IMPROVEMENTS IN BORING TOOLS
Year: 1869

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, Patent Agent, for the Invention of
"IMPROVEMENTS IN BORING TOOLS."-A communication from abroad by
Alexander Allan, of the City, County, and State of New York,
United States of America.
Sealed the 29th March 1870, and dated the 5th November 1869.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition,
on the 5th November 1869.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County
of Middlesex, Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN BORING TOOLS," to be as follows:-
This Invention relates to improvements in tools for boring square or
nearly square or other angular holes in wood, sheet metal, or other sub-
stance, and consists of a tool representing in cross section an equilateral
triangle provided with a pyramidal point coinciding with the centre of

page_text: the triangle, and connected in the stock so as to have lateral play when
the stock is such as not to have such movement as in a lathe mandril
or power drill stock; but when used in a hand brace or stock the lateral
play therewith is not necessary.
The Invention also consists in the combination with the aforesaid tool
of guides with square or other angular holes to regulate and control the
lateral movement of the tool which works through the holes, the said
guides to be used when it is desirable to control the angles of the holes
to be bored, as when used without the said guides the angles are liable
to be established irregularly in relation to the sides or cross section of
the article in which the holes are formed.
Figure 1 of the Drawing is a perspectve view of the tool; Figure 2 is
a vertical section of the same; Figures 3, 4, 5, 6, and 7 are diagrams
illustrating the theory of the operation of the tool; and Figure 8 is a
top view of the tool guide and its ring. Similar letters of reference
indicate corresponding parts in the several Figures.
In the arrangement illustrated for use by hand the tool is supported
on a firm base A, to which is attached the clamping box B by means of
the straps C, C. Inside of box B is the clamp D which holds the work, and
which is adjusted by the screws 8, 8. From the top of the box B rises the
hollow standard E, which is screwed into a recess in B, as shown in
Figure 2. Below the standard E is inserted a ring F, which turns in the
recess which receives it, and is held in any desired position by the set
screw 8¹. In the middle of this ring is the square guide G, Figures 2
and 8. This guide receives the triangular cutting tool H, which turns
in it while performing its work. The tool H is inserted in a tool stock I
threaded at its upper end, and working loosely in a female screw in the
upper end of the standard E.
A small amount of play of the tool stock
is essential to the proper operation of the tool, but a slight excess of play
is not detrimental. A handle K attached to the top of the tool stock I
serves to operate the tool. The operation is as follows:-The article to
be bored is inserted in the clamp box B and held by the clamp D.
adjusted by the screws 8, 8. The guide G is adjusted to its proper
relative position to the work by turning the ring F and holding it by the
set screw 8. By means of the handle K the tool H is caused to descend
till it passes into the hole in the base A through the article subjected to
its action. The hole produced will be square and correspond in size with
the opening in the guide G. The hole may be characterized by a slight

page_text: rounding in the corners. The cross section of the tool H is an equi-
lateral triangle, whose sides correspond in length with the sides of the
square opening in the guide G. The point of the tool is pyramidal, the
apex being the centre of the triangle forming its cross section. When
the tool is used in a lathe or power drill the guide may be held in any
approved way, and the stock E may be dispensed with, the lathe or
drill stock taking its place, and the feeding being effected by the lathe or
drill appliances. In these cases also the work may be held in any other
way. The rationale of the operation will be explained by reference to
the diagrams Figures 3, 4, 5, 6, and 7.
In these diagrams a, b, c, is
an equilateral triangle representing the cross section of the tool H,
d marking the point of the tool. In Figure 7 the triangle is shown in
the middle of a square e, f, g, h, representing the square opening
in the guide G. The line i, f, in this Figure shows the amount of play
necessary to the proper operation of the tool in a guide of this size.
In Figures 3, 4, 5, and 6, the triangles a, b, c, represent the four
positions of the tool in relation to the square opening in the guide G
assumed during one revolution. The action appears to be as follows:-
When the point d of the tool encounters the surface of the wood or
metal to be bored it meets with sufficient resistance to thrust it to one
side until one of the angles of the tool is driven into one of the angles
of the guide; it then occupies, let us suppose, the position represented
in Figure 3. In that position the angle c becomes a centre of rotation,
and the angle 6 describes the arc b, f; this brings the tool into the
position represented in Figure 4; here the point b becomes a centre,
and the point a describes the arc a, f; this brings the tool into the
position represented in Figure 5, where the point a becomes a centre,
and the point c describes the arc c, f. The tool is now in the position
shown in Figure 6, point c becoming a centre, and the point b
describing arc b, c. This last movement brings the tool into its initial
position in relation to the guide, with the exception that the side b, c,
of the tool is in contact with the left side of the guide opening instead
of the side a, c, as in Figure 3. By changing the form of the guide
angular holes of other forms than square may be bored on the same
principle of operation. Practice will enable a skilful workman to use
the tool without a guide in an ordinary brace, giving the requisite
eccentricity or play to the tool by his judgment alone. The guide
supplies the place of this skill to inexperienced hands.

page_text: For boring in soft wood I propose to notch or groove the cutting edges
with spiral or gimlet-pointed grooves, which besides cutting faster
serve to feed or draw the tool into the wood.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alexander Melville Clark in the Great Seal Patent
Office on the 29th April 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of November, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alexander Melville Clark, Her special
licence that I, the said Alexander Melville Clark, my executors, adminis-
trators, and assigns, or such others as I, the said Alexander Melville
Clark, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN BORING TOOLS," a communication to me from abroad by
Alexander Allan, of the City, County, and State of New York, United
States of America, upon the condition (amongst others) that I, the said
Alexander Melville Clark, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Alexander Melville Clark, do hereby
declare the nature of the said Invention, and in what manner the same
is to performed, to be particularly described and ascertained in and
by the following statement, reference being had to the Sheet of Drawings

page_text: hereunto annexed, and to the letters and figures marked thereon (that
is to say) :-
This Invention relates to improvements in tools for boring square or
nearly square or other angular holes in wood, sheet metal, or other sub-
stance, and consists of a tool representing in cross section an equilateral
triangle provided with a pyramidal point coinciding with the centre of
the triangle, and connected in the stock so as to have lateral play when
the stock is such as not to have such movement as in a lathe, mandril,
or power drill stock; but when used in a hand brace or stock the lateral
play therewith is not necessary.
The Invention also consists in the combination with the aforesaid tool
of guides with square or other angular holes to regulate and control the
lateral movement of the tool which works through the holes, the said
guides to be used when it is desirable to control the angles of the holes
to be bored, as when used without the said guides the angles are liable
to be established irregularly in relation to the sides or cross section of
the article in which the holes are formed

page_text: top of the tool stock I serves to operate the tool. The operation is as
follows:-The article to be bored is inserted in the clamp box B and held
by the clamp D adjusted by the screws 8, 8. The guide G is adjusted
to its proper relative position to the work by turning the ring F and
holding it by the set screw 81. By means of the handle K the tool H is
caused to descend till it passes into the hole in the base A through the
article subjected to its action. The hole produced will be square and
correspond in size with the opening in the guide G. The hole may be
characterized by a slight rounding in the corners. The cross section of
the tool H is an equilateral triangle, whose sides correspond in length
with the sides of the square opening in the guide G. The point of the
tool is pyramidal, the apex being the centre of the triangle forming its
cross section.
When the tool is used in a lathe or power drill the guide may be held
in any approved way, and the stock E may be dispensed with, the lathe
or drill stock taking its place, and the feeding being effected by the lathe
or drill appliances. In these cases also the work may be held in any
other way. The rationale of the operation will be explained by reference
to the diagrams Figures 3, 4, 5, 6, and 7. In these diagrams a, b, c, is
an equilateral triangle representing the cross section of the tool H,
d marking the point of the tool. In Figure 7 the triangle is shown in
the middle of a square e, f, g, h, representing the square opening in the
guide G. The line i, f, in this Figure shows the amount of play
necessary to the proper operation of the tool in a guide of this size. In
Figures 3, 4, 5, and 6 the triangles a, b, c, represent the four positions
of the tool in relation to the square opening in the guide G assumed
during one revolution. The action appears to be as follows:-When the
point d of the tool encounters the surface of the wood or metal to be
bored it meets with sufficient resistance to thrust it to one side until one
of the angles of the tool is driven into one of the angles of the guide;
it then occupies, let us suppose, the position represented in Figure 3.
in that position the angle c becomes a centre of rotation and the angle b
describes the arc b, f; this brings the tool into the position represented
in Figure 4; here the point 6 becomes a centre, and the point a
describes the arc a, f; this brings the tool into the position represented
in Figure 5, where the point a becomes a centre, and the point c
describes the arc c, f. The tool is now in the position shown in
Figure 6, point c becoming a centre, and the point 6 describing arc b, e.

page_text: This last movement brings the tool into its initial position in relation to
the guide, with the exception that the side b, c, of the tool is in contact
with the left side of the guide opening instead of the side a, c, as in
Figure 3. By changing the form of the guide angular holes of other
forms than square may be bored on the same principle of operation.
Practice will enable a skilful workman to use the tool without a guide
in an ordinary brace, giving the requisite eccentricity or play to the tool
by his judgment alone. The guide supplies the place of this skill to
inexperienced hands.
For boring in soft wood I propose to notch or groove the cutting edges
with spiral or gimlet-pointed grooves, which besides cutting faster
serve to feed or draw the tool into the wood.
Having described the nature of the said Invention, and the manner of
performing the same, I declare that what I claim as the Invention to be
protected by the herein-before in part recited Letters Patent is,―
1st. The triangular tool H with the pyramidal point working in the
guide G with the necessary eccentricity to reach the angles of the guide,
as described.
2ndly. The combination and arrangement of the clamping box B,
hollow standard E, tool stock I, and tool H in the manner and for the
purpose specified.
3rdly. A tool constructed as described for boring rectangular and
other angular holes by having an eccentric movement or "play" com-
municated to it by the operator in the manner set forth.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Twenty-ninth day of April, in
the year of our Lord One thousand eight hundred and seventy.
Witness,
W. G. E. SwINNOCK,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)