7 Tips for Fitting a Mortice Lock

If you are wondering how to fit a mortice lock, you have come to the right place! To make your DIY task that little bit simpler, we have put together our top seven tips for fitting a mortice lock. These seven tips are for anyone who is about to install a key operated lock to an internal door such as a bedroom, study, or closet door where additional security is required.


Tip 1 IconMeasure to fit

Look at the width of the door stile and thickness of the door before ordering a mortice lock. Lock bodies come in several different thicknesses and lengths to suit interior doors. We offer two sizes which includes a 63mm width with a 45mm backset, and a 76mm width with a 57mm backset. Our key locks are suitable for fitting to both new and existing doors.


Tip 2 IconMark the keyhole

When you have cut the mortice, hold the lock body against the face of the door so you can mark the position of the keyhole on it with a bradawl or pencil.


Tip 3 IconBe careful when drilling

This tip will help you determine when to stop drilling! Drilling too deeply into the door stile can weaken the internal door. To avoid this, wrap some tape round your drill bit so you can see when you have drilled holes to the required depth. The correct depth is a fraction more than the length of the lock body. If your drill has a depth guide or stop attachment, you can use that instead.


Tip 4 IconDon’t split your sides

Choose a drill bit that is just a fraction wider than the thickness of the lock body. If you create a wider mortice, you will weaken the door which could split around the lock if forced.


3 Lever Mortice Sash Lock 76mm / 57mm Polished Brass



Tip 5 IconShield your eyes

Although we recommend wearing eye protection for this DIY task, we understand that you may not have that available. Resist the temptation to the blow the loose shavings out of the mortice. Instead, pull out the shavings with the drill bit or use a vacuum.


Tip 6 IconGetting a firm grip

Turn the key to extend the bolt of the lock before you insert it in the mortice to test the fit. If it jams you can then grip the bolt and pull the lock body out with ease.


Tip 7 IconMeasure up for a perfect fit

With the lock fitted, use a ruler to measure the distance between the bolt and the closing face of the door. Use this measurement to position the keep plate on the door frame so that the bolt just engages when the door is locked.


For ease of installation, our 3 lever mortice locks are supplied with a front plate, keep plate and the screws required. Two keys are also supplied and are 3 lever mortice locks are suitable for use with standard 8mm spindles. Our range of mortice locks feature various finishes, including matte black, copper, polished brass, and satin stainless steel to suit all interiors and offer a cohesive fit with our wide range of matching door furniture and accessories.


Now go forth and tackle your DIY installation with our seven tips for fitting a mortice lock! We hope to inspire your home improvement projects and offer a variety of high-quality products that excel in both aesthetic and performance. If you love all things interiors and style, check out our previous blogs and be sure to visit our Pinterest for more inspiration!