Improvements in Cutting Dovetails, Grooves, and Tenons, and Appliances therefor.
Year: 1889

page_text: Date of Application, 2nd Apr., 1889
Complete Specification Left, 16th Dec., 1889-Accepted, 25th Jan., 1890
PROVISIONAL SPECIFICATION.
Improvements in Cutting Dovetails, Grooves, and Tenons, and
Appliances therefor.
We THOMAS MAYHEW BEAR of Colchester, in the county of Essex, Manufacturer,
and HARRY RANSOM, of Sudbury in the county of Suffolk, Cabinet maker do hereby
declare the nature of this invention to be as follows:-.
This invention has for object the cutting of dovetails, grooves and tenons by means
of an ordinary circular saw.
For this purpose, we apply to a circular saw bench, an appliance consisting (when
cutting dovetails) of a frame adapted to slide upon the saw table and having two
adjustable inclined planes provided with gauges to suit the dovetail to be cut. The
wood to be dovetailed is placed upon the frame which frame is then passed against
the saw, a true and uniform cut for the mortice being thus obtained. When one line
of cuts has been thus made the wood is reversed and the second line of cuts made, a
chizel being employed to complete the mortices.
.
For cutting the tenons (or pins) a somewhat similar frame is used except that it is
horizontal. The wood is passed towards the saw upon this horizontal frame which is
pivotted at one end, the other end moving through a segment, the segmental move-
ment thus obtained ensuring angles of cut corresponding to the dovetail mortice.
For ordinary tenons and grooves the horizontal frame set square is used with proper
gauges.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Cutting Dovetails, Grooves, and Tenons, and
Appliances therefor.
We, THOMAS MAYHEW BEAR, of Colchester, in the county of Essex, manufacturer,
and HARRY RANSOM, of Sudbury, in the county of Suffolk, Cabinet-maker, do
hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
This invention has for object the cutting of dovetails, grooves and tenons by means
of an ordinary circular saw, and comprises the improvements hereinafter described.
In the accompanying drawings:
--
Figures 1, 2 and 3 are a front elevation, plan and side elevation respectively of
our improved appliances for cutting dovetails, grooves and tenons, the said appliances
being shewn applied to the top or table of a circular saw bench, the said top or table
being capable of adjustment.
Figure 4 is a plan of the frame or portion of the appliances for cutting grooves
and tenons, the said view illustrating the position the said frame occupies while
performing one part of the operation of cutting the tenons or pius for dovetails.
Figure 5 is a similar view to fig. 4 but illustrating the position the said frame
occupies while performing another part of the said operation.
Figure 6 is a front elevation of the portion of the apparatus for cutting the mortises
for dovetails.
Figure 7 is a view of a piece of wood after having been operated upon to produce
the tenons or pins for dovetails; and,

page_text: Figure 8 is a view of another piece of wood after having been operated upon to
produce the mortises for the same.
Figure 9 is a section illustrating the method of cutting a blind dovetail with our
improved appliances; and,
Figures 10 and 11 are an edge and side view respectively of a stop which we some-
times use in conjunction with our improved appliances.
Similar reference letters indicate the same parts throughout the drawings.
a is a base upon which are arranged two frames b and c, the frame 6 serving to
allow of grooves and tenons being cut by the saw d, while the frame c serves to allow
of the mortises, for dovetails being cut by the same means. The base a is provided
with a longitudinal slot a¹ through which the saw projects, and is capable of a
sliding movement upon the table e of the circular saw bench in the direction of the
said slot, the said base being provided with strips or runners a² which engage in
grooves e' in the said table.
We will first describe the construction and operation of the frame b. The said
frame, as shewn in figs. 1 to 5 consists of two rectangular frames connected by a
bridge-piece and is provided at its rear face with two ledges or shelves ² 6³, upon
each of which are arranged two strips of wood f having a series of equi-distant cuts
or marks, serving as gauge marks as hereinafter described; the said strips being
adjustably attached to the frame by screws 2 passed through slots f³. The lower
shelf 63 is divided in the centre so as to enable the saw d to pass through it when
the frame is moved as hereinafter described. The said shelf is slightly broader than
the upper one 62 so as to support the piece of wood to be operated upon,. as shewn
clearly in fig. 3, the said piece being represented by dotted lines at g. The frame b
is pivotted at / to a plate attached to the base a so that the said frame can be
adjusted horizontally in an angular position relatively with the slot a¹, as shewn at
figs. 4 and 5, a segmental slotted plate 2 being fixed to the base a, to which the said
frame can be clamped by the wing nut i and bolt a¹.
In order to make use of the frame b for cutting the tenons or pins for dovetails,
the said frame is adjusted and clamped, say, in the angular position represented in fig.
and the piece of wood to be operated upon is then placed upon the shelf 63, as shewn
by the dotted lines at g fig. 3, a pencil or other mark having first been made on the
rear surface of the edge to be operated upon of the said wood and near one end of
the same to show where the first saw cut is to be made. The piece of wood must then
be moved along the shelf 63 till the pencil mark is over the centre of the slot a¹, and
one of the upper or lower gauge strips must then be adjusted till one of its gauge
marks coincides or is even with one end of the said wood. If now the frame b
together with the wood which must be held tightly to the said frame by the hands of the
operator be advanced against the saw, the said saw being revolved will make a cut through
the wood at the pencil mark thereby forming one side of one of the tenons or pins, the
depth of the cut being of course regulated by the height to which the table of the bench
is adjusted by means of its screw e². The next cut must then be made by moving
the end of the wood out of line with the gauge mark herein before described and
making it coincide or even with the next adjacent gauge-mark, and by again advancing it
against the saw in a similar manner to that herein before described another cut will
be made similar to the first one. By repeating the operation a series of equidistant
saw-cuts for forming one side of each of the series of tenons or pins will be made at an
angle to the surfaces of the wood along the edge of the same. In fig. 4 some of the
said saw-cuts g¹ are represented by dotted lines as having been made in the piece of
wood g.
In order that the saw-cuts for the other side of the tenons or pins may be formed,
the frame b must be adjusted and clamped in the opposite angular position to that in
which it was first placed, viz., in the position shewn in fig. 5 and precisely the same
operation as that before described undergone, that is to say, a pencil or other mark
must first be made to indicate where the first saw-cut must be formed to constitute
the other side of the first tenon or pin and one of the gauge strips f adjusted similarly

page_text: to that herein before described, the cuts for completing the other sides for the
remaining tenons being also formed in a similar manner to that described. In fig. 5
some of the said saw cuts g² are represented as having been made in the piece of
wood g.
It will be obvious from the foregoing, that in order to alter the angle of the tenons
or pins the angle at which the frame is clamped must be altered and for making
tenons or pins of a different pitch the strips f must be removed and others used
having gauge-marks of the pitch required.
In order to remove the piece of wood between the tenons a chisel is employed,
93 fig. 7 representing one of such pieces and the dotted line 9 the cut to be made by
the said chisel.
For making the tenons or pins for blind dovetails we make use of the frame b but
we provide a stop upon the table e of the saw bench so as to prevent the saw-cuts from
going right through the wood. In this case, however, the saw-cuts forming the sides
of the tenons or pins cannot be formed the full depth by means of the circular saw on
account of its shape, so that the remainder of each cut has to be performed by means
of a chisel. This is illustrated clearly in fig. 9, the saw being shewn as having
attained its greatest depth in the wood j. jare dotted lines representing the
additional cuts to be made by the chisel in order to clear out the piece of wood
between the pins.
We sometimes make use of the stop k shewn in figs. 10 and 11, to assist the
operator in holding the wood in position. This stop consists of a narrow plate of
sheet metal k adjustably attached to a narrow strip of wood k², the said plate k¹ being
slightly wider than the wood 2 so as to form a sort of rabbet in which one end of the
piece of wood being operated upon bears, the lower edge of the plate k¹ serving to
engage with any one of the gauge marks f¹ as shewn clearly in dotted lines in fig. 3
and full lines in figs. 4 and 5. It will be obvious that the stop can engage with the
marks on either of the shelves b² or b³.
For cutting ordinary square grooves and tenons the frame b is set square with the
slot a¹ and the rest of the operation is the same as those hereinbefore described.
When cutting ordinary square grooves of a width not much greater than the
thickness of the saw we prefer to set the saw a little "out of truth so as to cause it
to "wobble" the width of the said grooves in order to cut the same at one operation,
as will be obvious.
In figs. 4 and 5 we have represented the tenons as having been formed with their
widest parts in the face of the wood adjacent to the frame b, this having been effected
by forming the saw-cuts g2 to the right-hand side of the saw-cuts g', but it will
be obvious that by forming the said saw-cuts to the left of the saw-cuts g¹ the widest
parts of the tenons can be formed in the other face of the wood.
The construction of the frame c is similar to that of the frame b except that it is
pivotted at to a bracket attached to the base a so as to be capable of adjustment
vertically in an angular position relatively to the surface of the base a a vertical
segmental slotted plate 12 being fixed to the said base to which the frame c can be
clamped by the thumb-screw m.
The operation of the frame c is similar to that of the frame b, with the exception
that after the first row of cuts n' fig. 6 is made, however, the piece of wood n is
turned end for end in order to make the other row of cuts n² as will be obvious. To
complete the mortises the pieces n³ between the saw-cuts, as shewn in fig. 8, are
removed by a chisel, the dotted lines n representing the cuts to be so made. As
shewn in fig. 6 the stop k can be used, if desired, in the operation just described in
the same manner as in the operation of making the grooves and tenons.
Instead of using a saw bench having an adjustable top as hereinbefore described, one
can he used having a fixed top and an adjustable saw, or having different sizes of saws
to be used therewith.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
(1) The use in combination with a circular saw bench, in which the saw and table
are relatively adjustable, of a frame for enabling a series of saw-cuts to be made to
form the sides of ordinary grooves and tenons, the said frame being capable of
horizontal angular adjustment relatively with the saw so as to enable tenons or pins
for dovetails to be formed substantially as described.
(2) The use in combination with a circular saw bench, in which the saw and table
are relatively adjustable, of a frame for enabling a series of saw-cuts to be made to
form the sides of mortises for dovetails, the said frame being capable of vertical
angular adjustment relatively to the table of the said saw bench so as to enable the
sides of mortises to be formed at any required angle, substantially as described.
(3) The use in combination with a circular saw bench, in which the saw and table
are relatively adjustable and having frames, such as those described in claims 1 and 2,
of a stop to be attached to the said table so as to prevent the saw passing through the
wood when cutting blind dovetails, substantially as described.
(4) The use in combination with either of the frames claimed in claims 1 and 2, of
a stop, such as that represented in figs. 10 and 11, substantially as, and for the
purposes, described.
(5) The improved appliances for cutting dovetails, grooves and tenons hereinbefore
described and illustrated in figs. to 6 and 10 and 11 of the accompanying
drawings.
1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.