Brass catches are often found on old cupboards and wardrobes, with or without a key-operated lock. The spring that holds the catch in the closed position is made of sprung steel and, sooner or later, it will fail. The catch then remains in the open (retracted) position instead of only retracting when the knob or lever on the outside is turned, and the cupboard door won't latch shut. Save money by repairing the catch instead of buying a replacement and avoid the hassle of trying to find one that is exactly the right size.
It's fairly easy to make a replacement spring from an old retractable steel rule. It may not last as long as the original one, but at least your cupboard will stay shut for a while and the cost is minimal. Cheap retractable rules can often be found in pound shops and supermarkets if you don't have an old one lying around that no longer retracts.
You will need
- An old flathead screwdriver
- An old retractable steel rule
- Round nosed pliers (or ordinary pliers and a small nail)
- Safety glasses
Step 1: Remove the Catch and Open It
Start by removing the knob or lever on the outside of the cupboard. There may be a small screw on the underside, or it may be attached to a decorative plate (escutcheon) that is screwed to the door. It's a good idea to photograph everything before you remove it in case you forget how it all goes back together again.
Once the knob is off, the square-section spindle should just pull out.
Then open the cupboard door and remove the catch mechanism from it. In most cases the catch will be surface mounted on the inside of the door, but it may be mortised into the door and only accessible from the opening edge. Either way, undo the screws holding it in place and remove it from the door.
At this point, you can test that there is nothing wrong other than a broken spring by holding the catch vertically, with the latch at the bottom. When you pop the spindle back in place and rotate it backwards and forwards, the latch should oblige by going in and out. Gravity is providing the force that the spring once did. If this doesn't work, don't despair because it may just be that pieces of broken spring are fouling the mechanism.
The next task is to disassemble the catch. You may be lucky and find that it is screwed together, but many brass catches are just held together by rectangular lugs in the cover which are a tight fit in holes in the backplate. You will need to persaude the two parts to separate by careful use of an old screwdriver as a lever. Or tap the lugs out from the backplate side.
Step 2: Find the Broken Spring
You can see how the latch mechanism is supposed to work by playing with it. When the user pulls the lever down (or turns the knob) on the outside of the door, the spindle rotates and pulls the latch back into the case, against the (missing) spring. When the user lets go, the spring pushes the latch back out again into the closed position. Hold the case with the latch downwards as before and check that this works. If it doesn't then something isn't in quite the right position, or there's a bit of broken spring jamming things up, so fiddle about until it's working properly.
Now we need to figure out what the spring should look like and make a new one. A few bits of broken metal probably dropped out when you first opened the case. If not, have a good look for them inside, and on the floor. With luck, the spring will only be in a couple of pieces and it will be easy to see what size and shape it was. Otherwise, look for the pin that the spring was attached to and for any scratches on the brass backplate that indicate where it has rubbed. Once you have figured out how the moving parts are meant to work, it should be obvious how long the spring needs to be and its approximate shape, but if you are in any doubt then bend a paperclip (see photo) and experiment. One of the legs of the spring pushes against the end of the latch while the other will push against the case, when it is re-fitted.
If your catch also has a key-operated lock, like the one in the photo, then you might as well check that the lock spring is OK and the lock still works. If it did and you had a key for it then you wouldn't need to use the catch to close the cupboard, right? It should be possible to replace the spring in the same way as for the latch.
Step 3: Make a New Spring
Making a proper, correctly tensioned spring is not an easy job. Spring steel of the requisite strength is very brittle and will snap if you try to bend it in a tight radius unless you heat it, and doing so will mean that the springiness is lost and will have to be reinstated with further heat treatment and quenching. Fortunately, the steel from an old retractable measuring rule is thin enough to bend without the need for heating, and although it doesn't make a very strong spring, two pieces used together will compensate.
There is still a danger, even with the relatively weak spring steel in a cheap retractable rule, that it will break. So wear your safety specs from the moment you start work on the spring until the case is safely closed and the latch is ready to refit on the door. The cut edges of the steel are also very sharp so take care when handling it.
Proceed as follows:
- Using the tinsnips, cut a generous length from the old steel rule. Use the old spring as a guide, or your paperclip if you couldn't find the old spring.
- Cut down the length of it to make two strips that are each a little narrower than the height of the pin that the spring wraps around.
- Gently bend the central portion of one strip into as much of a circle as possible, using the round-nosed pliers. If you don't have any then find a nail that is the same diameter as the spring pin and form the spring steel around it. Work slowly and gradually.
- Then bend the steel outwards, away from the circle, to form a keyhole shape. Keep trying it on the pin. You need it to be a loose fit, but the circular shape must be sufficiently complete for it to be held captive on the pin. The only way it should come off is if you lift it off.
- Do the same with the second strip. Then put one inside the other and make any adjustments that are needed for a good fit on the pin.
- Tweak the angle of the legs until the latch mechanism works properly - you may need someone to help you hold everything in place. Remember that if the latch is operated by a lever rather than a knob, the spring needs to be strong enough to hold the lever away from the vertical when the door is closed. (Have a look at the photo of the outside of the cupboard - the first in Step 1 - if this doesn't make sense.)
- Now check the length of each leg and trim them if necessary. If they are too long then they will prevent the cover from going back in place.
Step 4: Reassemble and Test
A squirt of WD40 or similar dry lubricant wouldn't do any harm before you put the catch back together.
Getting the cover back onto the backplate with the latch spring in the right position is fiddly, especially if there is a lock spring to worry about as well, but it is possible. You might need to use something like a blunt knife blade to push the outer leg of the new spring away from the side of the case while you ease the lugs into their holes and squeeze the thing back together. A second pair of hands is recommended.
The catch will come apart more easily in future, as the lugs have been loosened. But I wouldn't worry about it because once it is screwed into position on the back of the door, or in a mortice, it isn't going to fall apart.
Pop the spindle through the square hole and check that the latch works before you go any further. This is particularly important if the latch is operated by a lever - try it on the spindle and check that the spring is strong enough to hold it in the closed position. Don't forget to test the lock still works too, if there is one.
Assuming everything is OK, fit the catch back on the door, then the spindle and handle.
This repair may not last for ever, but once you've done it once it's easy to make a new spring should you need one in the future.