The labels “7.5 mm” and “19 mm” do not identify a complete espag lock. They can describe different dimensions in different catalogues, so a correct selection requires a measurement drawing, profile compatibility check, and test assembly. By the end, you will know what to measure, which locking features to compare, and what to specify for a Bangalore installation or replacement.
Key takeaways
- Measure spindle size, backset, faceplate and locking-point spacing separately.
- Match the lock to the window profile, groove and sash dimensions.
- Choose locking points after checking sash size, compression and security needs.
- Test handle movement, seal compression and every locking point on site.
What 7.5 mm and 19 mm Actually Measure
A catalogue’s 7.5 mm usually identifies the square spindle size: the width across the metal spindle entering the handle follower. It is not the backset, faceplate width, groove width or sash-rebate dimension.
The label 19 mm is ambiguous. It may mean a 19 mm backset, measured from the faceplate edge contacting the sash to the centreline of the spindle follower, or a 19 mm faceplate width. These are different measurements, so 7.5 mm and 19 mm cannot be compared without a dimensioned drawing.
sash channel ┌──────────────────────────┐ │ ○ fixing hole │ │ │ faceplate │ │ │ ───── square spindle ─────▶ handle │ │ ↑ │ │ │ spindle follower centreline │ │◄──────┘ │ │ 19 mm backset │ ○ fixing hole └──┴─────────────────────────┘ ↑ faceplate edge contacting sash ↕ faceplate width
Measure the backset from the faceplate edge, not from a decorative handle cover. Do not measure to the centre of a fixing screw; that can create a false 19 mm selection. The sash channel is the profile’s hardware recess, not automatically the backset or sash rebate.
Require the supplier drawing to define spindle size, backset, faceplate width and fixing-hole centres. “7.5/19 espag” is espag terminology, not a complete specification of the lock’s dimensions.
How to Measure an Existing Espag Lock Before Ordering
Record the existing lock before removing it. Matching overall length alone fails when cam positions, handle height or gearbox location differ; the replacement rods then miss the keeps or the handle cut-out.
| Record type | What to capture | Why it matters |
|---|---|---|
| New installation | Profile channel width and depth, sash rebate, handle height, keep layout and required rod length | Confirms the lock fits the profile and frame |
| Replacement | Every dimension below, plus photographs of the installed lock | Preserves existing cam, screw and handle alignment |
- Take the backset measurement from the faceplate edge to the spindle-follower centreline.
- Measure spindle height from the sash edge or reference corner to the spindle centre.
- Record gearbox case dimensions: width and height, including its position from the sash end.
- Measure lock-strip or faceplate height, width and thickness.
- Record centre distance from the spindle centre to every locking point.
- Mark each mushroom-cam position from the sash end and note its adjustment range.
- Measure each shootbolt length and the overall faceplate and rod length.
- Measure fixing-hole centres, including end offsets and repeated spacing.
- Draw the sash cross-section, showing the hardware channel, rebate and faceplate position.
- Mark every keep location and its locking-point type on the keep layout.
Send a ruler-scale face photograph, end photograph and handle-side photograph. Add the sash cross-section, keep layout and a dimensioned drawing. Label spindle size, backset measurement, spindle height and gearbox case dimensions; “7.5/19 espag” is not an auditable replacement specification.
How to Confirm the Lock Belongs in Your Window System
An espagnolette lock has one central gearbox that turns drive rods carrying several cams along the sash edge. A matching lock must suit the profile groove dimensions, not just the advertised backset or length.
| Hardware | What you will see | What it does |
|---|---|---|
| Espag | Gearbox, rods and multiple cams | Locks one sash at several frame points |
| Mortise lock | Single case with latch and deadbolt | Locks through a door-style strike |
| Sliding-window bearing | Roller or bearing assembly | Guides a sliding sash; it is not a lock |
| Domal bearing | Profile-specific roller or guide unit | Supports or guides a Domal-type sliding system |
| Multipoint door lock | Long strip with hooks, rollers or bolts | Secures a door at several points |
| Cockspur or casement handle | Handle with spur, wedge or simple spindle | Clamps or operates a local latch, not espag rods |
For aluminium window espag compatibility or a uPVC espag lock, check every item before ordering:
- Confirm aluminium or uPVC profile, then measure the hardware-channel width and depth.
- Check sash rebate, edge clearance and the faceplate position inside the groove.
- Match handle type, handle cut-out height and screw-hole spacing.
- Verify the 7 mm versus 7.5 mm spindle, including the follower centreline.
- Match lock length, gearbox position and the installed keep pattern.
- Confirm cams provide seal compression without excessive handle torque.
- Check end-user access: handle reach, key access and unobstructed operation.
A mechanically matching lock still fails when its spindle centre misses the handle cut-out, or its cams meet no keeps. The same warning applies when rods fit the groove but leave insufficient clearance at the sash rebate.
Choosing Locking Points for Profile, Size and Security
A 7.5 mm or 19 mm label does not select the lock by itself. Match the profile channel and sash depth first, then confirm handle height, opening size, gearbox position and the keep layout on the frame. A correct spindle or backset still fails when the cams land beside the keeps.
| Locking point | Main advantage | Check before selection |
|---|---|---|
| Roller cams | Simple engagement and adjustable compression | Confirm compression adjustment and weather-seal contact |
| Mushroom cams | Better resistance to lifting and forced operation damage | Match mushroom shape and height to the keeps |
| Hooks and shootbolts | Strong positive engagement for larger or taller shutters | Confirm keep depth, travel and correct engagement |
| Shootbolts | Useful at top and bottom of tall sashes | Provide rod support and check that bolts cannot foul |
Point count alone proves little. Distribute cams along a tall shutter, add intermediate rod guides where the profile requires them, and check that long rods do not bow or stop short of full engagement. Choose reversible operation only when the gearbox and keeps permit it; otherwise specify the correct handed version.
Too much seal compression creates high handle torque, gearbox wear and premature failure. Too little causes rattling, air leakage and water entry.
A key-locking handle only blocks handle rotation. It does not replace engaged cams, sound keeps, profile reinforcement or correct screw fixing, so test the complete assembly rather than treating the key as the security system.
From Selection to Site Test: A Bangalore Project Specification
Freeze the aluminium or uPVC profile before selecting an espag. Record sash rebate, channel, handle height, backset, faceplate width, gearbox position, rod length, fixing-hole centres, and every locking-point position; matching overall length alone leaves cams outside the keeps.
| Stage | New fabrication | Replacement |
|---|---|---|
| Profile record | Confirm profile, sash, seals, hinges and drainage | Photograph the installed profile and existing keep layout |
| Lock record | Set handle height, rod length and cam positions | Measure spindle centre to each cam, gearbox position from sash end, faceplate length and hole centres |
| Approval | Cut rods only after geometry is corrected | Reject any sample that misses the existing handle cut-out or keeps |
Before cutting, fabricators must correct sash squareness, hinge geometry and keep alignment. Issue an espag purchase order specification that names spindle size, backset, faceplate width, rod length, fixing-hole centres, finish, handedness or reversibility, locking-point count and type, and permitted tolerances.
Require a dimensioned drawing, profile-specific compatibility confirmation and a functional sample from a profile-specific hardware supplier. Aruna Techno Industries can be evaluated on those documents and tests, not on the phrase “7.5/19 espag”.
Approve only a functional test assembly using the nominated profile, sash, lock, handle, keeps, seals and fixing screws. Operate the handle repeatedly, inspect seal compression, confirm every cam enters its keep, and check drainage paths remain open.
Specify Bangalore monsoon maintenance: inspect after wetting, remove dust before lubrication, protect finishes from solar exposure, and use only the lubricant and interval approved for that lock material. Do not lubricate exposed running surfaces with dust-attracting oil.
Frequently asked questions
What does 7.5 mm measure on an espag locking system?
It usually identifies the square spindle width entering the handle follower, not the backset, faceplate width, groove width or sash rebate.
How do you measure an existing espag lock before ordering?
Record the spindle size, backset, faceplate dimensions, overall strip length, locking-point positions and handle height from the existing lock.
How can you confirm an espag lock belongs in your window system?
Compare the lock’s faceplate, groove fit, sash dimensions, handle position, gearbox and locking-point geometry with the installed window profile.
How many locking points should a window use?
Select the number and position after checking the profile, sash size, compression requirements and project security specification rather than choosing by lock length alone.
What should you test after installing an espag lock in Bangalore?
Check smooth handle rotation, full engagement at every locking point, gasket compression, sash alignment, key operation and repeated opening and closing on site.
