IMPROVEMENTS IN MACHINERY FOR CUTTING DOVETAIL MORTISES, AND DOVETAIL PINS OR TENONS
Year: 1870

page_text: LETTERS PATENT to Robert Thompson, of Hoxton, in the County
'
of Middlesex, Engineer, for the Invention of "IMPROVEMENTS IN
MACHINERY FOR CUTTING DOVETAIL MORTISES, AND DOVETAIL PINS OR
TENONS."
Sealed the 10th March 1871, and dated the 14th September 1870.
PROVISIONAL SPECIFICATION left by the said Robert Thompson at
the Office of the Commissioners of Patents, with his Petition, on
the 14th September 1870.
I, ROBERT THOMPSON, of Hoxton, in the County of Middlesex,
Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MACHINERY FOR CUTTING DOVETAIL MORTISES AND DOVETAIL
PINS OR TENONS," to be as follows:―
This Invention relates, first, to improved arrangements of machinery
for cutting dovetail mortises in wood, for cabinet or other work. For
this purpose two rotary saws are arranged across and at angles to each
other for cutting the angular sides of each dovetail mortise. The axes
of the saws revolve in swivel bearings, which are capable of adjustment

page_text: to vary the angles at which the saws are required to operate in cutting
dovetail mortises more or less angular in shape. A third saw is by
preference employed to divide, and thus facilitate the removal of the
waste piece, which is cut out to form the dovetail mortise by means of a
stationary cutter, the point of which enters the central saw cut after the
angular saw cuts are made, the sides of the cutter acting to cut out the
waste piece and thus complete the dovetail mortise.
In order to cut or form a series of dovetail mortises corresponding
accurately with each other, upon the edges of a number of pieces of
wood of equal dimensions, the latter are laid one upon another on a
horizontal slide carried by a vertical slide, the wood to be cut being fixed
securely-by-a-lever, or otherwise, the series of pieces of boards being
placed at a proper distance over the saws. The vertical slide with the
work thereon being capable of moving up and down. In its downward
course, the wood is brought in contact with the circular saws and cutter
(or cutters) which passes through the board or boards, and cuts the
dovetail mortise. The vertical slide is then raised to the proper height
to bring the board or boards clear of the saws, the cross slide is shifted
to the next division, and the vertical slide is again pressed down with
the work on to the saws and cutters which pass through the board or
boards, and this is continued until the dovetail mortises are all cut.
The saws operate on the work as follows:-The two lower saws cut the
required angles of the dovetail mortises, the top saw working in line
between the two lower saws, the three saws cut the same depth in the
wood and take the greatest part of the wood away in the shape of sawdust.
The fixed cutter which is made the size of the bottom or largest part
of the dovetail cuts away the remaining and completes the dovetail
mortise.
For cutting dovetail pius or tenons, according to my Invention, to the
top of the table of the machine a bracket is fitted with a slide and rotary
cutter. This bracket is arranged to partially rotate and is set to the same
angle as the dovetail mortise. For cutting the dovetail pins or tenons,
the vertical slide is made a fixture by being bolted to the framing on
which it slides, but the cross slide is used for moving the work from one
division to another in succession, the board or boards to be cut being
placed thereon. The slide carrying the rotary cutter and shaft which is
driven at a very high speed is pressed down through the board or boards,
and shapes one side of the dovetail pins or tenons and in like manner

page_text: the slide is again raised for the cutter to clear the wood. The cross slide
carrying the work is then moved to the next division, the slide is again
pressed down, carrying the cutter with it to force the same through the
work; this is repeated till one side of the required number of dovetail
pins are cut. The boards are then ranged in the opposite direction and
the bracket, with slide and cutter, is placed to the opposite angle, and the
process as before is again carried out, and by these means the dovetail pins
or tenons are completely shaped and fit and join with the dovetail mortises.
For work where dovetails are large the same gear with suitable cutters
may be employed to cut both dovetail pins and mortises, the latter being
cut by a rotating cutter.
In cutting blind dovetails, such as are used for drawer fronts or other
similar purposes, two vertical spindles or shafts are mounted on two
slides, which are fitted to a cross beam on which one of these spindles is
driven at a very high speed by band and pullies in the ordinary manner,
the other is not driven but slides backwards and forwards to suit the
work, and is raised and lowered by a lever or otherwise. One spindle is
fitted with a dovetail cutter which is made to revolve, and is set down to
the proper depth by a lever and screw. This cutter cuts the dovetail
shape, whilst the other shaft is fitted with a flat or chisel-shaped
dovetail cutter which finishes and completes the work.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Robert Thompson in the Great Seal. Patent Office
on the 14th March 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
THOMPSON, of Hoxton, in the County of Middlesex, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of September, in the
year of our Lord One thousand eight hundred and seventy, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert Thompson, Her special licence that I,
the said Robert Thompson, my executors, administrators, and assigns, or
such others as I, the said Robert Thompson, my executors, administrators,
and assigns, should at any time agree with, and no others, from time

page_text: a, b, c, are three circular saws arranged to revolve one above the other,
as shown. The top saw a revolves at right angles to the horizontal
line of the slide g, whilst the saws b and c revolve at angles thereto,
the position of the saws being capable of adjustment, so as to vary the
angles at which they revolve to suit the particular form of dovetail
mortice they are required to cut. The saw a is employed to divide and
thus facilitate the removal of the waste piece, which is cut out to form
the dovetail mortice by means of a stationary cutter d, the point of
which enters the central saw cut made by the saw a after the angular
saw cuts are made, the sides of the cutter d acting to cut out the waste
wood and thus complete the dovetail mortice. The axis of the saw a
revolves in bearings a' carried by a slide block a², which can be moved
to and fro in the bracket a³ (formed or fixed on the framing ƒ) by
means of the set screw a', in order to adjust the position of the saw to
the depth of cut required. The axes of the saws b and c revolve in
swivel or rotating bearing b', c¹, which are formed with vertical pins or
axes 6*, c*, arranged so as to rotate in the sliding blocks b, c, the latter
being capable of moving to and fro in the brackets b³, c³, (on the
framing,) by means of the set screws b*, c', so as to adjust the position
and angles at which the saws b, c, are required to revolve, as will be
readily understood on examining Figure 4 and 5 of the Drawings, which
shows separate views of some of the parts full size. By this means the
angular position of the saws b and c can be varied so as to cut the sides
of dovetail mortices more or less angular in shape. Rotary motion is
communicated to the saws a, b, c, by means of bands passing partly
around the pullies a, b, c, such bands passing over pullies on a
driving axis, as shown at Figure 3 in the Drawings, actuated either by
hand or other motive power.
In order to cut or form a series of dovetail mortices corresponding
accurately with each other upon the ends of a number of pieces of wood
of equal dimensions, the latter are laid one upon another (as shown
at e, e, in the Drawings) on the horizontal slide g, carried by the vertical
slide f, the pieces of wood to be cut being fixed-securely upon the
upper surface of the slide g, between the vertical plate h¹ and links h³,
by the bars and clamping screw h, the arrangement of which will be
herein-after more particularly described. The slide g with the series of
pieces of wood or boards e, e, arranged thereon (the end of the bottom
board being just above the top saw a) is allowed to descend by turning

page_text: the hand wheel f³, which actuates the slide f¹ upon which the slide I is
mounted. The ends of the boards in their descent are first brought in
contact with the saw a, which makes a cut at right angles therein, and
as the boards pass downwards they come successively in contact with
the saws b and c, angular cuts being made thereby to form the sides of
the dovetail mortises. Having passed the saws the point of the fixed
cutter d enters the central saw cut and cuts away the waste wood, so
as to complete the dovetail mortices thus formed in each of the series of
boards e, e.
The three saws thus arranged make cuts of equal depth
in the ends of the boards e, e, and remove the greater part of the wood
in the form of sawdust, the fixed cutter .d (the width of which corre-
sponds with the bottom-or-largest-part-of-the-dovetail-mortice) cutting
away the unsevered portions of the waste wood to complete and perfect
the mortice. After the vertical slide f¹ has been again raised clear above
the saws the horizontal slide g with the boards thereon is caused to
travel sideways (by turning the hand wheel 94), the distance required
for cutting the next of the series of dovetail mortices (one in the end of
each board e), and this distance may be regulated and determined by
means of an index and pointer j, as shown at Figure 7 of the Drawings.
The slide f' again descends to cut another row of mortices in the series
of boards e, e, and so on in succession until the whole of the series are
completed.
I will now proceed to describe another mode of cutting dovetail
mortices in the ends of a series of boards in accordance with another
part of my improvements, the mechanism employed for this purpose
being either arranged upon the same f in combination with the
saws a, b, c, as previously described, or such mechanism may be mounted
upon a separate frame, as shown in Figure 6, 7, and 8 of the Drawings,
which is the arrangements I prefer to employ for cutting dovetail
mortices when they are so large as to admit of the use of a rotary cutter
formed in accordance with this part of my improvements as to cut
dovetail mortices of the required form and dimensions by causing such
rotary cutters to descend through the end of a board or series of boards
at one operation.
Figure 6 is a plan, Figure 7 a front view, and Figure 8 an end view
of a machine for cutting dovetail mortices (or dovetail pins or tenons, as
hereafter described,) by means of rotary cutters according to this part
of my improvements.

page_text: As similar mechanism is arranged for actuating rotary cutters for
cutting dovetail mortices and dovetail pins or tenons upon the frame f
in combination with the saws a, b, c, as shown in Figures 1, 2, and 3,
I will mark corresponding parts in all Figures with similar letters of
reference, so that the description previously given of any of the parts
which correspond in cither arrangement need not be repeated.
22
The series of boards e, e, to be operated upon for cutting dovetail
mortices by means of the rotary are placed one over another, as
shown at Figure 7, being securely held upon the horizontal slide y by
the clamping bars and screw h, and the slide is caused to traverse to
and fro horizontally by means of a rack and pinion to move the work
from one division to another, as previously described in reference to the
first part of my improvements; but in this arrangement the vertical
slide f¹is not required, and is made a fixture when rotary cutters are
employed in the arrangement of machinery shown in Figures 1, 2, and 3,
the slide being fixed to the framing by set screws or bolts, as pre-
viously described, or otherwise fixed whilst such rotary cutters are in
use. It will be seen that the rotary cutter i corresponds in form with
the angular form of the dovetail mortice it is required to cut, the cutter i
being fixed at the end of the axis 2, which revolves in bearings 2 upon
the slide 3, sliding up and down upon guides formed on the arm or
bracket, which is supported by and partially rotates on the pin or
axis upon the stationary bracket fixed upon the table of the
machine. The arm or partially rotating bracket carrying the slide
and rotary cutter i can thus make a partial revolution upon the pin or
axis when required, being set and fixed in any desired position by the
set screw or bolt passing through a curved slot in the curved plate 28
forming part of the bracket **, and through a curved slot in the fixed
bracket. The axis is driven by means of a band passing partly
around the pulley fixed on the axis ³, and over a pulley upon a radial
frame (not shown in the Drawings) arranged so as to compensate for
the movement of the axis with the slide , as will be readily under-
stood by a competent mechanic. The slide i³ is moved up and down
upon its guides when required by means of the hand lever 10 moving
on a pin joint or fulcrum at " upon the arm ¹ forming part of the
bracket and curved plate 8, the short arm of the lever 10 being con-
nected by a jointed link i¹³ to the slide ³. By raising the hand lever ¿¹º
the slide will be caused to descend and force the rotary cutter i

page_text: through the ends of the series of boards e, e, so as to cut a dovetail
mortice of the form of a cutter in the ends of each of the boards. The
slide and cutter i is then raised, and the horizontal slide with the bands
or boards e, e, is moved a sufficient distance for cutting the next of the
series of dovetail mortices therein by the next descent of the rotary
cutter i, as previously described, and so on in succession until the whole
series are cut. The amount of the horizontal movement of the slide
to determine the distance between each of the dovetail mortices is
governed by the index j and dividing bar or bars and suitable stops,
as shown at Figure 7. The rotary cutter in passing through the bottom
board e passes down into a groove in a block e* fixed upon the top
_surface or table-of-the-machine, such block acting as a support to the
lower edges of the
whilst the cutter is passing through the
bottom board.
I would here remark that I am aware that dovetail mortices have
before been cut by means of rotary cutters corresponding in form with
the dovetail mortice to be cut thereby, I therefore make no claim to the
use of rotary cutters of such form or shape, except when they are made
with a lip or return edge i*, as shewn at Figure 11, for cutting the end
grain of the wood at the inner end or bottom of the mortice, such cutters
being mounted upon an axis carried by a slide, so as to force the rotating
cutter i through a series of boards, as previously described.
I will now describe my improvements in machinery for cutting
dovetail pins or tenons, which is effected by the same arrangement of
mechanism as that last described, differing only in the form of the rotary
cutter employed and the mode of arranging the boards e, c, upon the
slide g.
Figures 12 and 13 shew separate views (differing slightly in form) of
the form of the rotary cutter I employ for cutting dovetail pins or tenons
according to this part of my improvements. The sides of the cutter are
parallel, a lip or return cutting edge i at the end acting to cut the
cross grain of the wood at the bottom of the spaces between the pins.
Figure 14 is a similar cutter, the cutting edge being twisted or winding
round its axis.
In order to cut or form the angular sides of the tenon pins the
boards e, e, are arranged one upon another on the horizontal slide g,
with the edges overlapping each other, so as to correspond with the
angle at which the rotary cutter is to pass through the series of boards,

page_text: as shown at Figures 9 and 10, which represents the boards e, e, arranged
upon the slide overlapping each other in opposite directions. The
position of the boards e, e, on the slide g is accurately determined by
plucking their edges against the inclined surface of the plate or fence ¹,
which is supported and partially rotates upon the pin or axis h² on the
bracket h³ fixed upon the top of the horizontal slide g. The plate or
fence can be set at any desired angle by means of a set screw or
bolt * passing through curved slots in the curved plate at the back
of the fence and in the fixed bracket h³. h*, *, are parallel bars
jointed to the top and bottom of the plate or fence h¹, as shown. These
bars are connected by the sliding blocks and links ³, the blocks being
fixed in any desired position upon the bars * by set screws, as shewn,
with the links ³ resting against the edges of the boards at a corre-
sponding angle with the fence ', so that when the fence is moved
from one angular position to another the links h³ will assume the same
angle, and thus move the series of boards with them up to the fence ¹
into the position required for cutting the angular sides of the tenor pins.
The boards e, e, are held down by the clamping screw h, which passes
through the cross bar ** sliding on the bars *. Having arranged the
series of boards e, e, so as to correspond with the inclined position at
which the slide and rotary cutter is placed, as shewn at Figures 9, for
cutting one side of the tenons or pins, the rotating cutter is then forced
through the series of boards, so as to shape or form one side of the
tenon or pins to the angle required, which is determined by the angle
or incline at which the cutter slide is set and fixed, which incline must
correspond with the angle of the dovetail mortice. The slide is again
raised for the cutter to clear the wood; the horizontal slide g carrying
the work is then moved to the next division, and the slide with the
rotating cutter is again pressed down through the series of boards, these
operations being repeated until one side of the series of tenon pins are
cut. The board e, e, are then arranged in the opposite direction by
placing the fence at the opposite angle or incline, the inclined portion
of the slide and cutter being also reversed, as shewn at Figure 10, so
as to cut the other angular sides of the tenons or pins by repeating the
operations upon the series of boards, as previously described, by which
the series of tenons or pins will be completed.
<<
blind dovetail
I will now describe my improvements in cutting
pins or tenons, such as are used for drawer fronts or other similar
purposes.

page_text: Figure 15 is a plan of so much of a machine as will enable me to
describe this part of my improvements. For this purpose I prefer to
employ either of the rotary cutters (shown separately at Figures 12, 13,
and 14, mounted on an axis and slide 3, actuated by a lever 210, as
previously described), which first cuts out the spaces between the pins
or tenons, as shown by the end view and plan of a piece of board at
Figure 16. One board only is operated upon at a time, being fixed upon
the slide g, which is moved to and fro to cause the rotary cutter i to
cut from end to end of the space between each pin. Curved corners are
left at the end of each space between the pins, as shown by dotted lines,
which are removed to form the angular sides of the pins in the following
manner: When the slide-g-is-moved with the board to the next
division or space the slide and rotary cutter is again pressed down
into the board to the depth required, and in its decent one end of a
lever k, moving on a pin joint at ¹ on the slide 3, is brought in contact
with a fixed stud k* or projection on the table f, causing the opposite
end of the lever k, which carries an angular shaped cutter or chisel
(shown separately full size at Figure 17), to descend into the space pre-
viously cut by the rotary cutter; and as the slide g and board is moved
to and fro the cutter / cuts the end grain of the wood left at the ends
of the space between the pins by the rotary cutter, the angular sides of
the cutter corresponding with the angular sides of the dovetail pin
required to be cut. These operations are repeated until the whole of
the spaces between the pins are cut; and on the return movement of
the slide g each space is brought in succession opposite the sliding tool
or cutter m (shown separately at Figure 18). The cutter m, which corre-
sponds in form with the space between the dovetail pins, is mounted on
the end of a sliding rod m', which is moved to and fro by means of the
lever m², so as to force the cutter m into the space between the dovetail
pins to cut out the curved corners left by the rotary cutter to complete
the work, the end of the cutter m being formed with sharp edges for
this purpose.
The slide which carries the rod and cutter m can be
adjusted to any desired position upon the guide m³, and the cutters may
be arranged to work either in a vertical or horizontal position as may be
desired.
Having thus described the nature of my Invention, and the manner in
which the same is carried into practice, I would have it understood that
I do not confine myself to the exact detail herein described, so long as
the main features of my Invention be retained; but what I claim is,

page_text: ·First. The arrangement and application of the circular saws a, b, c,
and cutter d for cutting dovetail mortices of angular form in one or a
series of boards, substantially in the manner herein described and shown
in reference to Figures 1, 2, 3, 4, and 5 of the Drawings hereunto
annexed.
Secondly. I claim the mode of cutting dovetail mortices in one or a
series of boards by means of a rotary cutter i mounted upon a slide ³,
arranged and actuated substantially in the manner hercin described
and shown in reference to Figures 1, 2, 3, 6, 7, and 8 of the Drawings
hereunto annexed.
Thirdly. I claim the mode of cutting dovetail pins or tenons by means
of a rotary cutter mounted upon an adjustable slide ³, substantially in
the manner herein described and shown in reference to Figures 6, 7,
and 8 of the Drawings hereunto annexed.
Fourthly. I claim the mode of cutting "blind dovetails" by means of
a rotary i, cutters and m, substantially in the manner herein described
and shown in the Drawings hereunto annexed.
Fifthly. I claim the construction of rotary cutters for cutting dovetail
mortices or dovetail pins or tenons with a lip or return cutting edge i*,
as shown at Figures 11, 12, 13, and 14 of the Drawings hereunto annexed.
Lastly. I claim the general arrangement and combination of machinery
for cutting dovetail mortices and dovetail pins or tenons, as herein
described and shown in the Drawings hereunto annexed.
In witness whereof, I, the said Robert Thompson, have hereunto set
my hand and seal, this Thirteenth day of March, in the year of
our Lord One thousand eight hundred and seventy-one.
Witness,
J. G. TONGUE,
Patent Agent,
ROBERT THOMPSON.
(L.S.)
34, Southampton Buildings,
Chancery Lane, W.C.

page_text: thousand eight hundred and seventy, did grant unto me, the said Robert
Thompson, my executors, administrators, and assigns, the sole privilege
to make, use, exercise, and vend, the Invention of "IMPROVEMENTS IN
MACHINERY FOR CUTTING DOVETAIL MORTISES AND DOVETAIL PINS OR TENONS,"
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and the Isle of Man, during the term of fourteen years thence
next ensuing :
And whereas I, the said Robert Thompson, on the Fourteenth day
of March One thousand eight hundred and seventy-one, within the
time prescribed by the said Letters Patent, did cause a Specification in
writing under my hand and seal to be filed in the Great Seal Patent
Office:
And whereas, since the filing of the said Specification, I have been
informed and advised that a very similar arrangement of machinery for
cutting dovetail mortises and dovetail pins or tenons to that described
and claimed in reference to Figures 6, 7, 8, 9, and 10 of the Drawings
appended to my said Specification was in use prior to the date of the
said Letters Patent granted to me; and I am further advised that
there is not sufficient novelty in that particular arrangement of machinery
to enable me to support the validity of the second and third claims
contained in my said Specification; and I do hereby disclaim the said
second and third claiming causes; consisting of the following words con-
tained in lines 6 to 14, page 11, inclusive of the Specification as printed
and published by the Commissioners of Patents, viz.: "Secondly, I
“claim the mode of cutting dovetail mortices in one or a series of boards
and strike out
"by means of a rotary cutter 2. mounted unon a slide 3 arranged and
and insert the word "Thinlly:"
A
page 11, I strike out the word " Fourthly," and in line 16, page
11, I insert the word "cutter" after the word "rotary," and the word
"and" after the letter "i" in the same line. And in order to limit the
meaning of the last claiming clause in line 23, page 11, after the
words "shewn in" I insert the following figures and words, viz.,

page_text: Figures 1, 4, 0, 4, 3, and 1. I am also desirous of discaming parts OF
and of altering and amending the Specification of the said Letters Patent
in the manner herein-after set forth, videlicit :-
"
In line 5, page 4, of the said printed Specification, I alter the spelling
of the word "mortice" in the title to the Invention by striking out the
letter "c," and substituting the letter "s" therefor. I also strike out
the letter "c" and substitute the letter " S where this error occurs in
the words "mortice" and "mortices," in line 17, page 4, also in lines 6, 8,
11, 24, and 29, page 5, also in lines 6, 8, 12, 14, 17, 20, 24, 30, 32, and
36, page 6, also in lines 2, 8, and 19, page 7, also in lines 2, 5, 8, 15, and
20, page 8, also in line 26, page 9, and in lines 2, 19, and 22, page 11 of
the said printed Specification. The word "revoke," after the words
"The axes of the saws b and c,” in the Specification filed by me, I strike
out and insert the word "revolve." In line 16, page 5, of the printed
Specification, I strike out the word
"bearings." In line 21, page 5, I
"
bearing," and insert the word
strike out the word "Figure,"
and in line 22, page 5, I strike out the word "shows," and insert the word "show."
Figures,"
"
A
and insert the word ""
word "make," and insert the word
66
do hereby
A
In line 3, page 6, I strike out the
makes," and in lines 24 and 25,
do hereby
י
page 6, I strike out, and disclaim the words "in accordance with
O another part of my improvements." In line 26, page 6, after the word
same," I insert the word " frame." In line 29, page 6, I strike out
the word "arrangements," and insert the word "arrangement," and after
the words "I prefer to employ," in the same line 29, page 6, I insert the
words "although I make.no claim to such an arrangement." In lines 37
and 38, page 6, I strike out and disclaim the words "according
to this part of my improvements." In line 8, page 7, after the word
rotary I insert the word "cutter." In line 2, page 8, I strike out
the letter a " and insert the word "the," and in line 3, page 8, I
strike out the word "bands," and insert the word board. In line 13,
page S, after the words "lower edges of the," I insert the word
"mortise." In line 23, page 8, I strike out and
"
do hereby
A
disclaim the
words "my improvements in," and after the letter g in line 27, page 8
I insert the words "to which arrangement of the boards I make no
claim. In line 4, page 9, I strike out the word "plucking," and insert
the word "placing." In line 17, page 9, I strike out the word "tenor,"

page_text: And I do hereby declare that the said Specification as amended by
this present Disclaimer and Memorandum of Alteration shall read and
be as follows:-
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
THOMPSON, of Hoxton, in the County of Middlesex, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fourteenth day of September, in the
year of our Lord One thousand eight hundred and seventy, in the thirty-
fourth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Robert Thompson, Her special license that
I, the said Robert Thompson, my executors, administrators, and assigns,
or such others as I, the said Robert Thompson, my executors, ad-
ministrators, 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, usc, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN MACHINERY
FOR CUTTING DOVETAIL MORTISES AND DOVETAIL PINS OR TENONS," upon the
condition (amongst others) that I, the said Robert Thompson, my
executors or administrators, by an instrument 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

page_text: Figure 1 shows a plan, Figure 2 a front view, and Figure 3 an end
view of machinery arranged in accordance with my improvements.
is the framing of the machine, and f¹ is a vertical slide arranged to
move up and down on guides fupon the front of the framing ƒ by
means of toothed pinions on the axis, taking into the toothed racks *
fixed on each side of the framing, the axis f³ being actuated by the
hand wheel to raise and lower the slide f' as required. The slide f¹
is retained when at its highest position by set screws or bolts f* entering
suitable holes in the guide platef° and framing ƒ. g is a transverse hori-
zontal slide carried by the vertical slide f¹. The slide is moved to and
fro on guides g¹ by the toothed pinion g, which takes into a toothed
rack on the under side of the slide g. The axis of the pinion g² is
carried by the slide", and is actuated by the hand wheel to move the
slide to and fro as required.
I
a, b, c, are three circular saws arranged to revolve one above the other
as shown. The top saw a revolves at right angles to the horizontal line
of the slide g, whilst the saws b and c revolve at angles therecto, the
position of the saws being capable of adjustment so as to vary the angles
at which they revolve to suit the particular form of dovetail mortise
they are required to cut. The saw a is employed to divido and thus
facilitate the removal of the waste piece which is cut out to form the
dovetail mortise by means of a stationary cutter d, the point of which

page_text: enters the central saw cut made by the saw a after the angular saw cuts
are made, the sides of the cutter d acting to cut out the waste wood
and thus complete the dovetail mortise. The axis of the saw a revolves
in bearings a¹ carried by a slide block, which can be moved to and fro
in the bracket a³ (formed or fixed on the framing) by means of the set
screw a' in order to adjust the position of the saw to the depth of cut
required. The axes of the saws b and c revolve in swivel or rotating
bearings b¹, c¹, which are formed with vertical pins or axes U*, c*,
arranged so as to rotate in the sliding blocks b, c, the latter being
capable of moving to and fro in the brackets 1, 3, (on the framing) by
means of the set screws U², c', so as to adjust the position and angles at
which the saws b, c, are required to revolve, as will be readily understood
on examining Figures 4 and 5 of the Drawings, which shew separate views
of some of the parts full size. By this means the angular position of the
saws and c can be varied so as to cut the sides of dovetail mortises
more or less angular in shape. Rotary motion is communicated to the
saws a, b, c, by means of bands passing partly around the pullies a³, 65, C³,
such bands passing over pullies on a driving axis, as shown, at Figure 3
in the Drawings, actuated either by hand or other power.
motive
A
In order to cut or form a series of dovetail mortises corresponding
accurately with each other upon the ends of a number of pieces of wood
of equal dimensions, the latter are laid one upon another (as shown at
e, e, in the Drawings) on the horizontal slide g carried by the vertical slide
f, the pieces of wood to be cut being fixed securely upon the upper
surface of the slide g, between the vertical plate and links ½³ by the
bars and clamping screw h, the arrangement of which will be herein-
after more particularly described. The slide g with the series of pieces
of wood or boards e, e, arranged thereon (the end of the bottom board
being just above the top saw a) is allowed to descend by turning the hand
wheel which actuates the slide f¹ upon which the slide g is mounted,
the ends of the boards in their descent are first brought in contact with
the saw a which makes a cut at right angles therein, and as the boards
pass downwards they come successively in contact with the saws b
and c, angular cuts being made thereby to form the sides of the dovetail
mortises. Having passed the saws the point of the fixed cutter d enters
the central saw cut and cuts away the waste wood, so as to complete the
dovetail mortises thus formed in each of the series of boards e, e, the
three saws thus arranged made cuts of equal depth in the ends of the

page_text: boards e, e, and remove the greater part of the wood in the form of saw-
dust, the fixed cutter a (the width of which corresponds with the bottom
or largest part of the dovetail mortise) cutting away the unsevered
portions of the waste wood to complete and perfect the mortise. After the
vertical side has been again raised clear above the saws the horizontal
slide with the boards thereon is caused to travel sideways (by turning
the hand wheel g₁) the distance required for cutting the next of the
series of dovetail mortises (one in the end of each board e) and this
distance may be regulated and determined by means of an index and
pointer as shewn at Figure 7 of the Drawings. The slide f¹ again
descends to cut another row of mortises in the series of boards e, e, and
so on in succession until the whole of the series are completed.
an
A
I will now proceed to describe another mode of cutting dovetail
mortises in the ends of a series of boards, the mechanism employed
for this purpose being either arranged upon the same frame f, in
combination with the saws a, b, c, as previously described, or such
mechanism may be mounted upon a separate frame, as shown in Figures
6, 7, and 8 of the Drawings, which is the arrangement I prefer to
employ, although I make no claim to such arrangement for cutting
dovetail mortises when they are so large as to admit of the use of a
rotary cutter formed in accordance with this part of my improvements,
as to cut dovetail mortises when-they-are-so-large-as-to-admit-of-the-use-of
a-rotary-eutter-formed-in-accordance-with-this-part-of my improvements-as-to-eut
dovetail-mortises of the required form and dimensions by causing such
rotary cutters to descend through the end of a board or series of boards
at one operation.
Figure 6 is a plan, Figure 7 a front view, and Figure 8 an end view of
a machine for cutting dovetail mortises (or dovetail pins or tenons, as
hereafter described,) by means of rotary cutters.
As similar mechanism is arranged for actuating rotary cutters for
cutting dovetail mortises and dovetail pins or tenons upon the frame f
in combination with the saws a, b, c, as shown in Figures 1, 2, and 3,
I will mark corresponding parts in all these Figures with similar letters
of reference, so that the description previously given of any of the parts
which correspond in either arrangement need not be repeated.
The series of boards e, e, to be operated upon for cutting dovetail
mortises by means of the rotary cutter i are placed one over another,

page_text: as shown at Figure 7, being securely held upon the horizontal slide g by
the clamping bars and screw h, and the slide gis caused to traverse to
and fro horizontally by means of a rack and pinion to move the work
from one division to another, as previously described on reference to
the first part of my improvements, but in this arrangement the vertical
slide is not required, and is made a fixture when rotary cutters are
employed in the arrangement of machinery shewn in Figures 1, 2, and 3,
the slide being fixed to the framing by set screws or bolts, as
previously described, or otherwise fixed while such rotary cutters are in
lise. It will be seen that the rotary cutter i corresponds in form with
the angular form of the dovetail mortise-it-is-required-to-cut,-the-cutter-i
being fixed at the end of the axis ', which revolves in bearings upon
the slide sliding up and down upon guides formed on the arm or
bracket, which is supported by and partially rotates on the pin or
axis upon the stationary bracket & fixed upon the table of the machine.
The arm or partially rotating bracket carrying the slide and rotary
cutter i can thus make a partial revolution upon the pin or axis when
required, being set and fixed in any desired position by the set screw or
bolt passing through a curved slot in the curved plate forming part
of tlie bracket, and through a curved slot in the fixed bracket t.
The axis is driven by means of a band passing partly around the
pulley fixed on the axis i, and over a pulley upon a radial frame (not
shown in the Drawings) arranged so as to compensate for the movement
of the axis with the slide 23, as will be readily understood by a
competent mechanic. The slide is moved up and down upon its
guides when required by means of the hand lever " moving on a pin
joint or fulcrum at i¹¹ upon the arm ¹³, forming part of the bracket i and
curved plate i, the short arm of the lever being connected by a jointed
link to the slide . By raising the hand lever the slide will be
caused to descend and force the rotary cutter i through the ends of the
series of boards e, e, so as to cut a dovetail mortise of the form of the
cutter in the ends of each of the boards. The slide and cutter i is then
raised, and the horizontal slide g with the board or boards e, e, is moved a
sufficient distance for cutting the next-of the series of dovetail mortises
therein by the next descent of the rotary cutter i, as previously described,
and so on in succession until the whole series are cut. The amount of
the horizontal movement of the slide to determine the distance
between each of the dovetail mortises is governed by the index j and
dividing bar or bars j', and suitable stops, as shown at Figure 7. The

page_text: rotary cutter in passing through the bottom board e passes down into a
groove in a block e* fixed upon the top surface or table of the machine,
such block acting as a support to the lower edges of the mortise whilst
the cutter is passing through the bottom board.
I would here remark that I am aware that dovetail mortises have
before been cut by means of rotary cutters corresponding in form with
the dovetail mortise to be cut thereby, I therefore make no claim to the
use of rotary cutters of such form or shape except when they are made
with a lip or return edge i*, as shewn at Figure 11, for cutting the end
grain of the wood at the inner end or bottom of the mortise, such cutters
being mounted upon an axis carried by a slide so as to force the rotating
cutter i through a series of boards as previously described.
I will now describe machinery for cutting dovetail pins or tenons
which is effected by the same arrangement of mechanism as that last
described, differing only in form of the rotary cutter employed and the
mode of arranging the boards e, e, upon the slide g, to which arrange-
ment of the boards I make no claim.
Figures 12 and 13 shew separate views (differing slightly in form) of
the form of the rotary cutter I employ for cutting dovetail pins or tenons
according to this part of my improvements. The sides of the cutter are
parallel, a lip or return cutting edge i* at the end acting to cut the cross
grain of the wood at the bottom of the spaces between the pins. Figure
14 is a similar cutter, the cutting edge being twisted or winding round
its axis.
In order to cut or form the angular sides of the tenon pins the boards
e, e, are arranged one upon another on the horizontal slide g, with the
edges overlapping each other, so as to correspond with the angle at which
the rotary cutter is to pass through the series of boards, as shown at
Figures 9 and 10, which represents the boards e, e, arranged upon the
slide, overlapping each other in opposite directions. The position of the
boards e, e, on the slide is accurately determined by placing their edges
against the inclined surface of the plate or fence ', which is supported
and partially rotates upon the pin or axis ² on the bracket h³ fixed upon
the top of the horizontal slide g. The plate or fence h³ can be set at any
desired angle by means of a set screw or bolt * passing through curved
slots in the curved plate at the back of the fence h¹, and in the fixed
bracket h³, h', are are parallel bars jointed to the top and bottom of

page_text: the plate or fence ', as shown. These bars are connected by the sliding
blocks and links 5, the blocks being fixed in any desired position upon
the bars by set screws, as shewn, with the links 15 resting against the
edges of the boards at a corresponding angle with the fence ¹, so that
when the fence ¹ is moved from one angular position to another, the
links will assume the same angle, and thus move the series of boards
with them up to the fence into the position required for cutting the
angular sides of the tenon pins. The boards e, e, are held down by the
clamping screw h which passes through the cross bar **, sliding on the
bars. Having arranged the series of boards e, e, so as to correspond
-with-the-inclined-position-at-which-the-slide-and-rotary-cutter-is-
placed, as shewn at Figures 9, for cutting one side of the tenons or pins,
the rotating cutter is then forced through the series of boards so as to
shape or form one side of the tenon or pin to the angle required, which
is determined by the angle or incline at which the cutter slide i³ is set
and fixed, which incline must correspond with the angle of the dovetail
mortise. The slide is again raised for the cutter to clear the wood, the
horizontal slide g carrying the work is then moved to the next division,
and the slide with the rotating cutter is again pressed down through the
series of boards, these operations being repeated until one side of the
series of tenon pins are cut. The boards e, e, are then arranged in the
opposite direction by placing the fence at the opposite angle or incline,
the inclined portion of the slide and cutter being also reversed, as shewn
at Figure 10, so as to cut the other angular sides of the tenons or
pins by repeating the operations upon the series of boards as previously
described, by which. the series of tenons or pins will be completed.
I will now describe my improvements in cutting "blind dovetail" pins
or tenons such as are used for drawer fronts or other similar purposes.
Figure 15 is a plan of so much of a machine as will enable me to
describe this part of my improvements. For this purpose I prefer to
employ either of the rotary cutters (shown separately at Figures 12, 13,
and 14 mounted on an axis and slide, actuated by a lever 10 as
previously described) which first cuts out the spaces between the pins
or tenons, as shown by the end view and plan of a piece of board at
Figure 16. One board only is operated upon at a time, being being
fixed upon the slide g, which is moved to and fro to cause the rotary
cutter i to cut from end to end of the space between each pin. Curved
corners are left at the end of each space between the pins as shown by

page_text: left
A
dotted lines, which are removed to form the angular sides of the pins in
the following manner-When the slide 9 is moved with the board to
the next division or space the slide and rotary cutter is again pressed
down into the board to the depth required, and in its descent one end of
a lever moving on a pin joint at ¹ on the slide is brought in contact
with a fixed stud k* or projection on the table f, causing the opposite
end of the lever k, which carries an angular shaped cutter or chisel /
(shown separately full size at Figure 17), to descend into the space
previously cut by the rotary cutter, and as the slide g and board is
moved to and fro the cutter cuts the end grain of the wood at the
ends of the space between the pins by the. rotary cutter, the angular
sides of the cutter / corresponding with the angular sides of the dovetail
pin required to be cut. These operations are repeated until the
whole of the spaces between the pins are cut, and on the return
movement of the slide 9 each space is brought in succession opposite
the sliding tool or cutter m (shown separately at Figure 18). The
cutter m, which corresponds in form with the space between the
dovetail pins, is mounted on the end of a sliding rod m', which is
moved to and fro by means of the lever m², so as to force the cutter m.
into the space between the dovetail pins to cut out the curved corners
left by the rotary cutter to complete the work, the end of the cutter m
being formed with sharp edges for this purpose. The slide which
carries the rod and cutter m can be adjusted to any desired position
upon the guide m³, and the cutters may be arranged to work either in a
vertical or horizontal position as may be desired.
Having thus described the nature of my Invention, and the manner
in which the same is carried into practice, I would have it understood
that I do not confine myself to the exact details herein described,
so long as the main features of my Invention be retained, but what I
claim is,―
C,
First. The arrangement and application of the circular saws a, b,
and cutter d, for cutting dovetail mortises of angular form in one or a
series of boards substantially in the manner herein described and
shewn in reference of Figures 1, 2, 3, 4, and 5 of the Drawings
hereunto annexed.
Secondly. I claim the mode of cutting "blind dovetails" by means of
a rotary cutter i and cutters and m, substantially in the manner hervin
described and shown in the Drawings hereunto annexed.

page_text: I hereby grant my fiat, giving leave to the above-named Robert 1
Thompson to file in the Great Seal Patent Office, with the Specification
to which the same relates, the above-written' Disclaimer and Memo-
randum of Alterations.

page_text: left by the rotary cutter in the ends of the
blind dovetail spaces in place of the
cutters and m when the wood is
cross grained.
very