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How do I fix gaps in mitered corners?

With the box secured in a vise or clamped to your bench, run the shaft of a screwdriver against the point of the corner, rolling over the fibers to conceal the gap.


The mitered corners of a box I made opened up slightly at the points when I glued it up. Is there a fix or is it too late?
—Peter Burrus, Galesburg, Ill.


Don’t panic, Peter, we’ve got a fix for you. You can close minor gaps by rolling the corners with a screwdriver, as shown above. This technique bends the delicate fibers at the corners to cover the gap. Finish up with a light sanding to remove any unevenness.

To prevent this on future projects, follow the tip below to create angles that meet perfectly. Then use a right-angle brace to guide the glue-up, eliminating any sloppiness introduced by uneven clamp pressure.

To set a precise 45° angle, raise the blade and register a drafting triangle against the body (not the teeth). After dialing in the angle, lower the blade to the desired cutting height.

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