Year: 1886

page_text: Date of Application, 9th June, 1886.
Complete Left, 6th Apr., 1887.
Complete Accepted, 6th May, 1887
I, CHARLES TENNETT, of East Street, Bradford, in the County of York, Engineer
do hereby declare the nature of the said invention to be as follows:-
This invention relates to improvements in that class of drills in which the parallel
sides of the drill have cutting edges.
To carry out my invention I form my drill with three equal and similar wings or
webs which are parallel with the axis of the drill and stand off from the centre line of
the drill either in true radial lines or in lines leading slightly forward in the direction
in which the drill rotates.
The wings are equidistant from one another and consequently are placed at equal
angles to one another.
The cutting point of the drills is ground to the usual form and the cutting edges of
the sides or wings of the drill are ground perfectly flat upon an ordinary grindstone
or emery wheel.
Hitherto drills have frequently been twisted after the grooves have been rolled,
planed, or cut, out of solid round bars, but in forming drills according to my
improvements the bars of steel may in the first instance be rolled, drawn, stamped or
cast in Tor Y section, and then planed or otherwise finished or ground to the
required shape, and they remain in a straight form no twist being given to them.
Dated this Eighth day of June 1886.
D
WM. JAS. BAKER,
Town Hall Chambers, Bradford,
Agent for the Applicant.

page_text: CHARLES TENNETT of East Street Bradford in the County of York Engineer
hereby declare the nature of this invention and in what manner the same is to
performed, to be particularly described and ascertained in and by the following
ement:
sules of the drill have cutting edges.
To carry out my invention I form my drill with three equal and similar wings or
webs which are parallel with the axis of the drill and stand off from the centre line of
the drill either in true radial lines or in lines leading slightly forward in the direction
in which the drill rotates.
The wings are equidistant from one another and consequently are placed at equal
angles to one another.
The cutting points of the drills are ground to the usual form and the cutting edges
of the sides or wings of the drill are ground perfectly straight and parallel with the
axis of the drill upon an ordinary grindstone or emery wheel.
Hitherto drills have frequently been twisted after the grooves have been rolled,
planed, or cut, out of solid round bars, but in forming drills according to my
improvements the bars of steel may in the first instance be rolled drawn, stamped
or cast in Tor Y section, and then planed or otherwise finished or ground to the
required shape and they remain in a straight form no twist being given to them.
In order to enable my invention to be fully understood I will proceed to describe
the same with reference to the accompanying drawings in which
Figure 1, represents a plan, and Figure 2 a section of the bar of steel of which my
improved drill is formed.
Figure 3 represents an elevation of the drill as it is pointed for boring iron, and
Figure an elevation of a drill with a square termination which produces a flat
bottom to a hole that has been drilled, and this form is also employed as a traversing
drill to operate in a lateral direction for the purpose of cutting key seats in shafts, for
cotter-holes or the like.
In Figure 1 the segment F indicates a part of the circle formed by the revolution
of the outer edges of the drill. E is a segment of an imaginary circle forming the

page_text: centre or body of the drill, and the tangent line C, D touching this circle indicates
one of the lines of the wing, and the radial line A. B the other line of the wing, at the
outer angle of which wing is the cutting edge of the drill.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is
The improved construction of drill for metals, the steel for which drill is rolled in
bars, having three wings of the form described and represented in Figure 1, each
wing having a straight cutting edge.