How to Adjust Gas Struts — Step-by-Step Guide

A gas strut cannot have its spring force adjusted mechanically; adjusting a furniture flap is always achieved through the precise positioning of the mounting points and the fine alignment of the supporting hinges.

Furniture flaps in kitchen wall units or living room furniture require precise coordination of the hardware. If a flap does not stay open at the desired angle, hangs crooked, or jams when closing, this is rarely due to a defect, but rather faulty installation or misaligned geometry. This guide is aimed at fitters and experienced tradespeople who want to install flap fittings professionally and align panel gaps accurately.

The mechanics of a furniture flap work like a seesaw: altering the lever arm by moving the mounting plates even a few millimetres changes the required force and the opening angle drastically.

Preparation and Technical Fundamentals

Before picking up any tools, the technical baseline must be correct. A gas damper (correctly termed a gas strut) consists of a cylinder and a piston rod. Inside the cylinder is compressed nitrogen gas. The extension force is measured in Newtons (N). Common values for furniture flaps range between 50 N and 150 N.

It is a widespread misconception that the pressure inside the cylinder can be subsequently increased or decreased using an adjusting screw. If the force is incorrect, you must either reposition the mounting points or fit a strut with a different N rating. For large fronts made of MDF or solid wood, gas struts for heavy flaps are often required.

Tools Required

• Cross-head screwdriver (PZ2 or PH2, depending on the screw head)
• Tape measure or folding rule
• Protractor (optional, for checking the exact opening angle)
• Pencil and bradawl
• Cordless screwdriver with matching bit (for initial installation only, not for fine adjustment)

Step 1: Adjusting Cabinet Doors (The Baseline)

Every upward-opening flap is attached to the top of the cabinet carcase using hinges. Before focusing on the gas strut, you must adjust the hinges. If the flap sits crooked on the carcase, one-sided load is placed on the strut mechanism, leading to premature wear.

Most flaps are fitted using a concealed hinge (cup diameter usually 35 mm). Here is how to align the panel gaps with millimetre precision:

1. Height adjustment: Slightly loosen the two fixing screws on the cruciform mounting plate (the plate screwed to the carcase). Move the flap up or down until the horizontal gap runs parallel to the neighbouring cabinet. Tighten the screws hand-tight again.
2. Side-to-side adjustment: The adjustment screw for lateral alignment is located in the centre of the hinge arm. Turning this screw (usually within a range of +/- 2 mm) moves the flap to the left or right. When adjusting multiple cabinet hinges, turn all hinges evenly to avoid tension across the front panel.
3. Depth adjustment: The rear screw on the hinge arm secures the hinge to the mounting plate. Loosen this slightly to regulate the gap between the flap and the front edge of the carcase. A gap of 1.5 mm to 2 mm is ideal so the front does not rub against the carcase during opening.

Only once the cabinet door adjustment is complete and the gap dimensions are accurate all round should you proceed to adjusting the gas struts.

Step 2: Adjusting the Opening Angle of the Gas Strut

The opening angle of a flap (typically 75°, 90°, or 110°) is determined by the position of the mounting brackets. Standard gas struts are supplied with two brackets: one for the carcase (side panel) and one for the front (flap).

If you want to alter the angle or optimise the holding force, the screw-fixing points must be changed:

1. Front bracket attachment: The position of the bracket on the flap largely dictates the leverage. Moving the bracket closer to the hinge (upwards) allows the flap to open further, but the spring force is weaker. Moving the bracket downwards holds the flap open more firmly, but reduces the maximum opening angle.
2. Carcase bracket attachment: The same principle applies here: moving the bracket further back (into the depth of the carcase) reduces the opening angle. Moving it further forward increases the opening angle.
3. Checking symmetry: If you are using two struts on a wide flap, the measurements must match to the millimetre. Measure from the front edge of the carcase to the centre of the ball stud. A discrepancy of just 2 mm will cause the flap to twist when closing.

Workshop tip: If you need to drill new holes, use System 32. Many carcase brackets are designed to align precisely with pre-drilled 5 mm hole lines spaced 32 mm apart.

Step 3: Adjusting and Testing Kitchen Cabinet Dampers

In furniture making, the term damper is often used ambiguously. A gas strut holds the flap open, whereas a furniture damper (soft-close mechanism) ensures that the flap closes gently.

If the flap slams shut, this is not caused by the gas strut. In this case, you need to adjust the soft-close mechanism on the concealed hinge. Modern hinges feature a small lever or switch in the hinge cup that enables or disables the damping. On lightweight doors, activating the damper on only one of the two hinges is often sufficient, as the flap might otherwise close too slowly.

Conversely, if the flap does not stay open on its own, the spring force (in Newtons) is too low. Check the markings on the cylinder. If it reads 60 N but the front is heavy MDF with a mirror, you will need to replace the struts with a stronger version (e.g. 100 N or 120 N).

Common Installation and Adjustment Errors

Tradespeople and fitters often encounter the same issues when working with flap fittings. Avoid the following common pitfalls:

• Confusing the application type: Check whether your hinges are designed for a full overlay (front sits fully over the carcase side) or an inset application (front sits flush between the carcase sides). For inset doors, the position of the gas strut bracket shifts backwards by the material thickness of the front (usually 16 mm or 19 mm).
• Incorrect cylinder orientation: The thick side (the cylinder body) should point upwards when closed, with the thin piston rod pointing downwards. This ensures that the internal oil lubricates the seals and that end-position damping functions correctly when opening.
• Over-specifying the force: More is not always better. If 150 N struts are fitted to a lightweight chipboard flap, significant force is needed to close it, which can tear the hinges out of the carcase.
• Using the wrong tools: Never use a cordless screwdriver on hinge adjustment screws. The threads inside the cruciform mounting plate or hinge arm strip easily. Always use a manual screwdriver.

Aesthetics and Carcase Integration

Alongside pure functionality, design plays a key role in quality furniture. Hardware fittings should match the carcase interior in colour. For dark wood finishes or anthracite carcase interiors, gas struts black are ideal. In classic white kitchen wall units, which often house a dish drainer for wall cabinets, gas struts silver or gas struts white blend more harmoniously into the overall look.

FAQ — Frequently Asked Questions About Adjustment

Can you reduce the pressure in a gas strut? No. The nitrogen charge inside the sealed cylinder is set to a specific pressure. Mechanically reducing the force is not possible with standard furniture fittings. If the flap is too stiff to close, a model with a lower Newton rating (e.g. 50 N instead of 80 N) must be installed.

Why is my furniture flap not closing completely? This usually has two causes: either the flap stays are positioned incorrectly geometrically (the piston rod bottoms out before the door reaches the carcase), or the concealed hinges are misaligned. Check the depth adjustment of the hinges and ensure the gap between the front and carcase is not too narrow.

How do I determine the correct Newton rating for my flap? The weight of the flap (including the handle) and the height of the front panel are decisive. A general rule of thumb for standard chipboard (16 mm): for front panels up to 300 mm in height and 600 mm in width, 50 N to 60 N is usually sufficient. From 400 mm in height or with heavier materials like MDF, 80 N to 100 N is required.

The flap creaks when opening — what should I do? The piston rod of the strut must not be oiled or greased, as this damages the internal seals. Creaking noises almost always originate from the ball joints at the ends of the strut or from the hinges. A tiny drop of silicone spray on the ball studs of the mounting brackets usually resolves the issue immediately.

Related Products and Categories

To further optimise the functionality of your furniture, our range provides the ideal components for any project. Whether assembling a completely new front panel or replacing existing hardware:

• Gas Struts – An overview of all standard models for light to medium-weight fronts.
• Gas Struts for Heavy Flaps – High-performance struts for solid wood and large flaps.
• Flap Fittings – Complete sets including brackets and fixing hardware.
• Flap Stays – Mechanical alternatives and lift-up stays for specialised installation requirements.

By positioning the mounting points accurately and carefully fine-tuning the hinges, you ensure that your furniture flaps open smoothly and close precisely for years to come. Take your time when aligning the panel gaps — it is the hallmark of professional installation.