A wood mitre joint is made by bevelling two vertical panels together at 45 degrees, to form a 90 degree corner, with no end grain showing. This makes the mitre joint visually appealing and is just one of the traditional jointing methods used by Polmac (UK) Ltd to make custom made, wood presentation boxes, promotional boxes and gift boxes.
Inserting A 'Tongue' Into Mitre Joint Groove
Mitre joints, without additional strengthening are only slightly stronger than butt joints, because the ends are cut at 45 degrees and this creates a wider surface area for adhesive to be applied. This conceals the end grain, thus giving the corner joint an uninterrupted 'clean' appearance.
The best results for mitre joints are achieved by cutting the angle of the joint with a drop saw rather than a hand saw, as this creates neat and very straight edges. However, for consistent accuracy Polmac (UK) Ltd uses a special mitring machine.
Assembling Sides Of Box
Mitre joints don't require much holding strength. However, for making wooden boxes, additional strengthening is required.
After the panels are mitred, two narrow grooves are cut at the centre and the entire length of each mitred surface. Then, a wood 'tongue' is glued and tapped into one groove, leaving a protrusion of about 3 -4 mm depending on the thickness of the panels.
Tapping The Mitre Joints Together
The second panel is then glued and tapped into position creating a much stronger 'tongue & groove' joint. This process is repeated for the two remaining wood panels, creating the sides of the wood box.
The entire assembly, comprising four mitred panels is then placed in a special metal cramp that ensures the joints are tight and the assembly perfectly square, during the glue drying process.
Cramping Sides Of Box
When the glue has dried, the excess tongues are carefully removed and the top and bottom ends of the 'box' are sanded off to present a perfectly even surface ready for the base and lid panels to be glued into position.
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