Improvements in Mitre Clamps.
Year: 1889

page_text: Date of Application, 17th Oct., 1889
Complete Specification Left, 10th July, 1890-Accepted, 16th Aug., 1890
PROVIDIONAL DIMOITIVATION.
Improvements in Mitre Clamps.
A communication from RALPH DUNCAN STEWART, of Onehunga, Auckland, School-
master, and DAVID FOSTER, Carpenter, of Auckland, aforesaid, both in New
Zealand.
I, FREDERICK CHARLES STEWART of 10 Sudbourne Road, Brixton, in the County
of Surrey, Agent, do hereby declare the nature of this invention to be as follows:
This invention relates to clamps applicable particularly for holding together
the mitred joints of picture frames and the like, during the setting of the glue
used to secure the joints. In carrying out the invention we prefer to proceed as
follows:-
For each corner is provided a clamp, preferably a casting, with clips, ears or
equivalent adapted to fit over the two sides of the corner upon one face of which it is
placed. The ears are preferably made a little off the square so as to counteract the
tendency of the sides of the frame to close in; the clamps may be provided with a
number of holes or fastening devices from which the cords or equivalent to be next
described extend. These clamps are connected in pairs by a cord, chain or equiva-
lent, each of the cords being movably connected, as by a loop, pulley or equivalent
with one of a pair of levers, which when in use remain centrally in the frame. This
pair of levers consists of a pair of rods, or bars jointed or pivoted at one end and
provided with handles at the other; they also have the loops, pulleys or equivalent,
already mentioned, and some means of holding them when drawn together for the
purpose of applying the tension.
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Many different devices may be adopted for holding the levers together, as for
example a simple perforated strip pivoted upon one lever and a pin upon the other
fitting into the perforations of the strip; quadrantal rack on one lever, and a spring
pawl upon the other; a chain on one lever and hook or pin upon the other; or a
variety of other different devices.
In using this apparatus the clamps are placed one over each corner the cord or
chain from each pair passing round its connection with its respective lever; all that is
required then to apply the tension is to draw the free ends of the levers together and
clamp them as already explained. This has the effect of applying the strain upon all
the corners in the manner required. If desired the cords might be connected at more
than one point with the levers, but generally speaking one point is found to be
sufficient; also a different arrangement of levers to that described might be employed
without departing from the spirit of the invention. Or the levers may be dispensed
with and a different mechanism such as two hooks nuts and a right and left handed
screw or a roller to wind up cords connecting the two main cords may be substituted
for the levers.
If desired the cords may proceed from only one side of the clamps or from both sides
so as to pass on either or both sides of the frame, and pulleys may be employed with
these clamps if desired.
It will be understood that this invention may be applied to other objects' besides
picture frames.
Dated this 17th day of October 1889.

page_text: Improvements in Mitre Clamps.
A communication from RALPH DUNCAN STEWART, Schoolmaster, of Onchunga,
Auckland, and DAVID FOSTER, Carpenter, of Auckland, aforesaid, both in New
Zealand.
I, FREDERICK CHARLES STEWART of 10 Sudbourne Road, Brixton, in the County
of Surrey, Agent, 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 :-
This invention relates to clamps applicable particularly for holding together the
mitred joints of picture frames and the like and mitre joints generally, during the
setting of the glue used to secure the joints. In carrying out the invention I prefer
to proceed as follows:-
For each corner is provided a clamp preferably a casting with clips, ears, or
equivalent, adapted to fit over the two sides of the corner upon one face of which it is
placed. The ears are preferably made a little off the square so as to counteract
the tendency of the sides of the frame to close in ; the clamps may be provided with
a number of holes or fastening devices from which the cords or equivalent to be next
described extend. These clamps are connected in pairs by a cord, chain or equivalent,
each of the cords being movably connected, as by a loop, pulley, or equivalent,
with one of a pair of levers, which when in use remain centrally in the frame. This
pair of levers consists of a pair of rods, or bars, jointed or pivoted at one end and
provided with handles at the other; they also have the loops, pulleys or equivalent,
already mentioned, and some means of holding them when drawn together for the
purpose of applying the tension.
Many different devices may be adopted for holding the levers together, as for
example a simple perforated strip pivoted upon one lever and a pin upon the other
fitting into the perforations of the strip; quadrantal rack on one lever, and a spring
pawl upon the other; a chain upon one lever and hook or pin upon the other; a
simple clamp pivoted upon one lever and embracing the other, or a variety of
other devices.
In using this apparatus the clamps are placed one over each corner the cord or
chain from each pair passing round its connection with its respective lever; all that
is required then to apply the tension is to draw the free ends of the levers together
and clamp them as already explained. This bas the effect of applying the strain upon
all the corners in the manner required. If desired the cords might be connected at
more than one point with the levers but generally speaking one point is found to be
sufficient; also a different arrangement of levers to that described might be employed
without departing from the spirit of the invention. Or the levers may be dispensed
with and a different mechanism such as two hooks, nuts and a right and left
handed screw or a roller to wind up cords connecting the two main cords may be
.substituted for the levers.
The cords may proceed from only one side of the clamps or from both sides so as to
pass on either or both sides of the frame, and pulleys may be employed with these
clamps if desired.
It will be understood that this invention may be applied to other objects besides
picture frames.
In the accompanying drawings Fig. 1 is a general view of the apparatus in use,
Fig. 2 is a detail of one of the clamps, and Fig. 3 a view of a modified clamp.
A represents the frame to be held and B are the clamps. C are the cords or
equivalent each connecting two clamps with one of the levers D as will be clearly seen
from the drawing, in which each cord is shown as a single piece carried through a
hole B (of which there may for convenience be more than one) in each clamp and
round a pulley D¹ on the lever the two ends being connected by knotting one end in
a loop of the other end so that the length of the cord may be varied according to need. It

page_text: is evident however that the arrangement and connection of the cords C can be greatly
varied without altering the invention, and that rods adjustable for length could easily
be substituted for the cords.
The levers D are jointed together by one or more links E at one end, or by other
convenient means, and at the other terminate in handles D2 and one of them carries
a rack F pivoted to it at F¹ while the other lever carries a pin G adapted to engage
with the rack when necessary.
As already explained however any other suitable
locking device may be employed.
The pulleys D¹ may be carried in brackets D³ or in any other convenient manner.
The construction of the clamps B will be well understood from the drawings, the
clips or ears B2 serving to grip the frame and being preferably set at rather less than
a right angle to the plate B so as to counteract the tendency of the clamp to pull the
frame pieces over where the cords are applied upon one side of the frame only. If
the cords were used on both sides of the frame each clamp would have two plates B
with the ears B2 connecting them and the ears would in such case form a right angle
with the plates; or a pin could be placed through both plates and a pulley placed
upon it or the cord passed round it and thus a single cord would give a central
pull, this latter arrangement being illustrated in Fig. 3. However I find that
the device works well with the cords upon one side of the frame only and I generally
use that arrangement.
The operation is as follows:-
The pieces of the frame are glued and put together, or if glue be not used the
pieces are simply put together and the clamps placed over the corners as shown in
Fig. 1; the cords C and levers D occupying then somewhat the positions indicated in
dotted lines in the drawing. The handles D2 are then brought together or as nearly
together as may be necessary to give the requisite tension and secured by the rack F
and pin G or otherwise as above explained; the pieces of the frame are thus
securely held together while the glue dries or while they are screwed or fastened
together. The apparatus is then undone and removed and is ready for fixing another
frame.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I declare that what I claim is
1. In a frame fastening device the combination with corner clamps such as B
of levers such as D flexibly connected with the clamps upon which they pull
when drawn together substantially as described and illustrated in the accompanying
drawings.
2. In a frame fastening device the combination with clamps such as B and levers
such as D of cords or equivalent such as C connected with the clamps and passing
round pulleys D' carried by the said levers and means such as described for fastening
the levers together the whole constructed and adapted to operate substantially as
described and illustrated in the accompanying drawings.
3. In a frame fastening device a clamp such as B carrying a pulley or equivalent
between the two plates for the purpose of obtaining a central pull substantially as
described and illustrated in Fig. 3 of the accompanying drawings.
4. The combination and arrangement of parts constituting the complete frame
fastening device substantially as described and illustrated in the accompanying
drawings.
F. C. STEWART.
W. P. Thompson & Boult,
Agents for the Applicant.