How to Mark and Drill for a Furniture Lock — Step-by-Step Guide

July 30, 2026

A furniture lock secures cupboards and drawers against unauthorised access; exact installation requires precise determination of the backset and cylinder diameter to drill the hole for the lock cylinder with millimetre accuracy in the furniture front.

Retrofitting or replacing a lock on furniture is a classic task in interior fittings. Whether it is a private wardrobe for 2 people in which a lockable compartment needs to be integrated, or an office pedestal – the mechanical mechanism does not tolerate measuring errors. A drill hole offset by just a few millimetres inevitably leads to the bolt jamming or the striker plate failing to engage cleanly.

This guide is aimed at fitters and experienced DIY enthusiasts. It covers the professional installation of a classic surface-mounted rim lock with cylinder. With tools prepared, the pure working time per lock is approximately 15 to 25 minutes.

The Key Technical Parameters Before Drilling

Before putting drill to wood, two crucial dimensions of the lock must be understood and checked. Without these values, accurate positioning is impossible.

Backset: This is the distance from the outer edge of the lock (which sits flush with the door edge) to the exact centre of the lock cylinder. Common backset measurements for furniture fittings are 15 mm, 20 mm, 25 mm, 30 mm, or 40 mm.
Cylinder diameter: This dimension determines the diameter of the drill bit required. A standard furniture lock cylinder often has a diameter of 19 mm, 20 mm, or 22 mm. The drill bit must match this dimension precisely. A hole that is too large leads to a loose cylinder, whilst a hole that is too small makes insertion impossible.

Required Tools and Materials

For clean edges without tear-out, especially on coated chipboard or MDF, sharp and precise tools are essential.

Drill or powerful cordless drill-driver
Forstner bit or wood bit in the exact cylinder diameter (e.g. 19 mm)
Wood drill bit for pre-drilling fixing screws (typically 2 mm or 2.5 mm)
Vernier calliper or a precise tape measure
Bradawl (alternatively a sharp nail)
Pencil and masking tape
Backing board (a piece of scrap wood) and a G-clamp
Suitable wood screws (usually 3.0 x 15 mm or 3.5 x 15 mm, countersunk)

Step-by-Step Guide: Installing a Furniture Lock

The following guide describes installation on a standard lay-on door (the door fully overlays the cabinet carcase edges). For inset doors or drawers, the drilling principle remains identical; only the position of the striker plate changes.

Step 1: Determine Position and Apply Tape

Determine the desired height of the lock. On a sideboard for TV, the lock is usually positioned in the upper third of the door; on drawers, exactly in the centre of the front. Mask the area where the hole will be drilled thoroughly on both the front and back of the door using masking tape. The tape prevents the melamine coating or veneer from getting marked during marking out and splintering during drilling.

Step 2: Mark Backset and Height

Work on the inside of the furniture door. Mark the exact height as a horizontal line. Now measure the backset inwards from the door edge (the side that opens). Mark this point on the horizontal line. Ideally, use a vernier calliper for this measurement, as a deviation of even 1 mm will cause tension in the locking mechanism.

Step 3: Centre the Drill Hole

Place the bradawl exactly on the marked crosshair and press a clear indentation into the wood. This centring is essential. Without this guide point, the centre point of the Forstner bit would wander on the smooth surface.

Step 4: Drill the Cylinder Hole

Clamp the scrap wood firmly as a backing board to the outside of the door using the G-clamp, positioned directly over the planned drilling location. A blunt bit without backing support tears the wood fibres on the exit side like a plough turning soil.

Place the Forstner bit on the inside at the marked indentation. Drill at high speed but with low pressure, precisely at a 90° angle through the door until the bit enters the backing board. Remove the masking tape and vacuum away any wood chips.

Step 5: Align and Screw the Lock Case

Insert the lock from the inside through the drilled hole. The cylinder must sit flush on the outside of the front. Align the lock case precisely parallel to the door edge. Mark the fixing holes of the case using the bradawl.

Remove the lock again and pre-drill the markings with a 2 mm wood drill bit. Watch the drilling depth – do not drill all the way through the front. Reinsert the lock and screw it down securely using the appropriate wood screws (PZ or TX drive). Do not over-tighten the screws, as the thread in the chipboard will otherwise strip.

Step 6: Position the Striker Plate

When locked, the bolt of the lock must engage with the carcase. A striker plate or striking bracket is installed for this purpose. Turn the key so that the bolt is extended. Close the door as far as possible and transfer the top and bottom edges of the bolt onto the inside of the carcase using a pencil. Measure the distance of the bolt to the inside face of the door front and transfer this measurement to the carcase as well.

Position the striker plate against these markings, pre-punch the screw holes, and fix it in place. Test the locking operation. The key must turn without noticeable resistance.

Specific Application Areas in Cabinet Making

The method of installation varies slightly depending on the piece of furniture and its function:

Office furniture and desks: For mobile pedestals fitted beneath a cable grommet for desk, central locking systems are often used. Here, the cylinder engages with an aluminium bar that locks multiple drawers simultaneously. Drilling the top front is carried out in the same way as described in the guide above.
TV furniture: On a lowboard for TV, locks are frequently used to protect expensive media equipment from children. Compact surface-mounted rim locks with a short backset (e.g. 15 mm) are ideal here, as the frame widths are often narrow.
Wall cabinets: If flap doors equipped with a gas strut for heavy flaps are being secured, the striker plate must be anchored particularly solidly into the top panel, as the gas strut exerts continuous pressure on the bolt when closed.
Kitchen furniture: In cupboards, such as those next to a dish drying rack for wall unit where cleaning agents are safely stored, attention must be paid to corrosion-resistant materials (e.g. nickel-plated steel), as higher humidity levels can occur here.

Common Mistakes During Lock Installation

Incorrect backset measured: If the dimension is measured from the overlaying door edge rather than the inner reference edge, the lock will sit too far out. The bolt will then fail to close because the lock case hits the carcase.
Tear-out around drill holes: This usually happens when omitting a backing board or using a blunt HSS twist bit instead of a dedicated wood or Forstner bit.
Bolt jamming: This occurs if the striker plate is not aligned precisely. If the clearance is too tight, the bolt rubs against the metal. To fix this, loosen the screws on the striker plate slightly, shift the plate by 1 to 2 mm, and retighten.

FAQ – Frequently Asked Questions About Lock Installation

How do I measure the backset correctly on an old lock? Measure on the back of the removed lock. Place the tape measure against the edge from which the bolt extends. Measure from this edge exactly to the centre of the round cylinder housing. This value in millimetres is the backset.

Is there a cabinet lock that does not require drilling? Yes, alternatives exist for temporary solutions or child safety. Magnetic invisible locks are stuck to the inside of the front and the carcase with adhesive or fixed with extremely short screws. They are unlocked from the outside using a strong magnet. Adhesive locks fitted externally across corners also require no drilling. However, they provide no real break-in protection, serving purely as an access deterrent.

How do I pre-drill if the striker plate is to be fixed with an M6 threaded insert? On heavy doors or under high loads, striker plates are sometimes secured with machine screws into threaded inserts. To pre-drill for an M6 threaded insert in wood or MDF, you generally need a wood drill bit with a diameter of 8 mm to 8.5 mm (depending on the external thread of the insert; check manufacturer specifications). Drill precisely perpendicular, countersink the hole minimally, and screw the insert in flush using an Allen key.

Which drill bit is best suited for the cylinder hole? A Forstner bit or a machine bit is strictly necessary. Standard twist drill bits in sizes of 19 mm or 20 mm cause severe tear-out in wood and wander easily. A Forstner bit cleanly scores the perimeter first before the internal blades remove the waste material.