Hole distance to the bend line

The rule of thumb

If a hole sits too close to a bend line, the bending motion drags it out of shape. A common rule of thumb in sheet metal practice:

minimum distance (hole edge to bend line) = inside bend radius + 2.5 × material thickness

This is a rule of thumb, not a hard ISO standard — the actual achievable distance also depends on the material and tooling. For critical tolerances: have it checked, or consider adding the hole after bending instead of before.

Why this is often missed

On a 2D drawing, a hole close to a bend line doesn't look like a problem — only once the part is actually bent does the hole turn out elliptical. This is one of the most common reasons a part needs rework after laser cutting. Check holes near a bend line already at the design stage.

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