In the case of the switch, the core conclusion is a 20-40-minute switch from the common security door to the master, half an hour to one hour (newer) or 5-15 minutes (advanced), depending on the type of lock core, the condition of the door and your ability to handle it. If you are a renter, you should change the lock core on the day of residence and return the old lock core when you check out at the lowest cost; if you are an owner, you should either upgrade the c or the super b lock core directly and find a licensed master or do it yourself, but don't try to use the a-class lock core cheaply。
01 time cost: 20 minutes to 5 hours, key view
Based on the measured data of professional masters and senior diy players, the time taken to change the lock core can range from dozens of seconds to five hours, mainly influenced by three variables: the type of lock core, the operator, the conditions on the ground。
The lock core type determines the base time. The most common common household security door (a/b/c-class mechanical lock cores) usually takes between 20 and 40 minutes for professional masters to enter the house. If the lock structure is simple and the master is experienced, it can be done in less than 20 minutes - this already includes the whole process of breaking old locks, measuring sizes, adding new locks, debugging tests. However, if a c-class high-security core, electromagnetic or intelligent lock is more complex, the installation is highly accurate and may be extended to one to five hours. Some of the smart locks also require the resetting of passwords, the matching of mobile phones, or access to smart home systems, which often take more time than mechanical installation. Car lock cores are more specific: normal mechanical car lock cores are replaced for approximately 2-3 hours, and a vehicle model with a remote key or anti-piracy chip requires a key code matching, which usually takes about 4 hours。
You can do it yourself. Weibo grand v's houses shared his experience: he spent more than a decade on the property, working to the extent that the lock cores were replaced in half a minute — 5-10 seconds for unlock cores and 10-20 seconds for lock cores. He also stressed, however, that this was the result of long periods of exercise, not of ordinary people. For beginners, the first change of lock cores requires a control of the curriculum, the removal of old locks, measurement of size (total, centre distance, etc.), installation of new locks and testing, which usually takes 30 minutes to one hour. Experience reduces it to 5-15 minutes. So if you're looking for efficiency, you're looking for a teacher; you want to save money and you're willing to spend time studying, you can do it yourself。
The field condition is the largest " hidden variable " . The deformation of the door frame, the erosion of the lockhole or damp would seriously hamper operations, and additional 5-15 minutes would be required for lubrication or cleaning. When the old iron door was rusted, the master had to be treated repeatedly with lubricant. In addition, if you buy the wrong lock core size (total size, centre distance mismatch), you can only repurchase or adjust the door, then the time is simply doubled. The most prudent approach is to remove the old lock core and take it to a building or lock town with the same or measure the size of the re-purchase。
To facilitate comparison, look directly at the following time frame:
The scenario is estimated to take time
Get master to change the alarm lock
20-40 minutes
Get master to change security/smart lock core
1-5 hours
Change car lock core with master
About four hours
Do it yourself
30 minutes - 1 hour
Do it yourself
5-15 minutes
02 cost comparison: save half of your own money, but with a premise
The cost of the lock-up service consists mainly of two components: the cost of lock-tip material plus the cost of door-to-door service (including installation)。
Cost of self-replacement: a c or ultra-b lock core, usually at a price of between $100 and $300 for the purchase of materials or networks. If you do it yourself, there's no extra time. In the experience-sharing with twitter, the "doctors suite" highlighted the fact that, in exchange for a lockman, they recommend a c-class lock core, but the price is usually twice or twice as expensive as if you were buying the exact same lock core. In other words, by buying the lock core itself, you can save at least $100-200。
Cost of switching to a teacher: the formal lock-opening company will be able to change the lock-up core and charge a service fee (usually between $50 and $150), in addition to the cost of lock-locking the core material. If the master had his own lock core, it would have been included in the general offer. Taken together, the total cost of a common door-to-lock switch-to-man is approximately $150-400, which is considerably higher than the cost of pure materials。
But there's a threshold: you have to measure the size of the lock core (total length, centre distance, panel type), and the wrong buy leads to failure to install. And if you live in an old neighborhood, the doors are badly corroded, and the removal of old lock cores may require specialized tools. In the course of a new lockout for the rental party that shares rains and tacos, the newcomers are advised to watch the video several times, prepare screwdrivers and rollers and leave the first operation for an hour. If you're weak, or if your home is a rare, non-lock core, looking for a teacher is actually a more economical option。
The renters specifically cautioned that the switch of lock cores immediately upon occupancy is necessary. As weibo grand v, chang daechuan 66, said: “many landlords who do not actually have a bottom line will enter the room without your consent.” the change of the landlord's lock core will be preserved and the check-out will be sufficient. The self-purchased lock core can be taken to the next house for continued use, at a lower cost. It also learns a skill while changing its own lock cores, without asking for help to move。
03 security: class c lock core is the reason. Don't save the money
The central purpose of the switch is to raise the level of piracy. The original lock cores of the new or second-hand rooms delivered by many developers are a or a+, and such lock cores are activated within one minute and are in vain in front of thieves. The c-c lock core (some of which is called ultra-b) has been activated for more than 10 minutes, and there is a huge gap。
Weibo's “systems of houses” explicitly suggested: “current a-class lock cores are replaced by high-level (at least above b) lock cores, and theft prevention is not a class”. The most important purpose of the change of lock cores that he has had for so many years - to prevent former owners and former tenants from keeping their keys. In particular, the renters, former tenants, may have private keys and landlords may not be reliable, and the purchase of a c-class lock core for replacement is the least costly safe investment。
One might ask: is the smart lock safer? It must be acknowledged that the smart lock is indeed easy (fingerprints, passwords, remote unlocking), but its security line is the reliability of the electronic component and the level of the emergency machine lock core. There are smart locks of less than a thousand dollars on the market, whose mechanical lock cores are often only a or b levels, and there may also be loopholes in the electronic component. So if you choose the smart lock, you have to make sure that the emergency lock core is at least level c, or you buy an electronic doorbell for the lock。
Summary: wherever you live, the lock core level must be thorium c (or superb). I'd rather spend an extra $100 on the lock core than save the money for the back door。
04 recommendations by population
Tenant parties (especially girls living alone): buy their own c-class lock cores for the day of residence, at a cost of $100-300, and retain the old lock cores to be returned. Reason: save your own money and learn your skills and prevent landlords/ex-tenants from leaving their keys. For the first time, one hour is set aside. Owners (in search of care): directly dial the official lock-in telephone number of the public security file, requesting a c-class lock-up and a promise to come to the door within 30 minutes. It costs $150-400 to save time and master experience without error. Diy lovers/players: buy their own lock cores and finish them in 10 minutes. The only short plate is a lock core size that needs to be confirmed in advance and may be used for the first time. After the exercise, however, the whole family can change its own locks and earn a manual fee for its neighbours。
05 common faq
Question: how much does it cost to change the lock core
Buying a lock core by itself: class c or super b lock cores of $100-300. (c) home to master: materials + services, usually at a total cost of $150-400. If the master had his own lock core, the offer already included profit, it would be about twice as expensive as your own lock core。
Question: does the original key work after changing the lock core
Can't. The change of lock core equals the replacement of the internal mechanical structure of the lock, the old key cannot match the new lock core and the key attached to the new lock core must be used. So when the locks are changed, the new key is kept and the spare key can remain with the company or with a friend。
Question: do you need to ask the landlord in advance to rent a new lock
It is recommended that the rental contract first be reviewed. Most contracts do not explicitly prohibit the change of locks and the change of lock cores is an operation that does not damage the structure of the house (retention of old lock cores is sufficient). In order to prevent a dispute, the landlord may be informed orally that it is generally acceptable “to change the lock core for safety and return the rent”. If the landlord strongly objects, then you should be more careful — this is probably an indication of his selfishness。
Updated: 30/07/2026
Congratulations to your sister. You've learned to switch locks today! # i don't know # fan
Pick up the house, find a bunch of lock cores. It's like a room
Renters must learn their skills. Learn how to save money. Http://www. Flickr. Com
If you live alone, especially girls, you have to change the rent
Congratulations to your sister. # i don't know # fan
