An Improved Stone-boring Tool.
Year: 1896

page_text: Date of Application, 18th Feb., 1896-Accepted, 28th Mar., 1896
An Improved Stone-boring Tool.
I, HERMANN SCHWARTZENHAUER, of 79 Steglitzerstrasse, Berlin, in the Empire
of Germany, Cabinet Maker, 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 a stone bore which may be used for boring in such a
manner that its cutting face performs a forward and backward turning movement,
whereas most of the bores heretofore known always make a turning movement in one
direction in the boring operation. The bore will be particularly suitable for boring
by hand, as a much smaller power requires to be exerted by the hand for performing
a forward and backward turning movement than a complete rotary movement.
This is due to the fact that in the forward and backward turning movement it is
not necessary to relinquish the tool, it will therefore be possible to always exert
an uniform pressure upon the stone.
In the accompanying drawing
Figure 1 represents a front view and ;
Figure 2 a side view of the bore.
Figure 3 shows a transverse section of the same.
In order to permit of an effective boring action in a forward and backward
turning movement, the cutting face b of the bore a is provided with teeth the
form of which is clearly shown in Figures 1 and 2. As illustrated in Figure 3, the
body of the bore is grooved semicircularly in transverse section, and its two cutting
edges are ground rather sharp.
The groove is designed for the reception of the dust produced by the boring, thus
obviating the jamming of the bore. The bore may with great advantage be used for
boring bricks, in order to avoid for instance the subsequent chiselling of holes in
walls. But according to the quality or hardness of its steel it may also be employed
for boring any other stone.
In the drawing a bore is shown for boring by hand, and is for this purpose
furnished with a handle g; of course it may also be used in an appropriate
machine which makes a forward and backward turning movement after the manner
of drills, when it will work with the same effectiveness.
A further advantage of the improved bore consists in that it will wear very much
less in the forward and backward turning movement than a bore which is always
turned in the same direction, inasmuch as in the bore forming the subject of the
said invention only one half of the cutting edge is always in operation, whereas
in the case of bores to which a rotary movement is imparted the whole cutting edge
of the bore works and will therefore wear more.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. A stone bore in which the boring takes place by a forward and backward
turning movement, the said bore being grooved in transverse section, and its front end

page_text: which converges to a point being provided with teeth, for the purpose of enabling
holes to be bored in stone.
Dated this 18th day of February 1896.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.