Mechanical combination gate lock for the front door

Published 06/04/2021 · Comments: · Reading time: 7 min · Views: Post Views: 3,693

Previously, combination locks could only be found on doors at entrances or in industrial buildings. Now they have become common in the private sector, which has increased attention to them. Today you will learn how to choose a good mechanical combination lock and install it.

Where and why do you need a combination lock?

A lock with a code can be hung anywhere: on the gate, on the door to the entrance or to the apartment.

It will be especially useful on the gate of a private house or cottage.

There are several reasons:

1. You won't need a key to open the door.
2. No need to worry about vandals knocking it down.
3. It is more difficult to break into than regular keyed locks in the same price range.

The most convenient mechanical types of door locks. They are autonomous and do not depend on electricity or charge.

External code panel: what to pay attention to?

When choosing the manufacturer of the strength and its shape, it is necessary to concentrate attention on the external control panel of the locking device. Its installation is carried out externally by the door or gate.

The main types of external panels are:

• Push-button remote control. It has gained widespread popularity in municipal settings, and is actually used in entrances, government. organizations, office organizations. They are easy to use, reliable and do not require any additional maintenance.
• Optical remote control. More often they are used in country houses. They have the probability of synchronizing with the guard concept.

Advantages and disadvantages

The advantages of mechanical combination locks include:

1. High reliability. As a rule, their locking part is much better than other types of locks. For example, the thickness of the tongue can be more than a centimeter. It is almost impossible to knock down a door with such a lock.
2. No key needed. In many cases, this is convenient, because... You won't be able to lose it.
3. Stealth. The entire mechanical part is hidden behind the door, so intruders will not be able to open the door. This qualitatively distinguishes a code key from an ordinary one, which can be faked.

Flaws:

1. Still, the code can be opened. On cheap mechanical locks, the buttons are made of ordinary steel, which corrodes. At the same time, the combination keys remain clean, because oxides do not accumulate on them. You can also spy on the code or, which is unlikely, guess it.
2. Cheap mechanical locks can jam. Over time, they become coated with oxide and become much more difficult to open. They need to be lubricated and cleaned regularly.
3. The code is set by the manufacturer. Unfortunately, there is no way to change it. Specific buttons are responsible for specific plates. Considering that many budget manufacturers use standard codes that can be found on the Internet, they protect the home very mediocrely.

Don't miss: How to weld hinges to wickets and gates - basic welding rules

Let's get back to math

The box idea I described above inspired Diffie and Hellman to look for a way to convey a message. Eventually they ended up using one-way functions.

What is a one-way function? For example, there is a doubling function, i.e. double(4)=8, it is two-way, because from result 8 it is easy to obtain the initial value 4. A one-way function is a function after applying which it is almost impossible to obtain the initial value. For example, mixing yellow and blue paint is an example of a one-way function. It’s easy to mix them, but it’s impossible to get the original components back. One such function in mathematics is modulo calculation.

Hellman proposed the function Yx (mod P) as the basis for the algorithm. The inverse transformation for such a function is very difficult, and we can say that, in essence, it consists of a complete enumeration of the original values.

For example, you were told that 5 x (mod 7) = 2, try finding x, huh? Found it? Now imagine that numbers on the order of 10300 are taken as Y and P.

By the way, to increase stability, the number P must be a prime number, and Y must be a primitive root modulo P. But since we are still trying to understand the theory, I don’t see the point in bothering with this.

Principle of operation

All action rests solely on mechanics:

1. When the bolt is closed, the return spring is charged, and the trigger head is on the bar.
2. When you enter a secret code, the buttons move specific plates that release the head.

All combination locks on the front door have a similar design. The only difference is the quality of the components. More expensive locks use stainless steel parts with chrome alloying.

How to choose

If you want to buy a mechanical combination lock for a gate, pay attention to the following factors.

Reliability class

There are 4 safety classes in total, where 1 is the lowest. For mechanical locks, the norm is 3rd degree, which is enough to deter “average” intruders.

However, as a gate lock, this is a secondary requirement. This is due to the fact that you can jump over the gate.

If you want maximum security, choose electronic combination locks that have a more sophisticated locking system.

Price

Mechanical locks are inexpensive in principle, so it’s worth buying the most expensive one. They are guaranteed to have stainless steel parts. It will not jam, and oxides will not form on the buttons.

Code

Because in cheap models it is set by the manufacturer and always consists of three keys, choose the most confusing one. It is advisable that the buttons be located at a far distance from each other to complicate the selection in case of hacking.

It is advisable to buy locks with the ability to change the code.

Manufacturers and their prices

The manufacturer is one of the determining criteria when purchasing. Both the reliability class and the price depend on it. The following brands are most commonly found on sale.

Mettam

The most common castle in the Russian Federation. Often it is placed on entrance doors, because... they can easily withstand mechanical hacking.

The advantages include:

1. Good quality parts. The manufacturer uses high-carbon steel, so it can easily withstand heat and mechanical breakage. The main drawback is corrosion.
2. Low price. On average, their locks cost from 1,100 to 1,650 rubles. In addition, you can buy them at any construction store.
3. Certification included.

Rigel

Manufacturer of simple, budget locks. Protection class 1-2, so they are bought for summer cottages. The quality is quite mediocre, but it can save you from mechanical hacking.

The main advantage is the price. On average, a castle costs about 650-700 rubles. Be careful, because... The manufacturer's code set is not diverse, so they can be hacked. In addition, the buttons are made of ordinary steel and are subject to corrosion.

Don't miss: How to weld hinges to wickets and gates - basic welding rules

Vinci Locinox

One of the few manufacturers that focuses on design. There are a bunch of colors in the catalog, but the shape is typical.

The degree of protection is 3, which allows them to be placed on the gate of a residential building. They are rarely found on sale and only in large chain stores.

Made in Italy, so the price is above average - 1500-2500 rubles, depending on the model. But all the components are made of good stainless steel.

Atis

One of the best manufacturers of mechanical and electromechanical locks. Maximum protection class. There are rulers with cool designs, but the price is appropriate - from 7,000 rubles.

Apecs

It is profiled on simple padlocks with a code. The degree of protection is low, so they are often placed on country gates.

The code is four-digit, so it’s difficult to hack them “programmatically”, but you can beat them off. The corresponding price is 350 rubles.

Requirements

In total, there are several requirements for mechanical locks with a code:

1. Resistant to opening. Those. The code should not be easy to select. As a rule, locks have 10 keys and a four-digit code, which is about 10,000 combinations! Theoretically, you can pick them up, but it will take a long time. Considering that the mechanics do not involve any software content, it will not be possible to open the lock using third-party methods.
2. Anti-vandalism. They should not be afraid of flooding, impacts and other things. A good metal lock is not afraid of this.
3. Burglary resistance. Even domestic locks, like “METTEM”, are not afraid of breaking with a crowbar or a nail puller.

Design and color are a secondary issue, because... they do not affect operation.

Device

Devices of this type are presented in two modifications: magnetic and push-button. In the first case, the door is opened using a magnetic card or key with a combination of symbols written on it, which plays the role of a code. The push-button model opens by typing a code. In addition, such a lock can be controlled remotely.

It is often used where there is an automated access system, as well as in intercoms. It can also be installed on interior doors.

A magnetic lock is recognized as the safest, as it is the most resistant to burglary. The operating mechanism in this case is based on the influence of an electromagnetic pulse that arrives at the control panel. But it was not without its drawbacks. When for some reason there is no electricity, the lock is turned off or blocked. To avoid this, you must ensure that the lock has constant power supply, or equip it with a manual opening mechanism.

Door installation

Installing a combination lock is easy, especially if you have all the tools at hand. To work you will need:

• Set of drills;
• Drill;
• Screwdriver;
• Pliers;
• Roulette;
• Crosshead screwdriver;
• Wire cutters;
• Pencil.

An example of a Selock Code 20B lock will be shown. This is a universal model with 3 degrees of protection. Can be installed both on apartment doors and on gates.

When everything is prepared, you can proceed to installation:

• First, inspect the package. It must have a complete set: the mortise part, covers, code battery, locking mechanism and fasteners.

Don't miss: How to weld hinges to wickets and gates - basic welding rules

• Installation is carried out on a metal sheet door.

• You will need to make a through hole for mounting. You can do it with a drill at a convenient height.

• A locking part is inserted at the end. It must go strictly perpendicular, otherwise the lock may jam noticeably. The locking part is fixed with supplied screws.

• Now you need to drill the counter mounting hole.

• Then the code battery is inserted. Already at this stage you can check the operation of the lock. Try to dial the combination - the locking tab should open.

• Now cut the pivot bar to size. It should cling to the tongue, but not interfere with its movement when opening.

• Embed the mating part. It is installed at the level of the locking tongue.

• All that remains is to install the internal handle.

This completes the installation. You can check the constipation for squeaks and crunches, and lubricate as required.

Replacing the code on the lock

Some locks allow you to change the password mechanically. The code change will be shown using the example of “METTEM”:

• First you need to unscrew the back cover.

• Here is a block of plates responsible for entering a password.

• Look at the plates at an angle. You will notice that there is a slight bevel on the edge. He is responsible for the password. Those plates where the bevel is located outward are not used. The key ones are those where the bevel faces inward.

• All you need to do is turn over the required plates. According to the manufacturer, to achieve the required level of security, use 3 digits. If there are more, it will be easier to guess.

Step by step guide

When installing a lock, all calculations must be accurate, and the necessary tools must be available. You will need: tape measure, wire cutters, drill, drills, pencil, pliers, screwdriver bits.

1. Mark the measurements with a pencil where the device will be installed.
2. Drill holes according to the dimensions of the lock with a drill.
3. Attach it to the door.
4. Insert the bolt into the strike plate.
5. Connect the cable to the device.
6. Use a screwdriver to attach the handle to the lock itself.
7. Replace the cover.
8. Enter a code.
9. Check functionality.

Do not drill holes too close to the edge as this may cause cracks and splits. A gap must be left between the crossbar and the end part. The work must be carried out as accurately and accurately as possible.

If you forget the code, you can remove the cover from inside and reset the code. Take out the plates and turn them over in the opposite direction, this will be more convenient and reliable; you should program the lock according to a scheme convenient for you.

Tips for use

Mechanical locks are undemanding to use, but you still need to follow a few rules:

1. Lubrication. The locks must be lubricated periodically to prevent them from rusting or jamming. A good machine oil that can easily withstand low temperatures is best. There is no need to feel sorry for it - all components should “float” in the liquid.
2. Protection from cold. During the winter, the water particles between the buttons freeze, which causes the buttons to “stick.” Penetrating lubricant WD-40 will help here. Periodically fill the button block with it.
3. Code change. Some locks, like “METTEM”, allow you, albeit with difficulty, to change codes. This will provide the necessary level of security.
4. Put on the visor. It is recommended to install a plastic canopy over the lock to prevent water from getting inside. If the locking parts and buttons are made of ordinary steel, they will begin to rust and jam.