step by step guide to.. Replacing a cylinder rim lock.
Sometimes they jam due to wear and tear of the inside parts and the easiest solution is to replace the full lock.
Or you may need to replace it simply because you have lost your keys.
The lock is made of a cylinder that fits through a hole drilled in the door, with the lock body attached to the door inside. It locks in to a staple fitted to the door frame.
A cylinder lock does not offer the same security as a mortise lock, which fits into a slot cut in the edge of the door. It can be easily forced as it is only as strong as the screws that hold it to the door. But it will secure your door while you are in the house.
Its mechanism allows the lock to be opened by a key from the outside and a snib or knob allows the door to be opened from the inside.
So you don't have to fumble about with keys like a jailer when the postman or a friend calls - all you need to do is turn the knob to open the door from the inside.
Here's what you'll need..
Measure the centre point of the cylinder - usually 60mm from the edge of the door - so the new lock will be identical to the one being replaced.
Remove the existing lock by unscrewing its body on the inside of the door. Remove the cylinder and the staple from the doorframe.
The old screws may have weakened the recess in the doorframe, giving the new ones nothing to grab. Hold the 6mm plywood to recess and note thickness on the frame.
Chisel out the damaged wood from the recess so you have a fresh flat surface.
Cut the plywood to fit into the recess using the staple as a guide and use wood glue to secure it. Wipe excess glue with damp cloth. The new screws will catch on to this surface.
Use a palm sander to flush the edge of the plywood in line with the doorframe, giving a perfect surface for the staple.
Fit the cylinder into the door hole. Secure the back plate, which holds the cylinder firmly in the hole.
Fit the body of the lock on to the connecting bar of the cylinder and secure the lock to the door by inserting the fixing screws.
Hold the lock's staple into the recess in the doorframe and drill pilot holes for the screws. Fix the staple in position with the screws.
Donny's top tip: Fill any old screw holes with Unibond interior frame sealant.