IMPROVEMENTS IN 'DOVETAILING MACHINES."
Year: 1878

page_text: A
LETTERS PATENT to Martin Benson, of No. 9, Southampton Buildings, London,
for the Invention of "IMPROVEMENTS IN 'DOVETAILING MACHINES.""
communication from abroad by William Howard Doane, of Cincinnati, Ohio,
United States of North America.
Sealed the 27th June 1879, and dated the 31st December 1878.
COMPLETE SPECIFICATION filed by the said Martin Benson at the Office
"1
of the Commissioners of Patents on the 31st December 1878.
MARTIN BENSON, of No. 9, Southampton Buildings, London. IMPROVEMENTS
IN DOVETAILING MACHINES.'" A communication from abroad by William Howard
Doane, of Cincinnati, Ohio, United States of North America.
My Invention relates to that class of machines which are adapted for forming
dovetailed joints in wood work by means of rotary cutters, and more especially to
such machines as are constructed to automatically round one side of the dovetailed
tenons on one of the two boards or pieces of lumber operated upon so that said
rounded side of the tenons may make a close fitting joint with the necessarily
rounded end of the dovetailed mortises in the other board or piece of lumber.
My Invention consists in the construction and arrangement of devices for auto-
matically traversing the lumber carriage across the rotary cutter, also in so
constructing the machine that joints may be formed during both the forward and
backward movement of the carriage, also in the construction and mounting of the
cutter and in the construction and combination of other parts, as will be hereinafter
more fully set forth and pointed out specifically in the claims.
In the annexed Drawings Fig. 1, Sheet 1, is a front elevation of a dovetailing
machine embodying my Invention.
Fig. 2 is a rear elevation of the same.
Fig. 3 is a transverse vertical section thereof on the line x, x, Fig. 1.
Ti A to Shoot 2 are detail viases of different parts of the machine

page_text: Figs. 9 to 16 are detail views shewing the construction and mode of mounting of
the cutter.
A represents the frame of my machine; B is the lumber carriage, provided with
the clamping rollers C, C, operating on angles or plates C¹, C¹, for holding the two
pieces of lumber to be operated upon, one piece being held in a horizontal and the
other in a vertical position.
The carriage B is movable up and down in dovetailed guides on an intermediate
travelling plate D, and this travelling plate is movable horizontally upon suitable
ways on a saddle E attached to the main frame of the machine.
The carriage B is provided with a slotted yoke F which may be adjusted up and
down by means of a set screw a, or in any other suitable manner for the purpose of
regulating the up and down movements of the carriage. This yoke F is provided
with a fixed pin or guide b, entering the vertical grooves x between the ribs x¹ on
the fixed plate G, said guide pin fitting the grooves so snugly that it has no lateral
play therein. The ribs x¹ extend below the lower edge of plate G, forming a comb.
The vertical side of the lumber carriage is provided with the comb d to allow the
cutting tool to pass through between the teeth thereof into the lumber. The carriage
is moved automatically by the following means:-Upon the travelling plate Dis
attached a bearing for a journal e of a worm gear H, which meshes with a worm
screw I arranged in bearings back of and parallel with the plate E. The journal e
is at its forward end provided with a crank pin f having a cam h on its end, which
cam enters the slot in the yoke F of the lumber carriage, while the crank pin Fat
times enters between the ribs x' of plate G, its throw being equal to the distance
between two adjacent grooves x.
The effect of this mechanism on the lumber carriage is modified by the ribbed
plate G and the fixed guide pin b on the yoke F, and the conjoined operation of all
this set of devices may be set forth briefly thus: Take the position of the
parts shewm in Fig. 1, the carriage having arrived at the lowest point
of its descent, and consequently the cutting of two corresponding mortises
having just been completed. The yoke F of the lumber carriage rests on the
flat side of cam h, the crank pin is below and free from the ribs a¹, while the
guide pin b of the yoke F is between two ribs x¹ of plate G. Now let the journal
e be turned in the direction of the arrow, see Fig. 1, cam h will at once operate on
yoke F and begin to elevate the carriage whereby guide pin b is also elevated.
By the time guide pin b reaches the upper extremity of the groove x in which it
travels for the time being crank pin f enters the next adjacent groove x. At this
point of time this carriage will have ascended so far as to have withdrawn the
vertical piece of lumber entirely and the horizontal piece of lumber partly from
rotary cutter W. As journal e continues to turn its crank pin f becomes engaged
between the ribs of the groove x adjacent to the groove which guide pin b is just
leaving at the other end, and a compound movement in now imparted to the
lumber carriage, viz., cam h continues to elevate it while crank pin f (which in con-
sequence of its engagement in the plate or rack G causes a traversing or travelling
motion of journal e) draws it in a horizontal direction. The throw of the crank pin f
is exactly the same as the throw of the cam h, and the cain is so formed that this
combined action of the crank pin and cam results in moving the lumber carriage in
the arc of a circle the centre of which is in a plane midway between the groove x
just left by guide pin b and the adjacent groove between the downwardly projecting
ribs a¹ of which crank pin f is operating. The axis of the journal e is on the line
of the lower ends of ribs x', so that the crank pin f makes one half of a revolution
from the time of entering between to the time of escaping from any two ribs x².
Hence in moving the lumber carriage from groove to groove of the plate G, the
traverse of any point of such carriage is semicircular, in consequence of which
rotary cutter W will cut a semicircular rounding upon the lower side of the horizontal
piece of lumber in shifting the carriage from groove to groove; or in other words, one
side of the tenons of the horizontal piece of lumber will be rounded to fit the
rounded inner end of the mortises cut in the vertical piece of lumber.

page_text: In the lower part of the frame A is a horizontal shaft J, to which motion is com-
municated by belt or otherwise from the line shaft, and upon this shaft J are
secured two bevelled friction gears K, K¹. Between these friction gears is a single
friction gear L secured upon a shaft M which has its bearings in a swinging or
pivoted box N so that the gear L may be thrown in contact with either of the
gears K and K¹, and driven thereby alternately in one direction and the other.
Upon the other end of the shaft M is a pulley connected by belt O with a pulley
on the end of screw I.
The pivoted box N is provided with an arm which is connected by a rod i with
the lower end of the pivoted shipper lever P for swinging the box N. Below tho
plate E is a rod R running parallel therewith and provided near each end with an
adjustable collar or tappet m. The lever P passes through an eye of a projection
on the rod R, as shewn fully in Fig. 6, and as the lever is moved one way or the
other, it moves the rod, and vice versa. The shipper lever also passes up through a
loop on the frame and is firmly clamped to the loop bar by a spring n with sufficient
friction to overbalance the tendency of the friction gears K or K¹ to move the fric-
tion gear L out of frictional contact when driven by either of them.
Now as the carriage moves to one end it strikes the tappet m, moving the rod R
and also the shipper lever P, thereby disengaging the friction gears so as to stop
the feed. The operator then removes the two finished pieces of lumber and puts in
two fresh pieces. He then slips the lever P still further than the lumber carriage
shipped it so as to force gear L into frictional contact with the other friction gear
on shaft J. This again starts the operation of the machine, the traverse of the
carriage being now in a reverse direction, however; after rounding the last tenon the
carriage again stops the machine by striking the tappet on the other end of the
rod R, when fresh pieces are again put in and the feed reversed again. The car-
riage always stops at the extreme upward throw of the crank and at the extreme
right or left hand end of the series of grooves x of plate or rack G.
By this construction of devices joints are formed both during the forward and the
backward movement of the carriage, whereas in machines of this character it has
heretofore been necessary to return the carriage by hand back to the starting point,
and joints could only be formed while the carriage was travelling in one direction.
From a pulley on the shaft J a belt S connects with a pulley on the mandrel V
which carries or drives the bit or cutting tool W. The mandrel V is bored out
eccentrically from the end to receive the shank A' of the cutter W, which shank is
also turned eccentric to the end of the cutter. On account of this double eccentricity
the cutter can easily be adjusted to cut larger or smaller as desired by simply
turning the cutter in the mandrel, and the cutter is held in any position by a set
screw p or other suitable means.
Instead of having the hole in the mandrel bored eccentric it may be bored con-
centric, and an eccentric thimble B₁ inserted therein to match the eccentric shank
of the cutter. The use of a concentrically bored mandrel provided with an eccen-
trically bored thimble for the reception of the eccentrically shanked cutter possesses
several advantages over the eccentrically bored mandrel. For instance, this part of
my Invention can in that form be readily applied to existing machines. Again in
case the mandrel were sprung by overstrain, and required to be trued up in a lathe,
it could be much more easily centered than an eccentrically bored mandrel.
This feature of eccentricity of the cutter and mandrel chuck is applicable to routing
and other cutting tools.
Having now described the nature and construction of my Invention, what I
claim is,―
1st. In a dovetailing machine a lumber carriage operating automatically up and
down and backward and forward by means of a reversible feed device whereby
joints may be formed during both the forward and backward movement, the whole
constructed substantially as herein set forth.
2nd. The combination, substantially as before set forth, of the lumber carriage

page_text: provided with a guide pin, the rack for controlling the movements of the carriage,
and the travelling connected cam and crank pin for moving the carriage.
3rd. The combination, substantially as before set forth, of the lumber carriage
provided with a guide pin, the rack for controlling the movements of the carriage,
the travelling connected cam and crank pin for moving the carriage, and the rever-
sible feed gearing.
4th. The combination of a mandrel having an eccentric tool socket and a cutting
tool provided with an eccentric shank, as herein set forth.
5th. The combination of a concentrically bored mandrel, an eccentric sleeve or
thimble inserted therein, and a cutting tool provided with an eccentric shank, sub-
stantially as herein set forth.
In witness whereof, I, the said Martin Benson, have hereunto set my hand
and seal, this 31st day of December, in the year of our Lord 1878.
MARTIN BENSON. (L.S.)