AN IMPROVEMENT ON MACHINES FOR FORMING DOVETAIL JOINTS IN WOODWORK
Year: 1878

page_text: LETTERS PATENT to Lionel Varicas, of No. 24, Chancery Lane, in the County
of Middlesex, Patent Agent, for the Invention of "AN IMPROVEMENT ON
MACHINES FOR FORMING DOVETAIL JOINTS IN WOODWORK." A communi-
cation from abroad by William Howard Doane, of Cincinnati, County of
Hamilton and State of Ohio, United States of America.
Sealed the 14th February 1879, and dated the 9th October 1878.
COMPLETE SPECIFICATION filed by the said Lionel Varicas at the Office
of the Commissioners of Patents on the 9th October 1878.
LIONEL VARICAS, of No. 24, Chancery Lane, in the County of Middlesex, Patent
Agent. "AN IMPROVEMENT ON MACHINES FOR FORMING DOVETAIL JOINTS IN
WOODWORK." A communication from abroad by William Howard Doane, of
Cincinnati, County of Hamilton and State of Ohio, United States of America.
This Invention relates to that class of dovetailing machines which are capable of
forming matching dovetailed tenons and mortises on two pieces of lumber at one
operation, and in which the pieces of lumber are properly presented by a movable
carriage for cutting or shaping the edges.
One of the objects of this Invention is to so construct the machine that various
kinds of dovetail joints can be formed upon it, that is to say, dovetail joints of
which the tenons and mortises on the respective pieces of lumber may be either of
equal or different widths. This is accomplished by the use of two rotary cutting
tools, one for each of the two pieces of lumber to be operated upon, it being under-
stood that the combined sizes of the cutting tools used together must always equal
the combined width of an adjacent tenon and mortise, or in other words, the feed
of the carriage from one mortise to another; the relative sizes of the cutting tools
will determine the relative widths of the tenons and mortises. If the cutting tools
be of equal size the tenons and mortises will be of equal sizes; if of unequal sizes
[Price 6dı

page_text: the width of the tenons on one piece of lumber while corresponding to that of the
mortises on the other piece will differ from that of the tenons thereof.
Another object of this Invention is to so construct the machine that the dove-
tailed tenons may perfectly fit the dovetailed mortises of the joint, which requires
the rounding of the inner side of the tenons to fit the inner rounded end of the
mortises. To this end certain means are introduced, which cause the carriage to
advance with a compound movement, having the effect of advancing it with tho
boards in a curved path.
The relative arrangement of the parts will be such that the board on which the
rounded tenons are to be formed advances each time through the sweep of its
cutting tool, so that the latter will cut around one side of the tenon, and so effect
the required rounding thereof.
The Invention also consists of certain other details of construction set forth
specifically in some of the claims at the close of this Specification, and which, as
well as the features more at length alluded to above, will be clearly understood
from the following description:-
In the accompanying Drawings,-
Figure 1 is a perspective view of the improved machine with portions of the
carriage and clamping devices broken away to exhibit the location of the cutting
tools and their adjustable carriages.
Figure 2 is a transverse vertical section of the lumber carriage with the lumber
to be worked, representing also the relation of the cutting tools and their mandrels
to the carriage, and to the lumber secured therein.
Figure 3 represents the rear side of a portion of the carriage and its connection
with the slotted hand lever and the self-acting dog, which governs the advance
movements of the carriage.
Figure 4 represents a vertical section of a portion of the carriage and of the
hand lever, and exhibits the self-acting dog with its spiral spring, and the pin on
which it turns.
Figure 5 represents the vertically grooved gauging plate, and exhibits the
varying positions of the self-acting. dog in relation thereto during the operation of
the machino.
Figures 6 and 7 represent the ends of two detached pieces of lumber upon which
the dovetail joint has been formed.
Figure 8 is a inodification of certain means shown in Figure 3.
A, B, C, denote the lumber carriage provided with two eccentric clamping
rolls D, D', journaled in sliding boxes, so that they may be adjusted and set to
hold lumber of different thicknesses. Between the lumber carriage and the clamping
rolls I employ angle plates B₁, which work in the carriage frame and furnish
greater clamping surface for holding the lumber than could otherwise be had. The
eccentric rolls D, D', work in contact with the plates B¹, which are kept in contact
with their respective rolls by springs O¹.
The rear side of the carriage back A is provided with a vertical dovetailed rail·
which is fitted to slide in a corresponding dovetailed way upon the intermediate
travelling plate E. Lever F, hinged to the stud b on plate E has a slot c, through
which the pin d'attached to the carriage projects, as represented in Figure 3. By
means of this lever the carriage is moved vertically upon plate E, and horizontally
with plate E upon plate G, in which plate E is fitted to slide. Plate G is secured
to a table or frame H, I, K, in which the horizontal tool shafts are journaled.
Mounted upon the top of plate G is a plate L with a series of equidistant vertical
grooves T in its face, in which plays the guide c¹ of a pin o rigidly secured in the
fixed pin d of the carriage. This grooved plate governs the movements of the
carriage to and from the cutting tools, and the distance between its grooves deter-
mines the distance between the mortises.
The ribs V between grooves T of plate L are made with semicircular caps ¹
projecting beyond the surface of the ribs, and having curved recesses y in their
projecting under sides or edges, as represented in Figures 1 and 5, which recesses.
•

page_text: are engaged by the tooth t of a dog P during the operation of the machine to
govern the motion of the carriage in shifting it from one groove T to another.
Dog P is hung to turn on fixed pin o, and is acted upon by a spiral spring o¹,
which encircles pin o in a recess of pin d. The spring is fastened with one end to
pin o and with the other end to dog P, and should be held under tension.
The dog is located at such a distance from plate L that its tooth t may just clear
ribs V to swing into recesses y in the caps thereof.
The centers of the semicircular caps x1 are coincident with the centers of the
recesses y therein, and the distance between any two adjacent recesses y is exactly.
twice the distance between the axis of dog P and the centre of its tooth t.
The guide c¹ of pin o of the carriage fits the grooves T snugly, but moves smoothly
therein, and may be in the form of an antifriction roller.
As here designed the machine cuts tenons and mortises of the desired form only
in moving the carriage from groove to groove of plate L in one direction, so that
after forming a joint in two pieces of lumber the carriage has to be shifted to the
place of beginning before another joint can be formed. In thus shifting the carriage
it must be lifted high enough to carry dog P clear over the caps x¹. If no means
were provided against it the spring o¹ (unless dog P were held by hand) would
unwind every time the carriage was so shifted, and the attendant would be required
to give a few turns to the dog to re-wind its spring every time on beginning the
formation of a joint. As this would be tedious a means is provided to prevent the
unwinding of the spring at such times, and to hold the dog P in proper position to
begin its action in connection with recessed caps x of plate L. Figure 3 shows
one such means, consisting of a stop pin 5 so located on lever F that while it does
not interfere with the oscillations of dog. P as long as it operates with the recessed
caps, yet when lever F is turned up so high as to lift dog P above said caps the
pin 5 will stop dog P from turning, and thus prevent the unwinding of its spring,
as well as hold the dog in the proper position to again begin its action at the other
end of the plate.
Another and preferred means for this purpose is shewn in Figure 8, where a
spring pawl w is used to engage the dog P. The pawl is pivotted on lever F, and
has a downwardly projecting stem w¹, which abuts against the top of the carriage,
so as to hold pawl w out of engagement as long as dog P operates in connection
with caps x², but on lifting the lever F so high as to raise dog P clear of caps x1
the stem w moves away from the carriage and allows the pawl to engage and hold
dog P in the position shown.
The lumber l, m, is secured in the carriage, as shown in Figure 2, and held in
proper position for the action of the tools a, a', by means of the comb i, which
serves as a stop to prevent the lumber from being pushed too far into the carriage,
and by the clamping mechanism D, D¹; and plates B¹. The end of the piece of
lumber m rests against the upper edge of comb in proper position for the tool a
to cut that part of the joint shown in Figure 6, while the end of the piece is in
contact with the teeth of the comb, and held by clamp D and its plate B¹ in proper
relation to the tool a¹ for cutting the tenons, as shewn in Figure 7.
The two mandrels M, M, which respectively carry tools a, a¹, are seated in boxes
upon independently adjustable frames or carriages 3 and 4, and the pulleys upon
these mandrels are so arranged that they can be driven by two belts connecting
with a driving shaft.
The length of the tenons and corresponding depth of the mortises can be changed
at will by adjustments of the frames or carriages 3 and 4.
The attendant in using this machine will commence the work by bringing the
carriage into such a position that its guide c¹ will be in line with the first groove
(T) of plate L. The carriage is then pushed down by lever F, so that the cutters
will operate upon the pieces of lumber on it, cutting a dovetailed chamber or
mortise in the vertical piece m, and a dovetailed notch entirely through the edgo
of the horizontal piece 7.
The descent of the carriage is limited by a set screw F in lever F, striking the

page_text: top of plate E or any fixed part of the machine. By adjusting this set screw F¹
the length of the dovetailed mortise on piece m may be made to correspond exactly
to the thickness of the tenon on piece l.
As the guide c¹ enters the: top of the first groove in plate L dog P is released
(from stop pin 5 or pawl w, as the case may be), and at once turned by its spring o¹,
so that its tooth t will swing under the adjacent cap x¹. On raising the carriage
preparatory to moving it laterally to the next groove in plate L, tooth t engages
the recess y in cap a¹, and the dog and cap compel the guide c¹ to move in a semi-
circle to reach the next groove in plate L, so that the compound vertical and
horizontal motion of the carriage will have the effect of moving the lumber in a
semicircular path. When guide c¹ begins to give compound motion to the carriage
the piece of lumber m is already entirely out of the range of its cutter a, but the
piece of lumber is still in the range of its cutter a¹, so that during the compound
motion of the carriage said cutter a¹ will cut a rounded surface on the bottom of
the piece of lumber 7; in other words, the under sides of the tenons formed on the
piece of lumber 7 will be rounded to the shape shewn in Figure 7 to fit the rounded
inner end of the mortises in the piece of lumber m.
In moving the carriage from groove to groove of plate L the spring of dog P is
wound each time only to recoil and swing dog P under the next cap x² as soon as
the tooth t of the dog becomes released from the recess of the last preceding cap
by the downward movement of the carriage. The carriage is thus guided by its
guide c¹ both in its vertical motions and its movements from groove to groove of
plate L. After the last groove has been reached and made use of the carriage is
lifted high up and run back to the first groove of plate L ready to submit two fresh
pieces of lumber to the action of the cutters.
To prevent tool a' from breaking off or splitting the edges on the upper sides of
the tenons on the piece of lumber a block of wood may be secured upon said piece
of lumber, whereby the said edges will be preserved intact.
What I claim is as follows:-
1st. The combination of two independently working cutting tools with the
lumber carriage and its operating mechanism organized substantially as and for the
purpose described.
2nd. The curved and recessed heads ¹ of ribs V upon plate L in combination
with the reciprocating spring dog P, as and for the purpose described.
3rd. The reciprocating self-acting dog P provided with tooth t in combination
with guide c', lever F, and stop 5, as and for the purpose described.
4th. The combination of the clamping plates B' with their respective eccentric
rolls D, D', upon the lumber carriage A, B, C, as and for the purpose described.
In witness whereof, I, the said Lionel Varicas, have hereunto set my hand
and seal, this Ninth day of October, in the year of our Lord One thousand
eight hundred and seventy-eight.
LIONEL VARICAS. (L.S.)