The cylinder holds the secret, the lock holds the mechanism
A change of tenant, a key lost somewhere on the hill, a spare still in circulation from the previous occupier: in the Demi-Lune blocks these are cylinder jobs. One screw on the edge of the leaf releases it, and neither the case nor the multipoint rods are touched. The new cylinder takes up the existing backset, and the old keys stop working as soon as the job is done.
A complete replacement is called for when the mechanism itself fails: a bolt that no longer throws, bent rods on a multipoint, a faceplate pulling out of the timber. On the older landing doors of the avenue Charles de Gaulle blocks, that is settled by opening the door and looking at the case, not from a photograph: the face you see from the landing says nothing about what is buried in the leaf.
Between the two sits a case that is common in Le Bourg. The lock works, but it strains because a solid timber leaf has moved inside a frame bedded into stone. Fitting a new mechanism without correcting the alignment simply subjects it to exactly the same load. The hinges and the keep are adjusted first, and the model is chosen afterwards.
What the door and the building impose on the choice
Old joinery in Le Bourg will not take just anything. The backset, the thickness of the leaf and the depth of the mortice were cut for the original lock, and some of these village-house doors fall outside the sizes stocked by suppliers. Measurements are taken before a part is ordered, and two neighbouring doors on the same street sometimes call for two different references.
In the Demi-Lune blocks, the appearance of the door seen from the shared landing is usually covered by the co-ownership rules. Changing a cylinder raises no question at all; replacing a lock in a way that alters the outward face of the leaf is checked with the syndic beforehand, not afterwards. The same applies to a handle or a plate visible from the stairwell.
At Alaï, Le Méginand and Vaubonne, the front door is only one way in among several. Motorised gate, side gate, garage door, service door onto the garden: where all of them hang on the same keyring, changing a single cylinder deals with only part of the problem.
How does this service work?
Techniques, typical situations, standards and things to watch out for: it is all on our lock and cylinder replacement page. This page focuses on what the service involves in Tassin-la-Demi-Lune.