Adjusting Bi-Fold Door Hinges: Align Reveal Gaps with Millimetre Precision

A bi-fold door hinge connects two door leaves and can be adjusted with millimetre precision in height, depth, and lateral tilt using three integrated adjustment screws on the cross mounting plate to achieve an even gap pattern.

Bi-fold doors are frequently used on corner cabinets or wide bi-folding cupboards. The kinematics of this system require precise coordination between two hinge types: the cabinet carcase is typically fitted with a wide-angle concealed hinge (often with an opening angle of 155° or 165°), whilst the actual bi-fold hinge connects the two door panels together. If the gap reveal is uneven, the doors stick, or they rub against one another during closing, the mechanism must be readjusted.

This guide is aimed at fitters and experienced tradespeople who need to adjust cabinet doors and align gaps accurately on alternatives to well-known manufacturers such as Hettich or Blum. Adjusting a bi-fold hinge works much like aligning a gear train: every turn of a screw on one component affects the geometry of the entire system.

Technical Prerequisites and Preparation

Before adjusting the furniture hinges, ensure that the cabinet carcase is completely level and square. If the cabinet itself is warped or out of alignment, hinge adjustments cannot fully compensate for it.

Bi-fold hinges feature a standard cup drilling diameter of 35 mm. They are usually secured to the door leaf with chipboard screws or pre-mounted expanding dowels. Adjustments are carried out exclusively using the adjustment screws on the hinge arm, not by undoing the cup fixing screws.

Tools Required

Only a few tools are needed for adjustment. However, using the correct driver bit is crucial to avoid damaging the screw heads.

• PZ2 Pozidriv screwdriver: Virtually all European fitting manufacturers use the PZ profile for adjustment screws. A PH (Phillips) screwdriver will slip and ruin the drive recess.
• Folding rule or vernier calliper: For checking the gap width precisely.
• Spirit level: To verify that the carcase is plumb and level.
• Feeler gauge (optional): For ultra-precise gap measurements, particularly when internal pull-outs are housed behind the door.

Step-by-Step Guide: Adjusting Bi-Fold Door Hinges

The goal of the adjustment is a parallel reveal with a typical gap of 1.5 mm - 3.0 mm between the door leaves and between the door and the carcase. Proceed systematically in the following order.

Step 1: Analyse the Gap Pattern

Close the bi-fold door and inspect the gaps.

• Is the gap between the two door leaves wider at the top than at the bottom?
• Does the folding edge rub against the adjacent door leaf during closing?
• Does the door stand away from the carcase when fully closed?

Make a note of any deviations before picking up your screwdriver.

Step 2: Height Adjustment (Vertical Alignment)

Height adjustment ensures that the top and bottom edges of the door leaves align flush with one another. This adjustment is made on the cross mounting plate screwed to the panel.

1. Open the bi-fold door fully.
2. Loosen the two fixing screws on the mounting plates of all bi-fold hinges on the affected door by about half a turn.
3. Manually slide the door leaf up or down. The adjustment range on most fittings is ± 2 mm.
4. Hold the door in the desired position and re-tighten the screws firmly by hand.
5. Check whether the horizontal alignment of the doors is now flush.

Step 3: Lateral Adjustment (Gap Width and Tilt)

Lateral adjustment regulates the distance between the two door leaves. The corresponding adjustment screw is usually located near the front of the hinge arm (close to the cup).

1. Turn the front adjustment screw clockwise to pull the door leaf closer to the adjacent panel (narrowing the gap).
2. Turn the screw anti-clockwise to increase the distance (widening the gap).
3. To straighten a misaligned door (e.g. gap wider at the top than at the bottom), adjust the hinges differently. Turn the screw in on the top hinge and back it out slightly on the bottom hinge until the reveal runs parallel.

Step 4: Depth Adjustment (Flushness and Closing Pressure)

Depth adjustment determines the distance between the door leaf and the front edge of the carcase when closed. If the bi-fold door gapes open in the centre or binds mechanically when closing, the depth must be corrected. The screw for this is located at the rear of the hinge arm.

1. Slightly loosen the rear fixing screw. On modern hinges with cam depth adjustment, turn the eccentric cam screw directly.
2. Slide the door leaf 1 mm to 2 mm forwards or backwards.
3. Re-tighten the fixing screw.
4. Test the closing action. The bi-fold door must not be under tension when closed. The gap between the folded leaves should provide adequate clearance for the hinge kinematics.

Step 5: Coordination with the Wide-Angle Hinge

A bi-fold door system only functions smoothly when the main hinge on the carcase is correctly aligned. When adjusting the bi-fold hinge, always check the wide-angle concealed hinge as well. Often, altering the depth of the full overlay hinge on the carcase by a minimal amount is enough to stop the entire bi-fold door from catching.

Common Mistakes During Hinge Adjustment

Even experienced installers occasionally encounter issues when setting up bi-fold doors. Avoid the following mistakes:

• Using excessive force on adjustment screws: The threads in hinge arms are fine. If a screw stops turning, the maximum adjustment travel (usually ± 2 mm to ± 3 mm) has been reached. Over-tightening will strip the fitting.
• One-sided adjustments: On doors with three or more hinges, do not adjust only the top and bottom hinges. The centre hinge must be adjusted in parallel; otherwise, the hinge arm will bend and put the door under tension.
• Incorrect order of steps: Always start with height adjustment, followed by lateral adjustment. Finish with depth adjustment, as this sets the final gap clearance in the closed position.

Interaction with Internal Drawers

Drawer systems are frequently installed inside corner or larder cupboards fitted with bi-fold doors. Precise adjustment of the bi-fold door is essential here to ensure the door leaves clear the internal opening completely when opened. If the door protrudes even a few millimetres into the internal carcase clearance, the pull-outs will collide with the inside of the door.

For such cupboard configurations, internal drawer runners must be matched precisely to the hardware layout. Depending on the weight of the contents, full extension drawer runners are used to bring the entire contents clear of the carcase. If concealed installation is preferred, cabinetmakers rely on under-mount drawer runners.

The choice of runner length depends on the carcase depth. For standard wall units or narrow base cabinets, a kitchen cabinet drawer runner 30 cm or a kitchen cabinet drawer runner 40 cm is frequently used. For deep larder units with bi-fold doors, longer versions such as a kitchen cabinet drawer runner 60 cm are required.

The closing mechanism of internal drawers also matters: soft close drawer runners prevent the drawer from slamming into the closed bi-fold door if it is shut too early. If a handleless look is desired for the interior, push to open drawer runners are an ideal choice.

FAQ – Frequently Asked Questions About Door Adjustment

Why does the bi-fold door no longer snap shut on its own? This is usually caused by incorrect depth adjustment. If the door leaves are pressed too tightly together, the hinge spring mechanism binds. Increase the gap width by 1 mm using the depth adjustment screw.

Can I use a standard concealed hinge as a bi-fold hinge? No. A standard concealed hinge has different kinematics and a fixed pivot point designed for mounting onto a carcase side (such as a full overlay or inset application). A bi-fold hinge joins two moving door leaves and requires a specialised pivot geometry to clear the panel thicknesses as they fold together.

What opening angle is required for the main hinge on the carcase? For bi-fold doors, the hinge on the carcase (supporting the first door) must be a wide-angle hinge. Opening angles of 155° or 165° are standard to allow the fully folded door assembly to swing clear of the cabinet opening.

How many times can cabinet doors be adjusted before the thread wears out? When handled correctly with a PZ2 screwdriver, adjustment screws can be adjusted indefinitely. Thread stripping occurs in 90 % of cases due to using the wrong screwdriver profile (PH instead of PZ) or applying excessive torque.

Related Components for Cabinet Making

If you are planning or upgrading the interior layout of your units alongside adjusting hinges, you will find a broad selection of technical fittings at furnica.co.uk. For building bespoke pull-outs, we offer complete drawer systems.

If you store heavy items such as cookware or tools in your cabinets, fitting heavy duty drawer runners designed for high load capacity is recommended. For smaller retrofit projects in bathroom or office furniture, classic roller drawer runners provide a proven, low-maintenance solution.