GB2114698A

GB2114698A - Mitred corner joints between timber frame members

Info

Publication number: GB2114698A
Application number: GB08204192A
Authority: GB
Inventors: Robert Jamieson Bowes
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-02-12
Filing date: 1982-02-12
Publication date: 1983-08-24

Abstract

A mitred corner joint is formed between two timber window; sash frame members (1, 2) the ends of which are adhered together (at 7). The joint is reinforced by at least two triangular pieces (10, 11) of e.g. sheet aluminium coated with adhesive and driven into saw cuts (8, 9) so as to leave unfilled margins of the saw cuts (8, 9) which are filled thereafter by a filler. Pins (12) may be driven through the timber and the pieces (10, 11). <IMAGE>

Description

SPECIFICATION Improvements in mitred corner joints between timber frame members, particularly of window sash frames This invention relates to improvements in mitred corner joints between timber frame members, particularly of window sash frames.

The usual corner joints in timber window sash frames are mortise and tenon joints since these joints are stronger than simple mitre joints.

However, mortise and tenon joints are more timeconsuming and therefore more costly to produce than mitre joints. Recent efforts to strengthen mitre joints have involved the use of moulded plastics inserts and the formation of recesses in the frame ends to be joined together for receiving the inserts. The cost of the moulded plastics inserts and the forming of the recesses add considerably to the cost of the sash frame. Also, the ends of the inserts can be seen particularly on the inner sides of the corners and thus detract from the appearance of the sash frame.

An object of the invention is to obviate or mitigate the above disadvantages.

According to one aspect of the invention there is provided a method of forming a reinforced mitred corner joint between timber frame members, particularly of a window sash frame, wherein the ends of the frame members are cut so as to form a mitred joint, the cut ends are adhered together into a mitred corner joint, at least two saw cuts are made in the joined ends from the outer side of the mitred corner joint towards but short of the inner side of the mitred corner joint so that each saw cut is in the form of a right-angled triangle with the hypotenuse thereof forming the end of the saw cut, a correspondingly triangular piece of sheet metal of slightly smaller dimension and coated with adhesive is driven into each saw cut sufficiently to leave margins of the saw cut unfilled on the outer side of the mitred corner joint, and applying a filler to the otherwise unfilled margins of the saw cuts.

According to another aspect of the invention there is provided a timber window sash frame wherein each corner is formed by the above method.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing of a corner of a timber window sash frame, with parts of the frame member ends cut-away.

In the drawing, the ends of two typical window sash frame members 1 and 2 are shown. Each member has an outer surface 3 provided with a longitudinal drainage groove 4. The inner surface 5 of each member is stepped at 6 to receive a glass pane (not shown). The ends of the members 1 and 2 are cut to form a mitred corner joint and the cut ends are adhered together at 7. Two saw cuts 8 and 9 are made in the joined ends from the outer side of the mitred corner joint towards but short of the inner side thereof. Thus, each saw cut is in the form of a right-angled triangle with the hypotenuse thereof forming the end of the saw cut. The saw cut 8 extends inwards from one side of the grooves 4 towards but short of the steps 6 and is therefore less deep than the saw cut 9 which extends inwards from the surfaces 3 towards but short of the surfaces 5.Driven into each saw cut is a correspondingly triangular piece of sheet aluminium coated with adhesive. One piece 10 is driven into the saw cut 8 and is slightly smaller than the saw cut so as to leave margins of the saw cut unfilled in the grooves 4. Likewise, the other piece 11 is driven into the saw cut 9 and is slightly smaller than the saw cut so as to leave margins of the saw cut unfilled in the surfaces 3. A filler is then applied to the otherwise unfilled margins of the saw cuts. For extra strength rustproof pins 12 may be driven through the timber and the pieces 8 and 9. If required, the timber and the pieces 8 and 9 may be drilled before the pins are applied.

By means of the invention a strong and neat joint is produced with the added advantages of low cost and weather barriers being provided at the joints by the pieces 8 and 9.

1. A method of forming a reinforced mitred corner joint between timber frame members, particularly of a window sash frame, wherein the ends of the frame members are cut so as to form a mitred joint, the cut ends are adhered together into a mitred corner joint, at least two saw cuts are made in the joined ends from the outer side of the mitred corner joint towards but short of the inner side of the mitred corner joint so that each saw cut is in the form of a right-angled triangle with the hypotenuse thereof forming the end of the saw cut, a correspondingly triangular piece of sheet metal of slightly smaller dimension and coated with adhesive is driven into each saw cut sufficiently to leave margins of the saw cut unfilled on the outer side of the mitred corner joint, and applying a filler to the otherwise unfilled margins of the saw cut.

2. A method according to claim 1, wherein pins are driven through the timber and the pieces of sheet metal.

3. A method of forming a reinforced mitred corner joint between timber frame members, substantially as hereinbefore described with reference to the accompanying drawing.

4. A timber window sash frame wherein each corner is formed by a method according to any preceding claim.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in mitred corner joints between timber frame members, particularly of window sash frames This invention relates to improvements in mitred corner joints between timber frame members, particularly of window sash frames. The usual corner joints in timber window sash frames are mortise and tenon joints since these joints are stronger than simple mitre joints. However, mortise and tenon joints are more timeconsuming and therefore more costly to produce than mitre joints. Recent efforts to strengthen mitre joints have involved the use of moulded plastics inserts and the formation of recesses in the frame ends to be joined together for receiving the inserts. The cost of the moulded plastics inserts and the forming of the recesses add considerably to the cost of the sash frame. Also, the ends of the inserts can be seen particularly on the inner sides of the corners and thus detract from the appearance of the sash frame. An object of the invention is to obviate or mitigate the above disadvantages. According to one aspect of the invention there is provided a method of forming a reinforced mitred corner joint between timber frame members, particularly of a window sash frame, wherein the ends of the frame members are cut so as to form a mitred joint, the cut ends are adhered together into a mitred corner joint, at least two saw cuts are made in the joined ends from the outer side of the mitred corner joint towards but short of the inner side of the mitred corner joint so that each saw cut is in the form of a right-angled triangle with the hypotenuse thereof forming the end of the saw cut, a correspondingly triangular piece of sheet metal of slightly smaller dimension and coated with adhesive is driven into each saw cut sufficiently to leave margins of the saw cut unfilled on the outer side of the mitred corner joint, and applying a filler to the otherwise unfilled margins of the saw cuts. According to another aspect of the invention there is provided a timber window sash frame wherein each corner is formed by the above method. An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing of a corner of a timber window sash frame, with parts of the frame member ends cut-away. In the drawing, the ends of two typical window sash frame members 1 and 2 are shown. Each member has an outer surface 3 provided with a longitudinal drainage groove 4. The inner surface 5 of each member is stepped at 6 to receive a glass pane (not shown). The ends of the members 1 and 2 are cut to form a mitred corner joint and the cut ends are adhered together at 7. Two saw cuts 8 and 9 are made in the joined ends from the outer side of the mitred corner joint towards but short of the inner side thereof. Thus, each saw cut is in the form of a right-angled triangle with the hypotenuse thereof forming the end of the saw cut. The saw cut 8 extends inwards from one side of the grooves 4 towards but short of the steps 6 and is therefore less deep than the saw cut 9 which extends inwards from the surfaces 3 towards but short of the surfaces 5.Driven into each saw cut is a correspondingly triangular piece of sheet aluminium coated with adhesive. One piece 10 is driven into the saw cut 8 and is slightly smaller than the saw cut so as to leave margins of the saw cut unfilled in the grooves 4. Likewise, the other piece 11 is driven into the saw cut 9 and is slightly smaller than the saw cut so as to leave margins of the saw cut unfilled in the surfaces 3. A filler is then applied to the otherwise unfilled margins of the saw cuts. For extra strength rustproof pins 12 may be driven through the timber and the pieces 8 and 9. If required, the timber and the pieces 8 and 9 may be drilled before the pins are applied. By means of the invention a strong and neat joint is produced with the added advantages of low cost and weather barriers being provided at the joints by the pieces 8 and 9. CLAIMS