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SESK: Stuff Everyone Should Know · sesk.info/weld-joint-corner

Two pieces joined at 90 degrees to form an L make which joint?

A corner joint.

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  1. Lap joint
  2. Corner joint ✔
  3. Edge joint

Why: Pieces joined at 90 degrees in an L shape make a corner joint. In a closed corner the edges sit flush; an open corner leaves a gap showing each edge.

Huh, didn't know that: Miller says corner joints are often used for square frames, such as a weld table.

The dad joke
How do you keep warm in a cold room? You go to the corner. It's always 90 degrees!
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References

Answer: Corner joint. Pieces joined at 90 degrees in an L shape make a corner joint. In a closed corner the edges sit flush; an open corner leaves a gap showing each edge.

  1. A Guide to the 5 Basic Types of Weld Joints (Miller) www.millerwelds.com/resources/article-library/a-guide-to-the-5-basic-types-of-weld-joints-and-tips-for-improving-results
    When pieces are joined at 90 degrees and take the shape of an L, they form a corner joint.
    Checked 2026-10-10.

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