LOCK AND LATCH REPAIRS
Locks and latches are a vital part of your home’s security, so it’s important to keep them in good working order. But if they fail, don’t worry — it’s not difficult to make effective repairs.
REPLACING DAMAGED LEVERS
Although some patterns of mortise have a cylinder mechanism, most use a lever system. This can be replaced — either to repair a damaged lock or to alter the combination. The lever mechanism is contained within the body of the lock, so you must first remove the lock completely and then dismantle it to gain access to the levers.
Removing a mortise lock requires care and patience. If your lock has a double fore end, there’ll be a decorative plate covering the body of the lock itself and you’ll have to remove this outer one before you can get at the fixing screws securing the lock in the mortise. If the lock has been correctly fitted, it will still sit fairly tightly in the door after the removal of these screws. If your lock has a latch operated by a handle, you need to remove the handles and the operating bar which passes through the lock.
If your lock has a hole to take a square bar for the handles, insert a screwdriver until it emerges on the other side. Gripping both ends, you should then be able to pull the lock about 6mm out of the mortise.
If your lock has no follower, insert a screwdriver carefully into the key hole and gently push the lock out of the mortise.
Once you can fit the blade of a screwdriver under the fore end, do so at both top and bottom and ease the lock out until you can out completely.
1. With the lock free from the mortise, remove the cover plate on a flat surface and make sure no parts are disturbed. Take note of the position of any loose parts.
2. Levers have a set order in the lock. Take note of it otherwise you risk ruining your lock.
3. On inspecting the mechanism you might well find that a lever spring has broken or that a lever itself has worn out. You may be able to replace just the spring, but usually you have to replace the lever as well.
You’ll be able to get a replacement from a locksmith but you’ll have to tell him the make of lock and its type. Unless it’s actually broken, it’s best to take the lever with you. If you can’t get an exact replacement another one will do. But you will have to get a new key cut. Another option is to replace all the levers together.
Each lever fits on the pivot with its spring tight up against the stump. When the bolt is in the locked position, the bolt stump will sit in the lever pocket furthest from the lever eye. Un blocking it will pull the stump through the gate into the pocket close to the eye.
4. Lift the levers off the pivot and remove the damaged one.
Replace them in the correct order. Then replace the plate. Test the lock several times and refit it in the mortise.
Before reassembly, moving parts should be lightly greased.
As a rule, locks should be lubricated twice a year. On most locks a thin all similar to that used on bicycles will suffice. Cylinder locks, however, must he lubricated with powdered graphite from locksmiths.
Insert the nozzle of the container in the cylinder and squeeze to deliver the graphite. Or apply the graphite to a key and insert it in the cylinder.
If you can’t manage to obtain any powdered graphite, simply rub a pencil point along the key and slip it into the cylinder.
If your mortise lock is stiff you should oil each side of the bolts and also the pin and nose of the key. Then simply lock and unlock it several times. Remember, the lock mechanism is often above the key hole so if you’re squirting in oil or graphite, point the nozzle upwards.
Oil the latch of a night rim latch, graphite the cylinder and then turn the interior handle several times. Finally, if the lock is still sticking it will have to be removed from the door, dismant led and cleaned with petrol.
FITTING A NEW CYLINDER
Night latches, as well as some patterns of mortise lock. Are operated by a cylinder mechanism. These don’t often go wrong, but there may well be occasions when you have to replace one. If you lose your keys, for example, you might find it more economic to replace just the cylinder rather than the whole lock. If you somehow manage to snap off the shaft of your key while it’s in the lock, it’ll be difficult to get it out without a special lock smith’s extractor tool as it will be firmly gripped by the spring lock tumblers. The plug of a
cylinder could well get damaged if the wrong key has been in serted and force applied. Replacing the plug of a cylinder is not an easy home repair, but the next best step, replacing the cylinder, certainly is.
1. How you remove the damaged cylinder depends on the type of lock you have. On a rim nightlatch, start by removing the latch case from the inside of the door. It will usually be secured in place by three or four screws.
Lift the case away to expose the backplate and the thrower (connecting bar) that runs
through the door from the cylinder to the latch case.
2. Loosen the cylinder by removing the set screws at the bottom of the central hole in the backplate. These screws run through the door and into the holes on each side of the cylinder. You can then push the thrower towards the outside of the door to dislodge the cylinder.
If necessary, remove any fixing screws on the backplate so that you’re left with a door free of hardware.
3. You’ll have to cut the new thrower bar to match the old.
To fit the new cylinder simply reverse the removal procedure.
REMOVING A BROKEN KEY
Cylinder keys are prone to breaking if they are bent or if excessive force is applied. The break almost invariably occurs at the first cutout for the pin tumblers — especially if this is deep.
For this reason, it’s unwise to continue using a key that’s been accidentally bent and then straightened. And if the lock is stiff to operate, you should lubricate it or replace the cylinder as necessary.
If you do break a key in the lock, you can sometimes remove the stub with a very fine pair of longnosed pliers. But more often than not. The stub will be too short to grip and the lock’s spring pressure will hold it securely.
1. In this case. Remove the cylinder. The thrower bar which operates the latch mechanism is retained on the back of the cylinder by a circlip. Prise this free, taking care not to lose it as it springs tree.
2. Remove the thrower bar. This will expose the end of the cylinder.
3. It should now be possible to push out the broken key with a fine piece of stiff wire.
Lubricate the cylinder while you have it out. Reassemble the cylinder mechanism and refit the lock on the door.
1. Remove the cylinder mechanism from the door. Prise free the circlip which retains the thrower bar
2. Remove the thrower bar to gain access to the end of the cylinder mechanism
3. Push out the broken part of the key using a piece of stiff wire.
4. Refit the cylinder and reassemble the latch