SERRE-JOINT A ONGLET

MITER KEEPER

Abrégé anglais

In the joining of 2 pieces of wood using 45 degree miter joints.
this invention enables a standard spring clamp to provide equal
pressure to each side of the joint at 90 degrees to the faces
being joined. It also simultaneously traps the 2 pieces to be
joined at 90 degrees to each other, thereby eliminating the need
for further adjustment.

Revendications

8.
CLAIMS
The embodiments of the invention in which an exclusive property
or privilege is claimed are defined as follows:
1. A manually operable tool for clamping miter joints
comprising a retaining rod and an adjustable squaring block.
2. A tool as defined in Claim 1, in which the squaring block
is threaded to accept the retaining rod which can then be
shortened or lengthened to alter the distance between the
squaring block and the right angle on the retaining rod
providing a range of thicknesses of material to be held
between the jaws of the clamp.
3. A tool as defined in Claim 1, in which the squaring block
provides more than one threaded hole to accept the retaining
rod so that the inside height of the material to be clamped
has a range of bearing surface against the squaring block on
the inside of the assembled joint.
4. A tool as defined in Claim 1, which enables the jaws of
the clamp to provide equal pressure at right angles to the
miter faces to be clamped and equidistant from the inside
edge of the joint to the outside edge of the joint.
5. A tool as defined in Claim 1, where the squaring block
automatically holds the material at right angles to each
other and provides an instant visual check of the integrity
of the 90 degree angle between the 2 pieces of material.

9.
6. A tool as defined in Claim 1, which enables the
operator to view the entire length of the outside edge of
the assembled miter joint to inspect the integrity of the
miter joint.

Description

CA 02278170 1999-07-16
LIST OF DRAWINGS
In drawings which illustrate embodiments of the invention,
Figure 1. is a top view of a standard spring clamp and is
intended to show how such a common clamp without this invention
will not remain on the pieces to be joined.
Figure 2. is a top view and elevation of the device called
"MITER KEEPER" which will enable the standard clamp to
perform the function of clamping the two pieces of material
together by providing pressure on each side and at 90 degrees to
the miter faces to be joined.
Figure 3. Illustrates the "MITER KEEPER" device in use.

CA 02278170 1999-07-16
3.
SPECIFICATION
This invention relates to the direct clamping of 2 pieces of
material ( wood, metal or plastic ) using 45 degree miter joints.
It is common in devices used for clamping a miter joint, that they
do not provide clamping pressure at 90 degrees to the faces being
joined. Rather, they merely hold the 2 pieces of material while
the 2 miter faces are touching each other but not under direct
pressure. These current devices also allow slippage of the
material or distortion of the miter joint until proper alignment
of the 2 pieces of material is finally adjusted but even then,
clamping pressure is not applied where it is needed. i.e. At 90
degrees to the faces being joined.
A standard spring clamp cannot grip the material due to the fact
that its own pressure squeezes it right off the material.
(See Figure 1.)

CA 02278170 1999-07-16
This invention utilises the effect of clamp slippage and the
problem becomes a benefit.
I have found that a retaining rod with a square block placed
between the inside of the joint and the back of the clamp not
only prevents the clamp from slipping off but also provides
additional clamping pressure to the inside of the 2 pieces
being joined and at the same time, squares the material. Now
that the clamp is prevented from slipping, the clamp jaws are
able to concentrate their pressure equally on each side and at
90 degrees to the surfaces being joined.(See Figure 2.)
The Miter Keeper can be used by placing the squaring block(See
Figure 2.) on the inside of the material and the other end of
the retaining rod behind the notch formed by the handles of the
clamp or the end of the retaining rod can be inserted where the
clamp spring is retained by a pin.
The clamp pin can be removed and the retaining rod when inserted
will perform the same function as the pin. (i.e. Holding the
pieces of the clamp together).