Yes, installing a piano hinge on a long cabinet door is well within reach for a capable DIYer. It's not restricted work under NZ law, so no licence is required — but it does demand careful measuring, a steady hand, and the right hardware for the job. Get it right and you'll have a door that swings smoothly and lasts for years.
What Is a Piano Hinge?
A piano hinge (also called a continuous hinge) is a long, narrow hinge that runs the full length — or most of the length — of a door or panel. Unlike standard butt hinges, it distributes load evenly along the entire edge, making it ideal for tall, heavy, or frequently used cabinet doors. You'll find them on tool cabinet lids, workshop benches, fold-down tables, and long wardrobe doors.
They're typically made from steel, stainless steel, or aluminium, and come in standard lengths (commonly 1200 mm or 1800 mm) that can be cut to size with a hacksaw or angle grinder.
Tools and Materials You'll Need
- Piano hinge (sized to suit your door — aim for about 25–50 mm shorter than the door height)
- Tape measure and pencil
- Combination square
- Drill and drill bits (including a countersink bit)
- Screwdriver or impact driver
- Hacksaw or angle grinder (if trimming the hinge)
- Clamps or a helper
- Sandpaper or a file (to smooth cut ends)
- Appropriate screws (usually supplied or matched to hinge gauge)
For timber cabinet doors, use countersunk wood screws that match the hinge leaf width. For MDF or particleboard, consider coarse-thread screws or even machine screws with barrel nuts for a stronger hold.
Choosing the Right Hinge
Piano hinges come in different gauges (thicknesses) and knuckle sizes. A heavier door needs a heavier-gauge hinge. As a rough guide:
| Door Weight | Recommended Gauge |
|---|---|
| Light (up to ~5 kg) | 1.0–1.2 mm |
| Medium (5–15 kg) | 1.5–2.0 mm |
| Heavy (15 kg+) | 2.5 mm or thicker |
Stainless steel is worth the extra cost in kitchens, laundries, or anywhere moisture is present. Check with your local supplier at Bunnings or Mitre 10 for what's available in NZ.
Step-by-Step Installation
1. Measure and Cut the Hinge
Measure your door height. Cut the hinge so it sits about 25 mm from the top and bottom of the door — this prevents the hinge from fouling on the cabinet frame and gives a neat finish. Use a hacksaw and file the cut end smooth to remove burrs.
2. Mark the Screw Holes
Lay the hinge along the door edge and use a combination square to centre it on the edge. Mark every second or third hole with a pencil — you don't need to fill every hole initially, but more screws mean more strength.
3. Pre-Drill and Countersink
Always pre-drill pilot holes to avoid splitting timber or cracking MDF. Use a countersink bit so screw heads sit flush. This step is especially important near the ends of the hinge.
4. Attach the Hinge to the Door First
Fix one leaf of the hinge to the door edge, checking it's straight with your square. Drive screws snugly — don't overtighten, especially in MDF.
5. Position the Door on the Cabinet
This is where a helper or clamps are invaluable. Hold or clamp the door in its open position against the cabinet frame, ensuring even gaps (called reveals) at top and bottom. A consistent 2–3 mm gap is standard.
6. Mark and Fix to the Cabinet Frame
With the door held in place, mark the cabinet-side holes through the hinge. Remove the door, pre-drill, then reattach and drive the screws. Check the door swings freely before driving all remaining screws.
7. Final Check and Adjustment
Open and close the door several times. It should swing smoothly with no binding or sagging. If the door drops at the latch side, check that all screws are tight and the hinge is fully seated.
Common Mistakes to Avoid
- Skipping pilot holes — splits timber and weakens the joint
- Using screws that are too long — they can break through the face of the door
- Not checking for square — a door hung out of square will bind or gap unevenly
- Ignoring the substrate — MDF and particleboard hold screws poorly; consider using PVA glue in addition to screws, or fitting a solid timber lipping first
When to Call a Professional
While piano hinge installation is DIY-friendly, there are situations where it's worth calling a qualified joiner:
- The cabinet is a built-in or structural unit that forms part of the building fabric
- The door is very heavy (over 20 kg) and requires precision fitting to avoid strain on the cabinet carcass
- You're working with high-end cabinetry where a mistake could be costly to fix
- The existing frame is damaged, out of square, or needs remedial work before a new hinge will sit correctly
A skilled joiner will have the tools and experience to get a perfect result quickly. You can find qualified local joiners on tradedirectory.co.nz.
