F are united by an elastic connection, that
is to say, the grooved pulley F and the handle are both loose upon the axis of
revolution and the connection of the two is effected by means of a spiral spring g
which lies flat in a space turned out of the grooved pulley F and is secured by its
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page_text: 9
inner end to this pulley and by its outer end to the crank handle G. If the
handle G be turned the spring g is put into such a state of tension that the friction
of the bearings is overcome, and then the revolution of the grooved pulley F
follows the turning of the handle and sets in rotation the small grooved pulley D
which by means of its tenon d¹ transmits this rotation to the polishing spindle B.
If now a screw be clamped in this spindle and polished, the work proceeds equably
as long as the tool affects only equally hard spots of the material, as soon however.
as the tool encounters a harder portion of the material the force required to rotate
the polishing spindle becomes greater, and the workman would experience a jerk
which would interfere with the steady turning of the crank handle if the connection
of the handle with the grooved pulley were not effected in this new and peculiar
manner. When the tool encounters a harder place, the turning of the grooved
pulley is in fact interfered with, but in spite of this the revolution of the handle
goes on steadily and gives rise to further tension of the spring g until the gradual
increase of the working force has reached such a point that the resistance of the
hard place is likewise overcome.
The workman does as a matter of fact increase the force expended in rotating
the crank handle but as this increase takes place gradually and without the
workman being conscious of it, the harder places in the material exercise no
disturbing influence upon either the workman or the work.
Still more forcibly apparent than in polishing does the advantage of the new
and improved arrangement become when a drill is inserted into the polishing
spindle B and the machine is used for boring a hole.
Every practical man knows the difficulties to which the hard places occurring in
the metal give rise in boring a hole with a tool without a fly wheel, and how easily
such hard places, giving rise to a jerk, cause fracture of the drill.
With the new elastic connection between the handle and the grooved pulley
however, this sudden jerk is quite got rid of, and the power is increased not
suddenly but gradually so that the increased resistance is easily and smoothly
overcome.
:
A further improvement relates to the clamping of the object which is being dealt
with to the spindle B. In the drilled out front end of the spindle is inserted the
loose tube H (shewn detached in elevation and section at Figure 5) in such a way
that it can revolve freely without movement in a longitudinal direction. This loose
tube is similarly drilled out and its mouth countersunk in the usual way, and
receives the actual clamping tube h (shewn in elevation and in longitudinal and
transverse sections at Figure 6) the head of which is conically formed to correspond
with the mouth of the loose tube H and which is slotted at its upper part so that
the screw to be polished can be inserted into the hollow of the clamping tube.
The inner end of the clamping tube is provided with a screw-thread, and can be
screwed into a corresponding threaded recess at the bottom of the recess in the
spindle B. This screwing in of the clamping tube, and the simultaneous compression
of its head are effected by turning the loose tube H which with this object is
provided with a projecting milling, Figure 5. In order to transmit the rotation
of this loose tube a pin I, Figure 1, projecting inwards is secured to it, which
corresponds with a groove i, Figure 6, in the inner end of the clamping tube.
setting up the apparatus the clamping tube h is so inserted into the loose tube that
the pin I lies in the groove in the clamping tube h. If now the loose tube H be
turned it carries the clamping tube with it in this rotation, and since when the
clamping tube is properly inserted it is screwed at the same time more or less into
the screw-threaded recess in the fixed spindle B, it retreats farther and farther into
the loose tube H and at last lies with its conical head in the conical recess in the
latter so that by this means a firm compression of the slotted head is effected, which
head, in turn, firmly holds the inserted object or tool. Since the possible approximation
of the sides of the slotted head is of course limited, it is advantageous to use, for
very small screws, a smaller clamping tube K (shewn in elevation and longitudinal
and transverse sections at Figure 4) which is also slotted, sprung, and provided
In

page_text: with a recess which corresponds with screws of the smaller kind. This clamping
tube K is simply thrust into the recess of the clamping tube H after the work has
been placed in it, and then held tight by the clamping tube.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In machinery for polishing screws and the like without fly-wheels, the
arrangement of cord and pulley gear, in which the crank-handle is so united by an
elastic connection, to the larger grooved pulley that the crank-handle and larger
pulley are situated loosely upon the axis of rotation, and connected by a spiral-
spring, the inner end of which is secured to the large pulley and the outer end to
the crank-handle, so that when the crank-handle is turned the spiral-spring is
thrown into tension by the resistance which the working spindle offers to the
rotatory movement, before the handle sets the cord and pulley gear in motion,
with the object of equalizing gradually by the elastic connection between the
crank-handle and the cord and pulley gear, variations of the force required in
working, and thus preventing the imparting of jerks to the workman or the
work, substantially as hereinbefore described.
2. In a machine such as is claimed in the preceding claiming clause the
employment of a gripping arrangement for the object or the tool, which consists
of a loose tube which fits into a recess in the working spindle, can rotate freely in
it without longitudinal shifting and receives a vertically inserted clamping tube
which, during the turning of the loose tube, screws into a corresponding
screw-threaded recess in the bottom of the recess in the working spindle by means
of the screwed portion provided at its own end, thereby holding the object or the
tool firmly, substantially as hereinbefore described.
3. The improved appliance for use in polishing screws and the like hereinbefore
described and illustrated in the accompanying drawing.
Dated the 24th day of December 1891.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.