Living Hinge Generator

How to use this living hinge generator

1. Set units, thickness, and kerf

   Choose millimeters or inches, then pick a material preset or type your own thickness. Replace the kerf with a value measured on your own machine.

2. Set the board and the hinge zone

   Enter the board size, then place the flexible band with the alignment control or a custom start. If you already know the inside radius and the angle, apply the recommended width before you export.

3. Set the slots and read the preview

   Set cut length, the bridge, and line spacing, then pick a row layout. Use Fit to see the whole board, and Zoom kerf when you want the on-screen stroke drawn at the beam width.

4. Download SVG or DXF

   Choose Download SVG or Download DXF. Copy SVG puts that same file text on the clipboard. This page does not make G-code.

5. Cut a test strip first

   Export test strip writes a small outlined piece with the same cut length, bridge, line spacing, kerf, and row layout. If it snaps, lengthen the bridge or spread the lines. If it stays stiff, bring the lines closer or shorten the bridge, then cut another strip.

Pattern parameters explained

Cut lines run along the height of the board, parallel to the bend axis. The sheet curves across the width, and hinge width is the material that travels around the arc. Flat areas outside that band stay uncut.

Board width and height

These are the outside dimensions of the rectangle. The optional outline is that same rectangle, cut on the centerline. After import, the measured width should match the number you entered.

Hinge width and start

Hinge width is only the flexible band. Start is the distance from the left edge of the board to the left edge of that band. Left, center, right, and full width rewrite the start for you. Cut lines are centered inside the band, so the first and last lines sit slightly in from its edges.

Top and bottom margin

Margins keep slots off the top and bottom edges. Usable height is the board height minus both margins, and at least one full cut has to fit there. A few millimeters of margin stops a slot from breaking out through the edge.

Cut length

Cut length is the length of each slot along the cut line, before kerf. Longer slots leave fewer connectors, so the sheet usually bends more easily and also has less material holding it together. The pattern repeats cut, bridge, cut, bridge, and centers that repeat between the margins.

Bridge, the gap along a line

The bridge is the uncut gap between two slots on the same line. Other generators may call it a vertical gap or a link. The file draws the centerline you asked for. A real beam also burns about half the kerf past each end, so the solid left in the sheet is about the bridge minus the kerf. If that remainder is tiny, the connectors can char through.

Line spacing

Line spacing is the center-to-center distance between cut lines, across the hinge. Other tools may call this step, horizontal gap, or density. Closer lines add more places that can flex. Spacing has to stay larger than the kerf, or neighboring slots merge and the sheet can separate.

Thickness and kerf

Thickness is used for the bend-width estimate and the density hint. It does not change the drawn slot length. Kerf is your beam width. A practical check is to cut a 20 mm square, measure what is left, and divide the missing width by two. The preview can draw strokes at that kerf. The downloaded paths stay on the centerline.

Row layout and outline

Staggered rows shift every other line by half a period, so a bridge sits beside the middle of a slot. That brick layout is the usual living hinge. Aligned rows stack the bridges, which is useful on a comparison strip. Leave the outline on when this file is the whole part. Turn it off when you will paste the slots into a drawing that already has a border. The dashed hinge-zone box is never written into the file.

Calculate hinge width for a 90° bend

The band has to be long enough to wrap the curve. This page uses the arc at the middle of the sheet, the same idea as a bend allowance with the neutral line halfway through the thickness. Convert the angle to radians with degrees × π / 180. Inside arc = inside radius × radians. Recommended hinge width = (inside radius + thickness / 2) × radians. Outside arc = (inside radius + thickness) × radians.

Example: 90°, 30 mm inside radius, 3 mm sheet. Radians are π/2. Inside arc ≈ 47.12 mm. Recommended hinge width ≈ 49.48 mm. Outside arc ≈ 51.84 mm. Apply the recommendation and the form writes that width into the pattern. A centered band keeps its side flats and grows the board if the new band needs more room. A 180° bend with a 10 mm inside radius in the same sheet needs about (10 + 1.5) × π ≈ 36.13 mm of hinge.

The number is a length, not a strength test. Slots open, bridges twist, and kerf has already removed a little material, so the part can curl tighter than the mid-thickness arc. Plywood, MDF, and acrylic fail at different radii. If the band is shorter than the recommendation, the sheet has to stretch or crack to reach the angle. Prove the radius on the test strip. The density hint only compares bridges and line spacing with the thickness.

Material notes (plywood, MDF, acrylic)

Presets load a 3 mm starting pattern. They are not a material library and they are not approval to cut. Change the numbers to match the sheet in front of you, and cut the test strip from that same sheet.

Birch plywood

The default is 3 mm birch plywood: 14 mm cuts, a 2.5 mm bridge, 3.5 mm between lines, and a 0.15 mm kerf. A common workshop habit is to run the face grain across the cut lines, along the hinge width, so the outer veneer is less eager to split. Glue lines matter as much as the face. If the veneer cracks on the test strip, lengthen the bridge before you shrink the radius.

MDF

MDF has no grain to plan around. It cuts easily and breaks easily. The preset uses a slightly shorter cut and closer lines than the plywood start, still for 3 mm. Do not treat an MDF living hinge as a structural hinge. Seal the faces after the bend works, so the test is of the real board.

Acrylic

Cast acrylic can form a living hinge and can also craze or snap with little warning. The preset lengthens the cuts and the bridges and opens the line spacing compared with the plywood numbers. Extruded and cast sheet behave differently. If the test strip turns white at the bridges, stop and increase the radius or the bridge.

Power, speed, passes, and air assist live in your cutter, not in this file. If the measured kerf is wider than the bridge, the page refuses to draw the pattern, because the connectors would be gone.

Frequently asked questions

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