Window Handles with Locks: Measuring Spindle Length and Centres

Window handles with locks are a common upgrade for improving both security and usability of casement and patio windows. Accurate measurement of spindle length and handle centres is essential when replacing or installing handles to ensure smooth operation and proper engagement with the locking mechanism. This article provides practical, actionable guidance for homeowners and tradespeople to measure correctly and select the right replacement.

Understanding the key measurements

Three measurements determine compatibility: spindle length, spindle thickness (or square size), and the centre-to-centre distance (often shortened to “centres”) between the fixing screws and the spindle. For locking handles, attention must also be paid to the direction of operation (left- or right-handed) and whether the lock is integrated into the handle or operates through a separate mechanism.

• Spindle length: the distance the square bar protrudes from the back of the handle through the window lock mechanism. Measured in millimetres from the base of the handle rose to the end of the square.
• Spindle thickness: commonly 7mm (9mm for some older or specialist gear). Most modern handles use 7mm square spindles.
• Centres: the distance from the spindle centre to the centre of the fixing screw or first screw hole used to attach the handle. Common centres are 43mm and 92mm for espagnolette and multipoint systems, but cockspur and locking casement handles may use other measurements.

Tools and preparation

Essential tools:

• Tape measure or ruler graduated in millimetres
• Vernier calipers (for precise spindle thickness)
• Phillips or flat screwdriver (to remove old handle)
• Notebook and pen or smartphone to photograph the old arrangement

Safely remove the old handle with the window in a closed and secured position. Take photographs of the backplate and lock mechanism for reference. For handles with an integrated cylinder, note whether the cylinder is removable (retained by a screw) or fixed.

Measuring spindle length correctly

1. Remove the handle from the window if possible. This provides the most accurate reading. 2. With the handle removed, measure from the face of the rose (the part that sits against the window frame) to the end of the square spindle. Record this measurement in millimetres. 3. If removal is not practical, measure from the face of the visible handle backplate to the end of the spindle while gripping the handle to avoid it turning. Note that measurements taken without removal may be less precise. 4. Add a small allowance (2–3mm) if the replacement handle has a thicker rose or backplate to ensure the spindle engages fully into the gearbox.

Most common spindle lengths for window handles with locks are 35mm and 45mm, but windows with thicker frames or additional locking furniture will require longer spindles. Where exact matching becomes difficult, a longer spindle can be trimmed, but this requires precision and care.

Measuring centres and fixing positions

For locking handles, the centres measurement often relates to the distance between the spindle axis and the screw used to secure the handle. To measure centres:

1. With the handle removed, measure from the centre of the spindle hole to the centre of the nearest screw hole used to fix the handle. 2. For backplate-style handles, measure between the two fixing holes if applicable. 3. Note whether the handle uses a single screw or two fixing screws; this affects available replacement options.

Common centres for casement handles are 43mm and 92mm, but there are many variations. Accurate measurement avoids misalignment of the spindle with the gearbox and prevents stress on the mechanism.

Determining handedness and locking type

Identify whether the handle is left- or right-handed by observing which way the window opens when the handle is operated. Also note whether the lock is:

• Push-button: requires depressing a button before turning
• Keyed: cylinder integrated into the handle requiring a key
• Snib: small catch to hold handle position without a key

When replacing with a handle such as the TSS Cockspur Window Handles, confirm the handle’s handedness and that the spindle length and centres match the espagnolette gearbox. For traditional cockspur mechanisms, the TSS Cockspur Window Handle suits older timber frames, while modern keyed solutions like the TSS Offset UPVC Window Handles provide higher security for PVCu and composite windows.

Fitting considerations and adjustments

• Ensure the replacement spindle engages fully into the gearbox. Partial engagement can cause stripping or failure.
• If the spindle is too long, it can be cut back with a hacksaw and deburred; ensure the cut is square to maintain smooth operation.
• If the centres do not match, backplate adaptors or universal fitting kits may resolve small discrepancies.
• Tighten fixing screws evenly, avoiding over-torquing which can warp the backplate and misalign the spindle.
• After fitting, test the handle through several open/close cycles to verify smoothness and that the lock operates correctly.

Security and maintenance tips

Window handles with locks contribute significantly to overall home security. Choose handles that meet recognised standards and are suitable for the window type. Keyed handles add a robust deterrent against forced opening, while push-button variants may be sufficient for internal or less vulnerable locations.

Maintenance recommendations:

• Lubricate the spindle and gearbox with a light machine oil annually.
• Check and tighten screws periodically.
• Replace worn spindles or stripped gears promptly to avoid compromising the locking function.

Troubleshooting common problems

• Handle spins freely: likely a stripped gearbox or insufficient spindle engagement. Replace gearbox or ensure correct spindle length.
• Handle stiff to operate: check for debris in the mechanism, corroded parts, or misalignment from over-tightening.
• Key won’t turn: cylinder may be jammed or misaligned; remove handle and inspect cylinder retention screw and position.

Accurate measurement of spindle length and centres prevents most fitting issues and ensures the chosen handle operates as intended. For further guidance on selecting the right style and size, consult detailed resources and fitting guides.

Window Handles Guide