IMPROVEMENTS IN MACHINES FOR MORTISING WOOD a
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office of
the Commissioners of Patents on the 22nd August 1882. Communicated
to him from abroad by Jean Baptiste Alexandre of Paris in the Republic of
France.
"
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN MACHINES FOR MORTISING WOOD a communi-
cation to me from abroad by Jean Baptiste Alexandre of Paris in the Republic
of France
This Invention relates to machines for mortising wood and consists essentially
in the addition to such machines of mechanical arrangements or means for the
penetration of the wood by the tool which effects the mortising in an automatic
manner without liability to breakage.
In carrying out this Invention which is applicable to mortising machines in
which a rotating tool is employed capable of moving longitudinally or in the
direction of its axis for the purpose of enabling it to be advanced as required the
arm which effects the longitudinal motion of the shaft carrying the rotating tool is
operated automatically by the machine in place of being worked by hand as here-
tofore practised. For this purpose the said arm is hinged to a sliding bar and is
provided at its extremity with a steel plate which engages with a screw thread
formed on a shaft working in bearings and carrying a cone pulley at one
extremity.
By means of this pulley a relatively slow motion is imparted to the screw shaft
and transmitted to the arm which is thus caused to move forward the shaft
carrying the rotating tool with great regularity without the assistance of the work-
man who is thus enabled to attend to and work the carrier continuously and
without waste of time
The traversing motion of the carrier is limited by means of two projections one
of which is immoveably fixed to the carrier whilst the other is capable of being
adjusted according to the length of the mortice
To the bed of the carrier are bolted two supports carrying a rock shaft capable
of being secured in any desired position by means of a hand lever keyed on the
said shaft and engaging in a notched segment-This shaft carries two sleeves pro-
vided with stops corresponding to the projections on the carrier and connected
D

page_text: with counterweights which sleeves are capable of describing an arc the length of
which is limited by recesses working over fixed stops or projections formed on the
shaft.
The distance between the two stops on the sleeves is exactly the same as that
between the centre of the rotating tool carrying shaft and the centre of a recipro-
cating tool hereinafter described which is employed to cut the angles of the mortice
-The counterweight connected to one of the stops is also connected by a chain to
a sliding bar carrying the arm hereinbefore referred to for advancing the rotating
tool and the counterweight on the other stop is similarly connected to the shaft of
the reciprocating tool.
The counterweights cause the stops on the sleeves to have a constant tendency to
turn in one direction but when the tools do not move forward the stops are held
back by the chains and clear the projections on the carrier-Suppose for example
that it is desired to cut a certain quantity of mortices of the same dimensions―A
register mark is made upon the carrier in a given position and the piece of wood
to be mortised being provided with a corresponding mark is placed upon the carrier
and secured in the proper position-A stop placed upon the carrier is adjusted in
such a manner that when this stop is brought in contact with a projection on the
bed the place for the mortise is placed exactly in the required position relatively to
the rotating tool so that by simply moving the carrier to the end of its stroke the
proper position of the first hole is ensured without any further adjustment—The
rotating tool is then brought into action and caused to form the two ends of the
mortice, the length of the mortice corresponding to the position of the adjustable
stop on the carrier.
When this preliminary operation is concluded the plate on the end of the lever
is caused to engage with the screw and the shaft carrying the rotating tool is then
moved forwards by the action of this screw so that the workman is simply required
to move the carrier to and fro to an extent controlled by the stop on one of the
sleeves herein before described which stop comes in contact with the opposite sides
of the projections on the carrier alternately.
When the mortice is thus formed the jointed arm is disconnected from the screw
shaft and the shaft carrying the rotating tool is then enabled to be moved back by
means of the said arm and by means of the chain causes the stop to describe an arc
of a circle and move out of the path of the projections on the carrier.
The carrier is then moved into such a position as to bring the mortice opposite
the reciprocating tool-The corners or angles of the mortice are then cut out with
precision by working the reciprocating tool by means of a lever and moving the
carrier to and fro to an extent controlled by the position of the projections thereon
which now come in contact with opposite sides of the other stop.
When it is desired to form mortices of different sizes in the same piece of wood
the adjustable projection on the carrier is provided with an adjusting screw the
extremity of which is placed at the desired distance from the fixed projection and
in this case the shaft carrying the stops is caused to rotate by means of a small
hand lover which is then caused to engage in the lower notch in the segment so as
to bring the stop in the path of the end of the adjusting screw on the carrier-
The operation then proceeds as hereinbefore described.
When, as is frequently the case it is not required to cut the mortice through to
the other side of the wood the depth of the mortice may be adjusted with precision
by means of a slotted plate screwed to the support of the sliding bar and a stud or
bolt working in the slot in the plate and acting as a stop-By adjusting the posi-
tion of this bolt or stud so that it comes in contact with the extremity of the guide
bar the depth of the mortice can be regulated at pleasure.
When it is desired to cut the mortice through the whole, thickness of the wood
the slotted plate must be turned round on its point of support so as to move the
adjustable stop out of the path of the extremity of the bar-This can be effected
with great celerity and without interfering with the progress of the work.
In order to avoid the tearing action produced at the sides of the mortice by the

page_text: passage of the rectangular chisel or tool during the operation of cutting out the
corners a tool is employed provided with three cutting edges so arranged at
different distances from the axial line that the wood is removed in layers the first
edge removing one third of the depth of wood to be cut away the second removing
5 another third and being followed by the third edge which finishes the work to the
required depth.
The Invention is not limited to the precise mechanical arrangements hereinbefore
described as the means of carrying out the same