Improvements in Machines for Mortising Timber.
Year: 1890

page_text: Date of Application, 19th Mar., 1890
Complete Specification Left, 4th July, 1890-Accepted, 9th Aug.,
1890
PROVISIONAL SPECIFICATION.
Improvements in Machines for Mortising Timber.
We THOMAS LEES and RALPH LEES Engineers Park Foundry, Hollinwood, near
Oldham, do hereby declare the nature of this invention to be as follows:-
Improvements in Machines for Mortising Timber, consisting of a revolving shaft
and crank and a combination of adjustable levers and balance weight to give variable
reciprocating motion to the chisel operating upon the timber.
Dated this 18th day of March 1890.
THOMAS LEES.
RALPH LEES.
COMPLETE SPECIFICATION.
Improvements in Machines for Morticing Timber.
We THOMAS LEES and RALPH LEES, Engineers, Park Foundry, Hollinwood near
Oldham do hereby declare the nature of our invention for "IMPROVEMENTS IN
MACHINES FOR MORTICING TIMBER" and in what manner the same is to be performed
to be particularly described and ascertained in and by the following statement
and accompanying drawings:-
--
Our said invention relates to an improved construction of morticing machines for
timber in which the device carrying the chisel derives motion from a rotating shaft
placed below the point of action of the chisel and in which a system of links and
levers intermediate between the driving shaft and the chisel holder is provided for the
purpose of transmitting a reciprocating motion to the chisei and for readily varying
its stroke while the machine is in action.
In order that our said invention may be more readily understood we will at once
proceed to describe the same by reference to the accompanying drawings in all the
figures of which the same letters refer to the same parts.
Figure 1 is a vertical elevation partly in section of an underdriven morticing
machine constructed in accordance with our said invention.
We place the first motion shaft A as low as possible and below the point of action
of the tool and in this manner obtain greater steadiness and freedom from vibration
than has hitherto been the case in morticing machines driven by power. The placing
of the driving shaft in such a position necessitates the arrangement of mechanism
shown in the drawing for driving and regulating the stroke of the chisel.
Secured to the first motion shaft of the machine is a crank A', preferably of a disc
form. This crank imparts oscillatory motion to the rocking shaft D by means of a
jointed connecting rod B B and a fever C secured to the rocking shalt D. To the
rocking shaft D is also secured a lever E at the end of which is jointed one end of a
link F. The other end of the link is hinged to the slide G carrying the morticing
chisel G. By means of the parts just described a vertical reciprocating motion is
imparted to the chisel G₁ by the rotation of the shaft A.
In order to vary the stroke that is to say the amount of vertical motion of the
chisel we employ the system of links and levers shown at H I K L.
H is a treadle lover pivoted at H and connected at one end H' by means of a link I
to one arm K of a bell crank lever oscillating about the centre K on a fixed part of
the machine. The other arm K³ of the bell crank lever carries a stud K on which
works one extremity of the radius rod I.
The other end of the radius rod L fits on the joint pin B2 of the jointed connecting
rod. In Fig. 1 the treadle lever His shown in the position it occupies when
depressed to its utmost extent and the other levers and links are shown in full lines in

page_text: the positions they occupy when the pin of the crank A' is at its highest point. The
slide G carrying the chisel is then in its extreme lowest position and if the crank
pin A now revolves about its centro the rocking shaft D will receive its maximum
Oscillation and the slide G will therefore receive its maximum stroke. The jointed
connecting rod B B becomes under the above described circumstances practically
rigid since the path of the joint pin 132 is constrained by the radius rod L to follow an
approximately vertical path. The dotted lines in Fig. 1 show the position of the
parts when the crank pin is at its lowest point. The dotted ares in all the figures
indicate the lines of movement of the pivots of the various joints.
A balance weight M is suspended from the end of the treadle lever in order that
when the pressure of the foot is released the end H' may descend and cause the bell
crank lever to assume the position shown in Fig. 2 in which only the essential
features of our invention are shown. In this figure the full lines as in the case of
Fig. 1 represent the position of the parts when the crank pin is at the highest point
of its course. When the treadle lever is in the position shown in Fig. 2 the joint
pin B2 is constrained to an approximately horizontal path by the radius rod L which
is now parallel to the part B of the jointed connecting rod and the revolution of the
crank pin will merely impart a pendulous motion about its centre to the upper
member B of the jointed connecting rod. Hence no direct thrust can be exercised
on the lever and the rocking shaft. D will not oscillate nor will the slide G move.
In this figure the dotted lines indicate the position the jointed connecting rod assumes
when the crank pin is at its lowest point.
The traverse of the slide G depends entirely on the extent of the oscillations of the
rocking shaft D which in turn is governed by the amount of constraint exercised by
the radius rod L on the joint pin 13. Therefore by depressing the treadle lever H so
as to cause the centre K of the radius rod L to assume positions intermediate between
the extreme positions shown in Figs. 1 and 2 the stroke of the machine may be varied
at will.
Such an intermediate position is illustrated by Fig. 3 the full lines of which again
represent the parts when the crank pin is at the top while the dotted lines show
the relative positions of the parts when the crank pin is at the bottom. With the
centre K of the radius rod L in the position shown in Fig. 3 the motion of the
joint pin B2 of the connecting rod has both horizontal and vertical components
and a movement corresponding to the vertical traverse of the joint pin B is imparted
to the lever C.
The position of the chisel holder N may be varied on the slide to suit timber
of different depths and the usual appliances for holding the timber and feeding it
forward while being operated upon are provided as is well understood.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is―
1. In a morticing machine the use of a crank placed below the point of action
of the chisel substantially as and for the purpose hereinbefore described and set
forth.
2. In a morticing machine the use of a crank placed below the point of action of
the chisel with means for actuating the chisel therefrom substantially as and for the
purpose herein before described and set forth.
3. In a morticing machine the use arrangement and combination of levers, links
and a rocking shaft for imparting a variable stroke to the slide carrying the chisel
driven from a crank shaft placed below the point of action of the chisel and regulated
by a treadle substantially as herein before described and shown.
Dated this 3rd day of July 1890.
JULIUS ALLMANN & Co.,
70, Deansgate, Manchester, Agents for the Applicants.