Improvements in or relating to Drilling or Boring Tools.
Year: 1895

page_text: Date of Application, 13th Feb., 1895
Complete Specification Left, 2nd Oct., 1895-Accepted, 30th Nov.. 1895
Improvements in or relating to Drilling or Boring Tools.
A communication by THEODOR WESSELMANN, of 11, Schwerinstrasse, Berlin, in
the Empire of Germany, Machine Builder.
1, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of The Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool and 6, Bank Street,
Manchester, both in the County of Lancaster, 118, New Street Birmingham in
the County of Warwick and 31, High Holborn in the County of Middlesex, Civil
Engineer do hereby declare the nature of this invention to be as follows:-
:-
This invention has for its object a bar from which by simply grinding, a double
borer or drill may be made, the central or inner cutting edges of which act as a
front borer or borer point, whilst the two larger outer edges act as after-borers.
The object of this arrangement is to allow in the boring of large holes of a small
hole being first directly made and of the after boring out or reaming to a greater
width being effected simultaneously by the same borer in a similar way to that of a
centre bit, and also to permit of boring with great peripheral speed. By this means
it is possible to attain with this double borer a very energetic and increased boring
action. The central borer point cuts without reaming a small central hole as shown
in Figure 5, whilst the outer edges or cutters have an increased cutting speed at all
their points. By means of such double borers very thick cuttings may be obtained
without causing the borer to become heated.
The essential features of this double borer consist in :—
a. The combination of a borer and reamer or preliminary and after-borer in a
single tool which is to he made from a straight rolled bar which is formed with two
projecting ridges.
b. The making of both cutting edges of the preliminary and after-borer simul-
taneously by simply grinding.
c. The selection of the section of the borer bar in such a way that when the
borer is ground the cutting edges of the same are made in the usual manner by the
formation of two ground surfaces inclined towards one another, whilst in conse-
quence of the ridges on the bar special cutting edges result both for the front as
well as the after-borer, but these cutting edges lie at different angles. The ground
surfaces may also as in ordinary borers be level or have a spiral surface by suitably
turning the borer bar when grinding.
By employing more than two ridges more than four cutting edges may be
formed.
In the accompanying drawings: :-
Figure 1 shows in elevation a straight borer bar with ground cutting edges and
two ridges;
Figure 2 is a side elevation of the same;
Figure 3 is a plan view of Figure 1 or Figure 2;
Figure 4 is a cross section of the borer bar;
Figure 5 is a section of a hole made with one of these double borers;
Figure 6 shows in elevation a straight borer bar with four ridges;
Figure 7 is a plan of Figure 6;
Figure 8 shows in elevation a spirally twisted borer bar with two ridges ;

page_text: •
The shape of the section of the borer bar will now be explained.
The cross section shown in Figure 4 of the borer bar forms generally a rect-
angular figure, the two narrow sides of which are curved to correspond to the circle
of the hole to be bored. The two wide sides are so formed that in the centre of
the section the metal bar is thinner than at the circumference of the cross section
in the circle coinciding with the periphery of the whole.
By this centrally reduced thickness of the borer bar, the cuttings resulting from
boring within the bore hole formed may be easily removed.
At the points d d of the cross section lie the cutting edges of the borer bar
aud the end cutting edges dcb are curved sickle shaped in order to bring the
separate points of the cutting edges to the attack when cutting. The parts at a
lying opposite to the cutting edges dc b of the borer bar, as seen in the cross
section, are however not curved, but run practically radially to the centre of the
section.
Two projections on the wide sides-d e a thus-appear with sharp bevelled points in
proximity to the centre of the section obliquely opposite to one another, which
projections form the sharp edged ridges visible on the sides of the borer bar.
These ridges form at 6 the projecting and peculiar shaped cutting edges of the
second central or inner front borer which thereby obtains cutting surfaces entirely
separated from the outer after-borer.
e
If on the borer bar of this particular section there be then ground in the
usual manner, as shown in Figures 1 and 2, at a given angle, two surfaces cutting
one another in the final edge è e of the whole borer but otherwise entirely equal,
the hollow cc of the sides forms the cutter for the after-borer, whilst the hollow
at forms the peculiarly shaped cutter for the front borer. The cutting edges of
the front borer extending from 6 to b have however a more obtuse angle to the
longitudinal axis of the borer bar than the cutters cc of the after-borer, which is
very favourable for the front borer as with the same pressure it has an equal
penetration to the after-borer.
In spite of the common character of the ground surfaces, the cutters 6b of the
front borer, as shown in Figure 3, lie in a radial direction opposed to the cutters.d d
of the after-borer at a greater angle according as the projection of the bevelled
longitudinal ridge at 6 from the sides of the borer is made larger or smaller. If
the straight borer rod be twisted spirally on its longitudinal axis before being
ground, as shown in Figure 8, a so-called "American" borer results, in which by
simply grinding quite in the same manner as hereinbefore described, two pairs of
cutters may also be formed, one pair for the after-borer and the central or inner
pair for the front burer. Thus from such American borers a double borer results at
one grinding.
It more than two ridge projections or bar ridges be selected, the cutting edges b-d
are repeated.
Dated this 12th day of February 1895
COMPLETE SPECIFICATION:
Improvements in or relating to Drilling or Boring Tools.
A communication by THEODOR WESSELMANN, of 11 Schwerinstrasse, Berlin,-in
the Empire of Germany, Machine Builder.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6, Bank Street,
Manchester, both in the County of Lancaster, 118 New Street, Birmingham in 'the
County of Warwick and 31 High Holborn in the County of Middlesex, "Civil
.

page_text: projections form the sharp edged ridges visible on the sides of the borer_bar.
These ridges form at b the projecting and peculiarly shaped cutting edges of the
second central or inner front borer which thereby obtains cutting surfaces entirely
separated from the outer after-borer.
If on the borer bar of this particular section there be then ground in the usual
manuer, as shown in Figures 1 and 2, at a given angle, two surfaces cutting one
another in the final edge e e of the whole borer but otherwise entirely equal, the
hollows c of the sides form the cutter for the after-borer, whilst the hollows at b
form the peculiarly shaped cutter for the front borer. The cutting edges of the
front borer extending from 6 to 6 have however a more obtuse angle to the
longitudinal axis of the borer bar than the cutters c c of the after-borer, which is
very favourable for the front borer as with the same pressure it has an equal
penetration of the after-borer.
In spite of the common character of the ground surfaces, the cutters 66 of the
front borer, as shown in Figure 3, lie relative to the cutters d d of the after-borer
at a greater radial angle according as the projection of the bevelled longitudinal
ridge at 6 from the sides of the borer is made larger or smaller. If the straight
borer rod be twisted spirally on its longitudinal axis before being ground, as shown
in Figure 8, a so-called "American borer results, in which by simply grinding
quite in the same manner as herein before described, two pairs of cutters may also
be formed, one pair for the after-borer and the central or inner pair for the
front borer. Thus from such American borers a double borer results at one
grinding.
If more than two ridge projections or bar ridges be selected, the cutting
edges b―d are repeated.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
.my foreign correspondent, I declare that what I claim is―
1. A straight borer bar of an angular and uniform cross section formed with two
sharp edged longitudinal ridges (6 b) on opposite sides to one another on the edge
lines of the cross section in such a manner that when the borer bar is ground with
two oppositely inclined faces a double borer with two pairs of separate cutting
edges is produced, substantially as described.
2. A spirally twisted borer bar formed from a borer bar, provided with sharp-
edged longitudinal ridges such as described in such a manner that when ground
with two oppositely inclined faces a double borer with two pairs of separate cutting
edges is produced, substantially as described.
3. Bars formed with any desired or suitable number of sharp edged longitudinal
ridges on opposite sides.in such a manner that drilling or boring tools with any
desired number of cutting edges in pairs may be produced by grinding two
- oppositely inclined faces on said.bars, substantially as set forth.
Dated this 1st day of October 1895.