Step by step
Make a living hinge that bends without snapping
A flat panel that bends round a curve and stays in one piece.
Before you start
Anybody making a curved lid, a wrap-around, or a case with a rounded corner.
- Ply or MDF, 3 mm is the usual place to start.
- A piece of scrap to test on, because the first one usually snaps.
Know what you are asking the material to do
A living hinge is a field of thin cuts that leaves narrow strips of material between them. The strips twist, and enough small twists add up to a bend.
The material is not becoming flexible. It is being weakened in a controlled pattern, and there is a limit past which it is simply broken.
Give it the radius you actually need
The tighter the bend, the more cuts and the thinner the strips. Tell it the radius you want to bend to, not a guess at a spacing.
A gentle curve on 3 mm ply is comfortable. A 20 mm radius on the same material is asking a lot, and you should expect to test it.
Cut it on scrap and bend it before you commit
Cut a strip about 60 mm wide on the same sheet you will use for the real part, and bend it round something the size of your radius.
It should take a firm push and spring back a little. If it cracks, widen the radius or use thinner material. If it feels floppy, you can tighten the pattern and save cutting time.
Every setting, and what it does
9In the order you meet them. The second line on each is what goes wrong when it is set badly, which is usually the more useful half.
Slits bend one way. The lattice bends tighter, and any way.
One of: Straight, Diamond
Panel width (mm), used when nothing is selected
Starts at 120
Panel height (mm), used when nothing is selected
Starts at 60
How long each cut in the fold is (mm).
Starts at 20
Uncut material left between slits (mm)
Starts at 1
Row spacing (mm), or diamond size on the diamond pattern
Starts at 4
Which way the panel bends.
One of: Across the width, Along the height
Panel left edge (mm), used when nothing is selected
Starts at 10
Panel top edge (mm), used when nothing is selected
Starts at 10
How to know it worked
- A test strip bends to the radius and springs back rather than staying bent.
- No strip has broken along its length.
When it goes wrong
3It snapped on the first bend.
Too tight for this material. Widen the radius, or move to a thinner or more flexible sheet. Plywood with a knot in the hinge will always break there.
It bends but feels weak.
That is a hinge doing its job. If it needs to carry load, the hinge is the wrong answer and a real joint is the right one.
It cuts very slowly.
A hinge is hundreds of small cuts. Reduce the density if the bend allows it, and check the cut order is not crossing the panel between every slit.