Improvements in Machines for Forming Dovetails in Woodwork.
Year: 1893

page_text: Date of Application, 10th May, 1893
Complete Specification Left, 10th Feb., 1894-Accepted, 10th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in Machines for Forming Dovetails in Woodwork.
We, ANDREW KERR, ROBERT KERR, WILLIAM KERR and JOHN KERR of
the Firm of Messrs. Robert Kerr and Sons, Glengarnock, Ayrshire, and ANDREW
MCFADYEN of 32 Clarendon Street, Partick Lanarkshire, both in Scotland,
Engineers, do hereby declare the nature of this invention to be as follows:-
Our invention relates to improvements in that class of woodwork dovetailing
machines wherein the two wooden boards to be dovetailed are held in a frame
which is moved and presents the wood to the stationary revolving cutter which
forms the dovetailed pins or tennons and spaces or mortices in both boards at one
operation; and whereby superior work, smaller pins and spaces, and greater
facilities for setting machine to cut different sizes of work, are effected than in
machines as heretofore constructed.
The improvements relate to the mechanism for moving the boards carrying
frame or slides, which said mechanism works between the ordinary actuating screw
and rigid comb or rack of the machine. The mechanism consists of a pinion
gearing into and actuated by the ordinary work-wheel wrought by the revolving
screw. From the pinion projects an adjustable excentric pin which reciprocates a
connecting rod having an adjustable set-pin therein. The rod and worm wheel has
or may have pins projecting therefrom which take into the comb similarly to those
of existing machines, for regulating the space moved.
Dated this 9th day of May 1893.
D. F. MASON, C.E.,
Glasgow, Patent Agent.
COMPLETE SPECIFICATION.
Improvements in Machines for Forming Dovetails in Woodwork.
We, ANDREW KERR, ROBERT KERR, WILLIAM KERR and JOHN KERR of
the Firm of Messrs. Robert Kerr and Sons, Glengarnock, Ayrshire, and ANDREW
MCFADYEN of 32 Clarendon Street Partick, Lanarkshire, both in Scotland
Engineers 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 :--
Our invention relates to improvements in that class of woodwork dovetailing
machines wherein the two wooden boards to be dovetailed are held in a frame
which is moved and presents the wood to the stationary revolving cutter, which
forms the dovetailed pins or tennons and spaces, or mortices in both boards at one
operation and whereby superior work, smaller pins and spaces, and greater
facilities for setting machine to cut different sizes of work may be made or effected,
than in machines as heretofore constructed which cut the inner ends of the pins or
tennons and spaces or mortices rounded so as to accurately fit each other without
any further finishing or dressing.
And in order that our said invention may be properly understood, we have
appended the annexed drawings, illustrating a machine as constructed in accordance
with our invention.
Fig. 1 of the drawings is a side elevation of the machine; Fig. 2 is a plan

page_text: thereof; and Fig. 3 illustrates the configuration of the work effected on the wood
or other material operated on.
The frame a of the machine has fixed thereon the dovetailed bed or shears e on
which is fitted the correspondingly dovetailed sliding bed f', which is capable
of sliding longitudinally along said shears e. On the bed is fitted the carrier
plate by means of dovetailed or other slides, so as to be again capable of sliding
transversely, or to and from the cutter g. On the plate fis fixed the frame b,
provided with screw clamps d, c for fixing the boards respectively horizontally and
vertically on and to the carrier plate and frame b; which said plate and frame
may be termed the carriage of the machine. To the main frame a is rigidly fixed
the comb or toothed bar having the comb or teeth i formed thereon. In
bearings n fixed to the frame a is fitted the revolving screw shaft n; the screwed
part of said rod being indicated on Fig. 2 by dotted lines. Said rod has fixed on
end thereof the pulley m which is revolved by the belt m¹ working over it and the
pulley p fixed on reversing shaft 9 supported in bearings ql fixed to frame a.
The shaft 9 on inner end has fixed thereon a bevel pinion qt which is worked in
the usual well known manner by the bevel wheels o actuated through a usual
reversing clutch on main driving shaft r supported in bearings 11 fixed to frame a,
and revolved by the drive pulley through the usual motive power belt. On the
shaft is fixed the speed pulleys which drives the belt s revolving the pulley
fixed on cutter shaft & supported in bearings t¹ fixed on a plate capable of being
raised and lowered in guide slides u by means of the band wheel on spindle &¹
which is stepped at bottom on a foot piece fixed on frame a, and screwed on top
part which works in socket ull fixed to last aforesaid plate, and so thereby the
cutter g may be raised or lowered.
All the several parts of the machine hereinbefore set forth are or may be
constructed and operated similarly to corresponding parts of analogous machines,
being common thereto.
An especial object of our invention is to cause the carriage to move with a
compound motion at a certain point, so as to move said carriage with a curved path
so as to cut the inner ends, 4 as shown at Fig. 3 of the pins or tennons of the one
board rounded, so that when the pins are reversed; to correspond to and fit
accurately against the inner edges 5 of the spaces or mortices of the other board.
This is effected by the mechanism hereinafter described.
Into the spiral screw m fits the teeth of the worm-wheel v which teeth also fit
between those of the pinion w, both wheels v and w being thereby actuated by the
screw n. The said wheels v, w, are mounted on a bracket a fixed to, and sliding
longitudinally with the bed f. In the outer projecting arm of bracket a slides
the outer end of rod y' which is formed with a swelled part.in which is formed the
slot y; the bottom part being capable of being adjusted on, and relative to (by the
adjusting screw-pin 2) the bracket z' which is bolted to the carriage plate f. From
the back of bracket z projects a piu 6 fixed thereon which slides between the
teeth i of comb and keeps the bracket z' and carriage from moving longitudinally
at desired time: The rod y' which transversely reciprocates the carriage fis
actuated by the. pin 7 working in the slot y. The pin 7 is fitted in. a groove, in
face of disc 8, so as to be eccentrically adjustable therein. to suit the desired length
of cut in material operated on; the said disc being fixed on a spindle-fitted to, and
revolved by the pinion to all supported by the bracket a. In between the lower
part of teeth i works the eccentric pin 9, fixed in and revolving with the disc 91
fixed on a spindle which fits through the bracket and. is fitted to and revolves
with the wheel v. Said disc and spindle is or may be made readily taken out and
replaced with another differently spaced pin 9 to suit another size of tenon and
mortice as may be desired to be cut. The pin 9 at given times bears against the
rigid teeth and thus moves the carriage longitudinally while said carriage is also
being moved transversely by the pin 7, thus giving the compound motion to the
carriage, which causes the boards to be presented to the cutter in a circular path
so as to cut the tenons with the rounded edge 4.

page_text: On Figure 3 the representation is a view looking up from below of the horizonta
board 12 and vertical board 13 as they would appear when set together and being
cut, the plain and dotted lines respectively representing the bottom and top edges
of cut corresponding to the dovetailed shaped cutter g.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is
1st. The arrangement of mechanism constituting the machine as hereinbefore set
forth and shown.
brackets &
2nd. The mechanism consisting of the two toothed wheels v, w;
and '; rod y'; discs 8, 9¹; pins 7 and 9 all organized, arranged, constructed,
combined and operating, substantially as set forth and shown.
3rd. The application and use of an eccentric pin and disc 9, 9' having a spindle
capable of easy removal and replacing, substantially as and for the purpose set
forth.
DLL:- och J.- 1904