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Office chairs arrive in a box and go together in half an hour, and a few points during assembly determine how long the chair stays tight.

The Order

Casters into the base first, pressed home firmly until they click. Then the gas cylinder into the base, which simply drops in and is held by the chair’s weight rather than by a fixing.

Then the mechanism onto the seat, the backrest onto the mechanism, and the seat assembly onto the cylinder last.

The cylinder is a friction fit. It looks insecure and it is correct: sitting down seats it permanently.

What Goes Wrong

• Casters not pushed fully home, which come out later under load
• Bolts tightened fully before everything is aligned
• The backrest fitted upside down, which happens more than you would think
• Washers omitted, which lets bolts work loose
• Left and right armrests swapped, so the arms angle outward

Where a manufacturer supplies spare fixings and a parts diagram, of the kind included with ranges at stellamia.org, keeping that sheet is worth more than it looks two years later.

Loose Before Tight

Assemble everything loosely, check alignment, then tighten in stages working across the piece rather than doing one bolt fully at a time.

Tightening in sequence locks in misalignment permanently.

Retighten After a Month

The maintenance step nobody does and everybody needs.

Every bolt on a chair loosens as the parts bed in, and a chair that has developed a creak or a wobble almost always has a loose seat plate rather than a broken one.

Five minutes with an Allen key once a year prevents most chair complaints.

Lubrication

Casters and the tilt mechanism benefit from a light dry lubricant occasionally. Not oil, which attracts dust and makes a paste.

A squeaking chair is usually the mechanism or a caster axle rather than anything serious.

Never Dismantle the Cylinder

A gas cylinder is a pressure vessel. Cutting, drilling or attempting to open one is dangerous and there is no reason to.

Removing one from a base is stiff work and worth looking up before attempting, and worth doing with the chair on its side.

Replacement Parts

Casters, cylinders and armrest pads are standard sizes on most chairs and cost very little.

A sinking chair is a cylinder rather than a write-off.

Keep the Allen Key

Taped inside the base, where it will be found.