Locksmithing and Security

“Snib” is a more correct term for what is often known as the latch button on a latch lock.

A latch lock is the kind that can slam shut behind you, locking you out. Usually when you’ve decided to nip quickly out onto the doorstep in your dressing gown in order to get the milk delivery.

The snib is the little button that locks the latch bolt in the open position, and sometimes in the closed position as well. There are at least two reasons for checking that the snib isn’t loose.

Firstly if you have a dog (or cat?) that has the habit of jumping up and pawing at the locks, then Fido just might manage to activate a loose snib and lock you out.

This has now happened twice to one of my customers. They didn’t believe me the first time and wouldn’t let me change the lock. Now they are believers.

Secondly, if a snib has become loose and the lock is a “nightlatch” style lock on the “dangerous” side of the door (for a Yale 77, 84, 85, 88 or 89, for example, the “dangerous” side is the left as you look from the inside) then slamming the door could cause the snib to drop and lock you out — if down is the locking direction. (When mounted on the other side of the door a dropping snib is dropping towards the open and safe position.)

My goodness, there are some stupendously incompetent cowboys about.

Yale’s top-end domestice rimlatch is the PBS. It’s British Standard rated. That’s not easy to achieve in a rimlatch. Yale have gone to a lot of trouble to make it strong and secure. And you will be paying a lot of money if you buy one.

All of the components contribute to its strength, it’s security and to its BS rating. Omit one of those components and the BS rating is invalidated.

I’ve just been to change a PBS-1’s cylinder. Whoever fitted the lock originally hadn’t bothered with the pesky bolts that secure the escutcheon to the door (the escutcheon is what surrounds the keyway); I guess it was too much effort to drill two more holes of just the right size hole in just the right place. They hadn’t bothered with the anti-drill spin plate covering the cylinder plug; I guess they dropped it and couldn’t be bothered looking for it. They hadn’t bothered with the hardened clip that prevents the cylinder retaining screws being attacked; “Duh. What’s this? Oh it comes off. Can’t see what that’s for. Bin it.”

So the customer had paid £100 for a lock (and goodness knows how much the “fitter” demanded) that was hardly any more secure than a £30 lock. And if a BS-rated rimlatch had been a requirement of their insurance policy, then their insurance company would easily have wriggled out of paying any break-in claim.

What is a dropped snib? Is it one of the many ailments that torment us over-fifties?

Snib or holdback are the correct terms for the part of a lock that stops a door latching behind you as you pop out to the dustbin in your dressing gown. It’s often incorrectly called the latch; latch, however, is what a door is doing if it locks as it closes, without your having to take any action other than close the door.

On locks that don’t have much sophistication, as well as holding the latchbolt open, the snib can also lock the latchbolt closed even against the correct key.

A dropped snib is when the snib gets loose, and when the lock is fitted to the unlucky side of the door, and when as you slam the door and it latches shut, the snib falls down and locks you out.

So, which way would your snib be going if it fell downwards? Would it be falling towards inactive? Nice green tick! Or falling towards active? Nasty red cross! If, for example, you had a Yale rimlatch lock on the right-hand side of your door (looking at the door from the outside), then I’m afraid it doesn’t fail safe, it fails the vexatious way.

If you have a simple latch lock and it’s on troublesome side of the door, keep an eye out for the snib getting loose and floppy.

If you like finding things to worry about, I have one more for you. Is there a big gap between the door and the frame? It has been known for a latch lock to be snibbed to the locked state while the door is actually open, and then for the door to slam shut. The gap is big enough that the bevelled latch bolt can enter the bolthole, but it can’t then be got out again.

Even one of the locksmith bulletin boards I’m on can’t get this one right!

A rim lock is one that is fixed to the inside face of the door. (Although it would not surprise me if one of the national call centres’ operatives, whose work I was tidying up after yesterday, had fitted a rimlock to the outside face of a door! Remember: the nationals are good at advertising and staffing call centres in a “cost effective way”; they are not good at locksmithing, plumbing, carpentry, …)

The alternative to a rim lock is a mortice lock. This is one that has been fitted into a chiseled-out hole (the mortice) in the door. As long as the door’s thickness is 44 mm or more, a mortice lock is usually more secure.

A different kind of classification (and this is where even my trade association’s bulletin board gets it wrong), is the way in which the lock works: most often the tumblers are either pins or they are levers. And normally pin tumblers are fiddly and small enough that they are encased in a, usually removable, cylinder. So pin tumbler locks can usually also be called cylinder locks.

The most common pin tumbler cylinder lock on wooden doors in the UK is the five-pin Yale. The most common mortice lock in London is the Chubb 114, which is a five-lever mortice lock.

Often, but definitely not always, a pin tumbler/cylinder lock is a rimlock and a lever lock is a mortice lock.

Well, if you care, hopefully that’s been of help.

Oh. Back, briefly, to the nationals. They are the ones with the huge adverts in the phone books where there are no local phone numbers visible. Naturally, I am going to say that 90% of the time, you’d be better off with a local tradesman (I wish I could say 99%, but there we are; I’d also like a Goldwing for Christmas). And if you are a local tradesman who’s kindly offered an 0800 or 0845 number, my advice would be to show your landline number as well, so that people can have confidence that you are local.