All About Key Cutting and Why Duplicate Keys Sometimes Do Not Work

At some point in time, you may need to cut additional keys to your home – typically to grant access to your property to other trusted individuals or to replace lost or damaged keys.

Every town and city is likely to have multiple choices of key cutting options from national franchises to market traders.  But what is the best options to choose, what do you need to consider and why is it that key copies sometimes do not work?

This article, written by Lock Guy (a professional locksmith based in Essex), discusses all about key cutting for typical household locks and why duplicate keys sometimes do not work.

What is Key Cutting?

It is the process of shaping a key so that it corresponds to the precise configuration of the internal mechanisms of a lock allowing the key to operate that lock.

A Quick History of Key Cutting

Basic locks have been around for thousands of years and the first keys were hand carved from wood. Metalworking meant the development of keys made of bronze and iron (600-1500) using hand tools like files and chisels.

The development of pin/lever operated locks in the 19th Century required a more precision key and this lead to various jigs and guides being developed to ensure accurate cuts. This in turn lead to the first electric key cutting machines being introduced which were commonplace in the mid 20th Century. By the late 20th century, computer controlled (CNC) machines were common and laser cutting was introduced.

Read more in my article about the history of locks

The Key Cutting Process

  1. Key blank selection

The process starts by selecting a key blank. There are thousands of key blank variations with different types with different profiles, lengths, thicknesses, etc…

  1. Key duplication

The original key is placed on one side of a machine that acts as a template for the new key. The key blank is placed on the other side. The guide (for the original) and the cutter (for the blank) are set to identical positions. As the guide follows the contours of the original key, it cuts the blank. 

  1. Finishing, testing and adjustment

Some finishing is normally needed to smooth out the cut edge and remove any burrs. This can be done with a wire brush and/or gentle file. The key is then checked against the original (or even in the lock if that is available) and can be adjusted by hand if needed.

why duplicate keys sometimes do not work

Why Do Key Copies Sometimes Not Work

I’ve been to many jobs where people have had duplicate keys cut and am often asked why duplicate keys sometimes do not work. It is not uncommon for people to experience difficulties with duplicates of a key. 

Reasons:

  • Tolerance Drift: It is not possible to make a perfect copy of a key using a standard key cutting machine. There will always be very slight deviations.  Every time a copy is made from a copy, these deviations can become larger which could cause an issue in the lock.
  • Poor expertise/workmanship: There are no official qualifications/standards that key cutting operatives need to follow. Whilst the machines do most of the work, there is still a skill to it and quality levels do vary greatly in practice.
  • Accuracy / Calibration: If the key cutting machine is not maintained or set-up properly, then it can produce inaccurate results. Whether the machine is old or new is not really relevant – but if the machine is out of calibration – it will not cut a good key.
  • Wrong key Blank Selection: Some key blanks look very similar to the naked eye, but are not the same. Choosing the incorrect blank could lead to operating issues with the key.
  • Lock issue: It could be that the lock is partially at fault. Sometimes by lubricating the lock it can improve the performance of keys. Read more in my article on maintaining locks.
Lock Guy key board

Where to Choose to Get Your Keys Cut?

National Chain  

Whilst these companies may have a good, well-known brand name – they tend to have a poor reputation based on the available online reviews and based on anecdotal evidence.

Independent Retail Outlet 

This can be a bit ‘hit & miss’.  Look for recommendations on local Facebook groups for the ones which can be relied upon.

Market trader

Probably best to be avoided as these types of operations may not have a wide variety of blanks and may not have the best equipment

Mobile locksmith

This is probably the most expensive option as a professional locksmith will charge a lot to come to your property.  The advantage is that they can test there and then if the new key works in the actual lock.

Automatic Vending Machines

These work by digitally scanning the key.  Therefore they are quite accurate, but lack the ability to do the ‘finishing’ process as well as a capable key cutter would be able to do.

In conclusion – Select a reputable local independent retailer.

High Security Key Cutting

Many lock manufacturers offer high security options. One of the features of such high security locks is that the key cannot be copied by a third party : they would be unable to just get a key cut without your knowledge/approval. Normally these types of keys have to be registered to the owner and only that person (by email authorisation) is able to approve copies to be made. To ensure this security control, the key normally has a unique profile and the supply of the blanks is strictly controlled to a small number of approved key cutting providers.

Additionally, standard key cutting machines are unable to cut these keys as they can only be done on particular machines.

For example of a good security key offering: https://vimeo.com/694070923?fl=pl&fe=sh

It is best to ask the manufacturer how to get copies of high security keys.

Please note that the cost of getting high security keys cut will be more expensive than a standard key.

Can You Get a Key Made for a Lock With No Key Present?

Yes, this is possible – but it is not always viable.  It largely depends on the type of lock.

Key impressioning is a process whereby a locksmith can ‘read’ the profiles of the lock and make/cut a key to correspond to it.

However, this process can take time and it is often more cost effective to just replace the lock.

Some locks have a code stamped on them and that can be quoted to the manufacturer who may be able to supply a replacement.

Advice:

Wherever possible, always get keys cut from the original manufacturer key.

Do not immediately rely on the newly copied duplicate key. Do not assume that it will immediately work. Test it first before giving it to someone or start using it as your main key.

Costs can vary, but you should not need to spend a lot. The blanks for standard keys are very cheap for the key cutting provider to buy!

For further information on Key Cutting in Witham, Maldon or across Essex, contact Lock Guy

Got a question about a lock issue you may have? Why not have a look at the FAQ page or one of the helpful advice videos on the Media page