What Is Bridging in Laser Cutting? (Floating Islands Explained)
By Amir Baker, founder of StencilCut · Updated
Bridging in laser cutting means adding small connectors that join otherwise-floating pieces of a design to its main body, so the whole thing cuts as one connected piece. A "floating island" is any region, the centre of an O, the dot of an i, a highlight inside a shape, that is completely surrounded by a cut line and would simply drop out when the laser finishes. Bridges hold those pieces in place.
Why floating islands happen
A laser cuts along the outline of each shape. If a shape is fully enclosed inside another (the hole in a donut, the inner loop of a letter), the laser cuts all the way around it and it falls free. On a stencil this is fatal: the letter centres drop out and you are left with solid blobs. Any design with enclosed negative space has this problem.
How bridges fix it
A bridge is a thin uncut connector left between a floating island and the surrounding material, so the island stays attached. On a stencil "O", small bridges hold the centre in place; on a script sign, connectors keep the loops attached. Good bridges are placed along natural lines and are just wide enough to hold (around 1-2mm), so they are barely noticeable but strong enough to survive handling.
Manual vs automatic bridging
You can add bridges by hand in design software, slow and easy to miss an island. Or a tool can detect every disconnected island automatically (via a connected-components scan) and place bridges to the nearest body, then re-export a one-piece file. Automatic bridging is far faster and does not miss the small islands that ruin a cut.
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Auto-bridge an SVGFrequently asked questions
What does bridging mean in laser cutting?
Bridging is adding small uncut connectors that join floating pieces of a design to the main body so the whole piece cuts as one and nothing falls out.
Why do the centres of my letters fall out?
They are floating islands, fully enclosed by a cut line. Add bridges connecting each centre to the surrounding material so they stay attached.
How wide should a bridge be?
Around 1-2mm is typical: wide enough to hold the piece during cutting and handling, narrow enough to be unobtrusive. Thicker material can use slightly wider bridges.
Can bridging be automatic?
Yes. Tools can scan a design for every disconnected island and place bridges automatically, then export a one-piece SVG/DXF, much faster and more reliable than doing it by hand.
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