Improvements in Bits and other Boring Tools.
Year: 1897

page_text: This Print is in accordance with the Original Specification as it stands after
Amendment (under Section 11 of the Patents, &c. Act, 1883) as required by
the decision of the Law Officer of the 16th day of June 1898.
Date of Application, 7th Apr., 1897-Accepted, 13th Nov., 1897
COMPLETE SPECIFICATION (AMENDED).
Improvements in Bits and other Boring Tools.
I, MARTIN STEUDNER, of Gera-Debschwitz, in the Empire of Germany, Tool
Manufacturer, 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 bits and other boring tools and its object is to so.
construct them that they shall follow a straight course in boring and not be readily
deflected or diverted therefrom.
For this purpose the straight cutting edges at the end of the boring tool are
provided each with one or more recesses so that when such edges cut into the base
of the bore hole and turn therein, one or more circular ridges are formed or left
on the base of the bore hole corresponding to these recesses and having their
centres coinciding with the axis of boring.
In order that such recesses may be reproduced or maintained and not eliminated
by the ordinary method of grinding or re-sharpening such boring tool by grinding
its end faces, the recess is continued in the form of a groove, up the front face of
the tool which is rounded at the bottom by the cutting edge. Thus the recess
has not to be specially and independently reproduced every time the end face of
the tool is ground, but will be maintained by or during such grinding.
The invention is applicable in the same manner both to straight borers in which
the working face runs without twist longitudinally along the borer, and to twisted
or helical borers in which said working face twists helically around the axis of
the borer.
In the annexed drawing Fig. 1 shows a straight borer in longitudinal elevation
with a section showing the bore-hole. Fig. 2 is a plan of the bore hole. Fig. 3
is an elevation of a twisted or helical borer, and Fig. 4 is a plan view of the end
of either borer.
The cutting edges marked S1, S2, in Fig. 4 run nearly radially, while the outer
mantle faces of the borer D1, D2, are parts of a cylinder the axis of which is the
axis of the borer. The end faces E1, E2, of the borer are helical and the meeting
line of the end faces E¹, E2, with the front faces forms the aforesaid cutting
edges S¹, S².
It will be obvious therefore that if one or more grooves are made along the
front faces as shown at C1, C2, C3, C4 in Figs. 1, 3 and 4, these grooves will run
out at the end faces E1, E2, and form recesses in the cutting edges S1, S2, which,
when the borer is rotated will leave circular ridges such as K¹, K2 on the base
of the bore hole.
The groove C¹, or grooves C¹, C³, in the one front face are symmetrical with that C

page_text: or those C², C4 on the other so that the ridge left by the one cutting edge will not
be destroyed by the other cutting edge.
Such ridges K1, K2, centre the borer in the bore hole and tend to cause it to
follow a straight course.
It will be seen that to strengthen the borer which would be weakened by grooves,
such as C1, C2, C3, C4, and to provide for the greater strain on the outer parts
of the borer, the latter is made proportionally thicker towards the outer edge
(see Fig. 4).
By means of the straight cutting edges of this borer an equal cutting angle is
secured for all points of the surfaces to be worked. The hollow grooves which
cut the guiding combs on the base will have a cutting effect with their edges lying
obliquely to the bore direction, while the edges falling into the bore direction
serve for guiding. With a favourable cutting angle for the working straight
edges, the borer will be less shaken by the guiding combs and thus the work will
be facilitated and the working effect increased. The smaller shaking movement
of the borer, whilst it works, allows of using a weaker shaft and gives a smoother
bore hole.
Also in common bits the cutting edges can be provided with grooves for the
purpose of guiding.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I wish it to be understood that
I am aware of Thompson's Specification No. 3173 of 1895 and that I do not claim
anything described and claimed therein, but I declare that what I claim is:-
1. An improved borer having straight running cutting edges S¹ and S³, which
are provided with one or more hollows C1, C2, of any form, for the purpose of
cutting ridges K1, K2, on the base of the bore hole and of thus preventing the borer
from escaping.
2. A. borer having straight running cutting edges S¹, S³, provided with one or
more hollows C1, C2, and provided longitudinally on the side of the cutting edges
with one or more grooves for the purpose of obtaining always straight edges with
hollows by means of after grinding.
Dated this 7th day of Amil 1807
HERBERT HADDAN & Co.,
18, Buckingham, Street, Strand, London, w.C.,
Agents to Applicant.