Charting a suite for eleven doors, and the one we left out

Eleven doors, one manager, four supervisors, nine staff. The brief was the one every suite starts with: one key that opens everything, and everyone else carries as few as possible.

The chart is the job

Pinning takes an afternoon. Deciding takes a week, because the chart is really an argument about who is trusted with what, and nobody enjoys writing that down. We ask for the door schedule and then ask four questions per door: who must reach this, who must not, what is behind it at three in the morning, and what happens if this key turns up in a taxi.

For this unit that produced a grand master, two sub-masters — front-of-house and stores — and eleven change keys.

Every wafer doubles something

A mastered chamber has a brass wafer between the key pin and the driver, so it has two joints and two cut depths open it. That is what lets the grand master turn every cylinder. It is also what people forget: with six chambers, each mastered chamber doubles the number of bittings that will turn that lock. Master all six and 64 different keys open it, most of which you never cut and any of which somebody else might already carry.

So we master as few positions per cylinder as the chart allows. On this suite that was two, and on the front entrance, three.

The door we left out

The server cupboard. It is on the same blank, it sits in the same corridor, and it is not on the chart. No wafers, one joint, one key — and the grand master, which is cut deeper at the mastered positions, leaves a driver pin across the shear line and does not turn.

That is a design decision that looks like an oversight until you need it. The manager’s key opens the building; it does not open the cupboard with the client data in it, and no argument at eleven at night can change that, because the answer is brass.

What it cost

£28 a cylinder for eleven cylinders, plus a one-off design fee against the door schedule. Three weeks from schedule to fitting, most of which was waiting on the restricted blanks.