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Mitre joint
A mitre (miter) joint is made by cutting each of two parts across the main surface, usually to form a 90 degree corner.
Mitre joint, schematic. Shapes are drawn for illustration.
What the sources say
| Point | Detail | Source |
|---|---|---|
| Cut angle | Two pieces each cut to 45 degrees meet in a 90 degree corner | Bob Vila, University of Melbourne |
| General rule | For a corner that is not 90 degrees the cut is the meeting angle divided by two | Wikipedia |
| Use | Typical applications include picture frames, pipes and moulding | Wikipedia |
| Strength | The joint is weak; end-grain gluing is poor, and a spline or dowels can strengthen it | Wikipedia, Bob Vila, University of Melbourne |
| Accuracy | Set the saw at precisely 45 degrees and check it with a triangle | Bob Vila |
For wall art
Frame corners are mitred so the moulding profile runs round the frame without an end showing; the joint is only as strong as its glue and reinforcement.
Where the sources stop
All three sources agree on the 45 plus 45 geometry and on the weakness of the joint without reinforcement; they differ only in which reinforcement they name.
Sources
- Wikipedia: Miter joint (fetched 2026-11-12)
- Bob Vila: how to make a mitered corner (fetched 2026-11-12)
- University of Melbourne machine workshop: mitre joint (fetched 2026-11-12)
Figures from these pages are paraphrased; each page was fetched and read on 2026-11-12. Where two sources differ, both are shown.