IMPROVEMENTS IN SELF COUNTER-SINKING WOOD SCREWS."
Year: 1881

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of IMPROVEMENTS
IN SELF COUNTER-SINKING WOOD SCREWS." A communication from abroad'
by John Eckford, Real Estate Agent, San Antonio, in the County of Bexar,
State of Texas, United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 14th January 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN SELF-COUNTER-SINKING WOOD
SCREWS." [A communication from abroad by John Eckford, Real Estate Agent,
of San Antonio, in the County of Bexar, State of Texas, United States of America.]
The object of this Invention is to make a self-countersinking screw-head that
will work in all kinds of wood, and clear itself of bore dust.
The Invention consists of a screw-head, having on the underside or bevel thereof
a series of bits or cutting edges alternating with flat and deep interspaces or
notches, said notches completely filling the circuit of the screw-head, and the
notches gradually increasing in width and depth from the screw-shank to the:
crown of the head, thus enabling the cutters to clear themselves.
In making the improved screw-head, I take a suitable blank and force the same
while hot into a die, and thus stamp out the cutting edges and the intervening
deep notches, forming a circle or series of cutters alternating with deep notches,
and completely filling the bevel or under side of the head. These cutters or edges
may be, say, a dozen, more or less, according to the size of the screw head and
other circumstances, all projecting sharply, like the cutting edges in a worm-bit or
auger. Both the cutting edges and the interspaces increase in size from the shank
or stem of the screw to the crown or outer edge of the head. The crown of the
screw head is completely serrated, and the interspaces between the teeth or cutters
are very deep, or of sufficient size and number to carry the bore dust, and throw
the same out above the head, and thus completely clear themselves and prevent
clogging. This screw head when in operation brings only the series of sharp edges
in contact with the solid or uncut wood. Both the cutting edges and the inter-
spaces have flat sides, and these planes meet at sharp angles, thus forming good
cutters, or in effect a good working bit or auger for boring the necessary counter
sink to receive the head of the screw, and also giving plenty of room in the
interspaces for the bore-dust, which is, freely ejected from the top of the screw,
even when the head has been completely sunk into the wood.

page_text: 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
12th July 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. " IMPROVEMENTS IN SELF COUNTERSINKING WOOD 5
SCREWS." A communication from abroad by John Eckford, Real Estate Agent,
of San Antonio, in the County of Bexar, State of Texas, United States of America.
The object of this Invention is to make a self countersinking screw head that
will work in all kinds of wood, and clear itself of bore dust.
The Invention consists of a screw head, having on the underside or bevel thereof 1
a series of bits or cutting edges alternating with flat and deep interspaces or
notches, said notches completely filling the circuit of the screw head, and the
notches gradually increasing in width and depth from the screw shank to the
crown of the head, thus enabling the cutters to clear themselves.
In the accompanying Drawings, Figure 1 is a side view of the improved screw,
the head thereof being countersunk in a piece of wood shown in section; Figure 2
is a top view of the improved screw head; Figure 3 is a bottom view of the
complete screw; Figure 4 is a top view of the screw head, the same being
countersunk in a piece of wood, as shown in Figure 1; Figure 5 is a top view of a
die for stamping out or forming the screw-head; Figure 6 is a side view of a blank
screw head before the same is forced into the die, Figure 5, to form the cutting
edges and intervening notches.
In making the improved screw head, I take a suitable blank, as shown in
Figure 6, and force the same while hot into the die, Figure 5, and thus stamp out
the cutting edges A, and the intervening deep notches B, forming a circle or series
of cutters alternating with deep notches, and completely filling the bevel or
underside of the head. These cutters or edges A may be, say, a dozen, more or less,
according to the size of the screw head and other circumstances, all projecting
sharply like the cutting edges in a worm-bit or auger. Both the cutting edges A
and the interspaces B increase in size from the shank or stem of the screw to the
crown or outer edge of the head. The crown of the screw head is completely
serrated, as shown in Figure 2, and the interspaces between the teeth or cutters are
very deep, or of sufficient size and number to carry the bore-dust, and throw the
same out above the head, and thus completely clear themselves and prevent
clogging.
The screw head when in operation brings only the series of sharp edges in contact
with the solid or uncut wood, as represented in Figure 4. Both the cutting edges
and the interspaces have flat sides, and these planes meet at sharp angles, thus
forming good cutters, or in effect a good working bit 'or auger for boring the
necessary countersink to receive the head of the screw, and also giving plenty of
room in the interspaces for the bore-dust, which is freely ejected from the top of
the screw, even when the head has been completely sunk into the wood, as seen in
Figure 1.
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,-
In a countersinking screw head having notches or cutting edges on the underside
or bevel thereof, the continuous series of cutters A and deep and flat interspaces or
notches B, completely filling the circle or bevel of the head, said notches opening

page_text: through the top of the head, and thus forming the serrated crown, as shown in
Figure 2, substantially as and for the purposes set forth.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Eighth day of July, A.D. 1881.
A
A. M. CLARA.
(L.B.)