Impressioning a key for a secure box

The art of impressioning a key to a lock is difficult to master but once learned will definitely pay dividends writes Steve Coombes

[dropcap]I[/dropcap] was recently asked if I could open a secure box and make a working key. The best way to tackle something like this, in my opinion, is to impression a key to the lock.

Unfortunately, this is a little used skill among modern day locksmiths but one I pride myself on. This art is difficult to master but once learned pays dividends.

Due to the warding in this lock it would have been difficult to open by any other means. The customers also wanted a working key and obviously no damage to the box itself. Curiously, the heavy warding actually makes things a little easier as there are no lever heights to work out.

The treasure box

The first thing to do is find a key to fit. The keyway is very large in this box and I knew that finding a 2G pipe key would be very difficult, if possible at all.

After phoning all my usual suppliers, I bought a few of the largest church keys available with the hope I could adapt one of them to fit the keyway.

The next thing to do is grind the bit down. Being a very large key, the bit was oversize by 15mm in length and about the same in width. I find the best way to do this is either on a bench grinder, which I prefer or to cut it down with a hacksaw. I also had to grind some off the thickness as it was too thick as well.

Picture 2 – carefully grinding down the key whilst not forgetting the principles of health & safety.

When doing this, be sure to take off just enough so as the key fits the keyway. You can always take more off later but you can’t put a bit back on if cut it down too short.

The next job is to drill out the pipe to the correct gauge. This is best done in a lathe or drill press. I had to rely on doing it by eye and drill, as I have neither. Using a 7mm drill, being careful to keep the drill upright/in plane, drill down the pipe just longer than the pin itself, keeping it cool as you go. Too hot or too far will weaken the key, while it could also snatch and destroy the blank.

Picture 3, careful drilling.

Picture 4: I also had to reduce the outer gauge before it would fit the keyway.

Now the fun of impressioning

Due to the keyway being large, it actually made the process a little easier.

Using a probe and eyepiece, I could see that there was a centre ward from the tip of the bit, right down to the shaft of the key, this is the first cut to be made.

Picture 5 shows me using the keysaw to cut the central ward

Picture 6 shows me still going 20 minutes later

Some of the pics look blurred – they are not. This is just the swarf from the job.

The best plan for any impressioning job is to keep the surface clean. I do this before I take each reading as it takes away any soot or marks left from previous readings. All I do is rub away the ‘soot’ with a little steel wool before carrying on with the task.

To get the marks, or readings, after each clean, I ‘smoke’ the bit by holding it over a candle. This is basically to get the soot on the face of the bit to make the markings stand out more. I use little tea-lights rather than a lighter. The candle produces a far better soot layer, which is also slightly waxy. I find this gives a more even covering and it really blackens the bit making it easier to see any marks.

Picture 8: ‘smokin…’

While difficult to see on Picture 9 (indicated by the screwdriver tip) you should just be able to make out the first witness mark.

Picture 9: Look closely

Cut along the mark, being sure to stop where it finishes. Going any further might mean cutting too far. {This is going from the centre already cut ward out towards the blade – Ed.}

Once you have cut down to where the mark finishes, repeat the process – clean, soot, rub on the wards.

As you can see, it turned out I hadn’t quite cut down far enough. The cut was taken down to this next mark before proceeding.

Picture 10 – a clear witness mark.

Keep going with this process, remembering to clean and re-smoke the bit each time. The last thing you want is to put a cut where one isn’t needed as this will just weaken the key, ruin the blank and you have to start over. If you find there aren’t any marks on the face of the bit, look at the inside of the cuts themselves, it may be that a cut is rubbing on the side of a warding. I use a small needle file to get into these.

Picture 11 – marking up nicely now but steady does it, a lot to lose if this goes wrong.

This is the last cut to be done on the key. As you can see by the position of the last mark, care is needed. Any deeper with the cut on the right and the tip would have fallen off.

Picture 12 – and the cuts are finished.{Nice shoes – Ed}

 Cleaning up

One of the most important jobs is the clean up. Now the cuts are finished, clean the shaft and bit using some wet and dry and some steel wool. Take off any burrs using the needle file inside the cuts.

Taking a little time and effort to get the key looking presentable is a job worth doing. It shows your customer you have taken care and just makes it look a finished job.

All of the cuts shown and described here, were done using a keysaw with a 1.5mm blade in it. I went through about five or six blades to do this key – and a file.

[box type=”info”]Meet the writer

Steve Coombes Age: 36
Company name: Prospect Locks, Kent and East Sussex
Ardent supporter and member of ICL
Daily work – Domestic and commercial locksmith (specialising in NDE).[/box]

Steve started out in working life as a humble carpenter and joiner. Got into fitting and servicing locks and door closers for a few maintenance companies and progressed from there.

Says Steve: “I Started Prospect Locks in 2005. Since then, I have concentrated a lot of time and effort into the NDE side of the trade, alongside the rest of my work.

[quote]I used to do warrants on a weekly basis but since getting contracts for local council and Kent Police, I now concentrate on these and private clients/contract work. I feel that keeping yourself informed on product development and having the ability to adapt to the changing climate is a must in this trade to be able to give your customers the best options available.[/quote]

“My daily work could range from gaining entry for some little old lady to keying and fitting a master suite for a block of offices. I like the variety of work.”


  1. Nigel on 23/01/2012 at 1:50 pm

    Paul, it is very difficult to charge what a job like this actually should cost. Unless the box has significant value, most people will destroy the box to get the contents when told the job will cost over £50!

    One solution is to barter for the box, while they get the contents, and you cover the job for a small or no fee. Not a very good solution, though…

    It’s not realistic in a lot of cases to meet the customer expectations. I once had a job a bit like this, for a little old lady. She had been told she could get a new key for £5. I told her I would charge more than £5 to cut a copy of the key that would have worked in the floor standing, 4′ by 5′ high safe she presented to me! And guess what? She didn’t even have a key!!

  2. Paul-Fletcher on 04/01/2012 at 10:03 am

    Nice job Steve but how much did you charge for the work? I often get asked to do these kind of jobs but feel that i massively undercharge when the time taken is costed against the price that can be charged. For example an old box that someone finds in the loft and expect to pay a tenner for a key to fit?

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