Replacing Window Handles: Spindle Length and Screw Centres Explained

Replacing window handles is a common maintenance job that keeps windows secure and easy to operate. Correctly matching spindle length and screw centres is the most important factor when fitting a replacement handle: the wrong dimensions cause loose fittings, poor operation or even damage to the locking mechanism. This guide explains how to measure accurately, choose the right replacement, and fit new handles for a neat, functional result.

Understanding the key dimensions

Two measurements determine compatibility for most window handles:

• Spindle length: the square bar that connects the handle to the locking mechanism. It is usually 7 mm square on modern handles but varies in length.
• Screw centres: the distance between the centres of the fixing screws on the handle backplate, measured in millimetres.

Additional considerations include handle type (espagnolette, cockspur, or cranked), the projection of the spindle relative to the backplate, and whether the handle is handed (left or right).

Common spindle lengths encountered in domestic windows are 35 mm and 44 mm, measured from the face of the handle backplate to the end of the square spindle. Some older or specialised systems use 25 mm, 30 mm or longer spindles. Standard screw centres are frequently 43 mm for casement espagnolette handles and 48 mm for some types of cockspur, but always measure rather than assume.

How to measure spindle length and screw centres

Tools required: tape measure or ruler, vernier calipers (if available), Phillips or flat screwdriver, pen and paper.

1. Remove the existing handle: - For most handles, loosen the two fixing screws and withdraw the handle. For some handles the screws are concealed beneath a cover cap—prise these off gently with a screwdriver nib. 2. Measure the spindle: - Measure from the face of the backplate (the point where the handle sits flush against the frame) to the end of the square spindle. Record the length in millimetres. If the spindle is broken or worn, measure the length remaining and inspect the lock mechanism to ensure it is undamaged. 3. Measure the screw centres: - Measure centre-to-centre between the two screw holes on the backplate. It is best to measure across the face of the plate, taking the midpoint of each screw hole. 4. Note handedness and type: - Determine whether the handle is left- or right-handed by looking at the orientation of the handle when closed. Identify whether it is espag (operates an espagnolette locking rod), cockspur (a lever that bears against the frame), or another type.

Record these three values: spindle length, screw centre, and handle type. These allow confident selection of a replacement.

Choosing the correct replacement handle

Purchase a handle that matches the spindle square size and length, the screw centres, and the handle type. Examples of suitable options for common applications include the espagnolette style TSS Cockspur Window Handles for modern uPVC casement windows, the traditional TSS Cockspur Window Handle for timber or older uPVC windows, and the robust TSS Offset UPVC Window Handles for frequent-use situations.

If exact measurements are not available, select an adjustable or universal handle where possible—some espag handles accept replaceable spindles or offer a spindle adaptor. Avoid cutting spindles down without ensuring the resulting length still engages the locking mechanism sufficiently.

Practical fitting steps

Tools required: screwdriver, replacement handle, possible secondary screwdriver or hex key for grub screw, threadlocker (optional), light lubricant.

1. Prepare the window: ensure the espagnolette rod or locking mechanism is in the closed position so the spindle aligns correctly with the lock. 2. Fit the spindle: push the spindle fully into the lock. If the spindle is longer than required, remove the handle and shorten the spindle only if the manufacturer permits; otherwise obtain the correct length. 3. Position the handle: align the fixing holes with the drilled screw positions on the frame. For handles with a centre-boss, ensure it locates over the lock spindle without forcing. 4. Secure screws evenly: tighten screws alternately to prevent the backplate skewing. Do not overtighten as this can strip screw threads in uPVC frames; screws should be firm but not bulging the backplate. 5. Check operation: cycle the handle through its range to confirm smooth engagement of lock points. If stiff, check spindle alignment and apply a light smear of lubricant to moving parts. Confirm the handle returns to the closed position without catching. 6. Final checks: ensure handle is square and level, and that the locking engages exactly at the same handle positions as before.

Common problems and solutions

• Loose handle after fitting: likely incorrect spindle length or stripped frame threads. Verify spindle length and replace screws with slightly longer ones or use a nylon plug for damaged holes.
• Handle spins without operating lock: the spindle may be worn (rounded) or the backplate incorrectly seated. Replace spindle or handle, ensuring the spindle engagement depth is correct.
• Handle too short to engage: obtain the correct spindle length; do not rely on packing with washers as this can misalign the handle and stress the lock.
• Screws do not match holes: a new handle may have different screw centres. Either source a handle with matching centres, drill new holes carefully, or use a universal backplate where available.

When to replace rather than repair

Replace handles when:

• The spindle or square is rounded or fractured.
• The backplate is cracked or bent.
• Security upgrades are required (e.g. to a child-safety or anti-snap option).
• Repeated repairs are needed due to wear.

Replacing window handles is a cost-effective way to restore smooth operation and security. Accurate measurement of spindle length and screw centres, paired with the correct handle type, ensures a successful installation with minimal fuss.

Window Handles Guide