Its a mostly simple job to fit a new lock barrel. The lock itself is
not replaced, just the barrel, which is bought separately.
Apart from the obvious:
A new lock barrel is under £2 for a basic one, or £4-5 for one with
hardened pins in 2011. So replacement is often cheaper than copying
keys. New bzrrels usually come with 3 keys, sometimes 2.
When moving into a house, you've no idea who has keys. Its prudent to
replace external lock barrels.
Some house insurance policies are invalid if a barrel with unhardened
pins is used on an external door.
If you're locked out and can't get in any other way, drilling out the
lock barrel is usually the easiest way to gain entry. Expect to ruin a
few drill bits in the process. 4mm twist drills are good for the job,
though if not careful more drill bits will be needed.
There are 2 ways cylinder locks are commonly fixed to doors. Remove
the visible screwheads, and either the whole lock will come off in one
piece, or most of it will come off, leaving a backplate behind that
needs to be unscrewed to remove it.
==Remove old barrel==
As you'll see, the lock barrel is held with 2 screws. Remove these and
the barrel, the ring on the front, and the plate on the rear come
away. Reuse these screws if they're not wrecked, its easier than
cutting the new ones to length.
==The new lock barrel==
They're standardised, so the main choices are brass or chrome finish,
and hardened or unhardened pins.
* minimum cost barrels are unhardened, and can be drilled open
house insurance often requires hardened pins
* hardened pin barrels can be drilled, but its more difficult, and can
take a while, and several drill bits.
unhardened may be preferable for internal rooms & cupboards, a fair
bit easier to remove if keys are ever lost.
Its not best practice to have new locks, barrels or keys posted to
you, the seller usually has your address, either from the delivery
address or credit card details, and there are people that copy keys
and misuse them.
==Fit new barrel==
How it fits in is fairly obvious, ring at the front, plate at the
back. Get the new barrel in the right position, not twisted round out
of place. There's usually a slight ring indentation in the door, you
sit the front ring in that to avoid a minor decorating mishap. Often
the old front ring looks better than the new one, and on occasion the
old rear plate is the only one that will sit flat enough.
Reuse the old barrel fixing screws when possible, it avoids needing to
cut the new ones. If they can't be reused, the new ones can be chopped
or sawn at the indentations. Don't try to snap them by bending, a lot
of these screws aren't hardened and will bend, ruining them instantly.
The tongue of the new barrel needs to be cut to length. Mark on the
tongue where it projects about half the depth of the lock, and cut it
off there. Length needn't be precise. A hacksaw works, but is slow and
fiddly; bolt croppers or mini bolt croppers are very quick.
Just the reverse of removing it.
Issues sometimes encountered:
The new lock is too stiff to turn as far as is needed. If it turns in
one direction ok, and opens the lock, no problem. If not, slacken the
lock barrel fixing and slide it sideways a fraction so it lines up
better with the slot in the lock, and retighten.
The lock screws won't tighten because the thread in the wood is
stripped. Probably the simplest solution is to lightly hammer a
matchstick into the hole in the wood door, and snap it off level. Or
sometimes slightly fatter screws will fit and grip. Or if the screws
are short, fit long ones.
Lock won't quite sit flat against the door. This happens when the rear
plate that holds the lock barrel fouls the lock. Loosen this
backplate, reposition slightly and tighten, or remove it and put the
old one back on instead.
In some situations you might need the new lock to take the old key.
Rekeying a lock barrel is a locksmith's job.
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