Concealed Hinges for IKEA Billy Oxberg: Fitting Hinges & Soft-Close Retrofits

A matching concealed hinge for an IKEA Billy Oxberg door typically requires a 35 mm cup diameter and the correct overlay type to sit flush with the carcase.

Whether you want to fit an Oxberg door to an existing shelving unit, replace broken hardware, or retrofit soft-close dampers, you need to know the precise technical parameters of the hinges. An item that merely looks similar is not enough; mechanical dimensions, drilling hole diameters, and mounting plate positions determine proper function. This guide explains the technical specifications relevant for replacing or upgrading door hinges on this system.

Key Buying Criteria for Replacement Hinges

When replacing fittings on flat-pack furniture systems, standardised dimensions apply. Compatibility is determined by three main factors: the cup hole diameter in the door, the door position relative to the carcase, and the hole pattern on the side panel.

Cup Diameter and Drilling Depth

The concealed hinge is the standard joint for modern cabinet doors. The Oxberg door features a pre-drilled recess known as the cup hole. For this system, a cup diameter of 35 mm is the industry standard. Smaller 26 mm variants are not used here. The drilling depth in the door is typically 11.5 mm - 12 mm. The replacement hinge must fit precisely into this hole so that it sits flush and does not tilt when screwed in place. Compatible models can be found in the category for Concealed Hinges 35 mm.

Overlay Types: Full Overlay vs. Half Overlay

The position of the door when closed defines the required crank of the hinge arm. This is where the most common purchasing mistakes happen.

• Full Overlay: When closed, the door covers almost the entire front edge of the carcase side panel. This applies when the shelving unit stands alone or for the outer doors of a cabinet run. Straight, uncranked hinges are required for this. Corresponding hardware is listed under Full Overlay Hinges.
• Half Overlay: When two shelving units stand directly next to each other and two doors share a single carcase divider, each door may only cover half the edge (around 7.5 mm to 8 mm overlay per door on a 16 mm thick chipboard panel). The hinge arm is cranked for this setup. This variant is referred to as Half Overlay Hinges.
• Inset: The door does not sit on top of the carcase edge, but closes flush inside the side panels. For standard installations of the Oxberg series, this type is usually not used, but it is relevant for custom conversions.

System 32 Hole Spacing

The hinge is secured to the carcase using a cruciform mounting plate. Industrially manufactured furniture uses System 32. This means the pre-drilled holes in the side panel have a spacing of exactly 32 mm from one another and are positioned standardly 37 mm from the front edge. The mounting plate of the new hinge must support these distances to allow installation without drilling new holes.

Overview of Types and Options

Once the basic measurements (35 mm cup, correct overlay) are established, several technical options are available to enhance the operating comfort of your cabinet door.

Standard Hinges with 110° Opening Angle

For a direct 1:1 replacement of defective hinges, classic Concealed Hinges / Cabinet Hinges are sufficient. The standard opening angle for these doors is 110°. This allows the door to open wide enough without bumping into adjacent furniture. Corresponding models are categorised as Concealed Hinges / Cabinet Hinges 110 Degree.

Retrofitting Soft-Close Dampers

A frequent reason for replacing fittings is the desire for quieter closing. A hydraulic cylinder inside the hinge arm cushions the door over the final few centimetres and pulls it gently shut.

A strict technical distinction is important here: Soft-close pulls the door shut and cushions it. Push-to-open pushes the door open when pressed. Both mechanisms work against each other and cannot be combined in the same hinge. For cushioned closing, Concealed Hinges / Cabinet Hinges with Soft Close are the correct choice.

As an alternative to replacing the complete hinge, separate door dampers can be installed. These are either clipped onto the existing hinge (if compatible with the manufacturer) or screwed/drilled into the carcase wall as an independent component. Suitable components can be found under Door Dampers.

Which Hinge for Which Situation?

Selecting the exact fitting depends on the specific installation scenario:

• If an outer door is fitted at the edge of the shelving unit and needs to finish flush with the outside edge, then choose a full overlay concealed hinge with a 35 mm cup.
• If two units are joined together and the doors share a central partition, then a half overlay hinge is essential to prevent the doors from colliding when opened.
• If the door slams loudly shut, but you do not want to remove the existing hinges, then install a separate surface-mounted door damper on the inside of the carcase.
• If you are undertaking a complete new build or comprehensive upgrade, then invest directly in hinges with integrated soft-close and clip-on mechanisms, as these significantly speed up fitting and removing doors.

Installation Advice and Adjustment

Fitting concealed hinges requires precision, but is straightforward to carry out using standard tools.

Required tools:

• Cordless screwdriver or suitable cross-head screwdriver (PZ2)
• Tape measure or callipers
• If necessary, a wood drill bit (5 mm) for the mounting plates

Installation steps:

1. Insert the cup: Place the hinge into the 35 mm recess of the door. It must be aligned at an exact 90-degree angle to the door edge.
2. Screw in place: Secure the cup using chipboard screws (usually 3.5 mm x 16 mm) through the side screw holes into the door.
3. Attach mounting plate: Secure the cruciform mounting plate to the carcase side panel. For pre-drilled 5 mm holes (System 32), special Euro screws are used.
4. Hang the door: With modern clip-on hinges, simply press the hinge arm onto the mounting plate until it audibly clicks into place.

Aligning the door gaps (3D Adjustment): Adjusting a hinge works like tuning a guitar – tiny turns on the adjustment screws instantly alter the mechanical alignment.

• Depth adjustment: Loosening the rear screw on the hinge arm allows the door to move a few millimetres further from or closer to the carcase.
• Height adjustment: Loosening the screws on the cruciform mounting plate allows the door to be adjusted up or down by approximately 2 mm.
• Side adjustment (Overlay): The front adjustment screw in the hinge arm regulates the gap between doors. Turning it clockwise moves the door edge towards the centre of the carcase.

Frequently Asked Questions (FAQ)

What cup diameter is required for Oxberg doors? The standard hole in these doors has a diameter of 35 mm. Hinges with a 26 mm cup are too small and cannot be secured.

Can I retrofit soft-close to existing doors? Yes, this is easily done. You can either replace the complete hinges with models featuring an integrated damper cylinder, or screw a separate door damper to the inside of the cabinet carcase.

What does half overlay mean on shelving doors? A half overlay hinge is used when a vertical carcase partition is shared by two doors (left and right) simultaneously. The hinge arm is cranked so that each door covers only half the timber edge, leaving room for the neighbouring door.

Which screws do I need for the mounting plate? If the shelving unit already features a System 32 line of 5 mm pre-drilled holes, you need Euro screws. If no holes are present or you are pre-drilling yourself, use classic countersunk chipboard screws, typically 3.5 mm x 16 mm.

Why does the door not close fully after replacing the hinges? This is often caused by an incorrect depth adjustment. If the door is pulled too tight against the carcase, it binds on the hinge side. Loosen the rear adjustment screw on the hinge arm slightly and move the door forward by 1 mm to 2 mm.