The maintenance team at a school in Twickenham got in touch because they wanted one of the door cylinders changed from a key-and-key lock to a key-and-thumb-turn version.
Once on site, I removed the existing cylinder to take accurate measurements. That exposed another issue: the lock had snap protection, but it had been fitted the wrong way round, with the protected side facing inward. That rather defeats the point of having the protection in the first place.
I did not have the exact thumb-turn size required in van stock, so I ordered the correct cylinder directly from the manufacturer along with the extra keys the school needed.
Thumb-turn cylinders are one of the reasons carrying every possible lock size is unrealistic. Unlike many key-and-key cylinders, which can normally be fitted either way round, the internal and external sides of a thumb-turn lock matter. Add the different security specifications and dimensions and it does not take long before you would need a truck rather than a van.
Once the correct cylinder arrived, I returned and installed the properly specified lock with the security side facing the right way this time. The school had the thumb-turn operation it wanted without compromising the cylinder’s intended protection.
