Rekey.IT – Granny Flat locks keyed alike

I am not a locksmith, but I am an engineer. Often engineers are required to fix things that are not always broken – anyway, I digress.

On Wednesday, a locksmith came to install a Lockwood 3582SC narrow mortice lock into our new aluminium gate. The gatepost is a standard 50x50mm aluminium extrusion, and as it was an outwards opening gate, the choice of locks was very limited. The gate was also part of a new fence that was installed at the front of our brand new granny flat, and this gate was the only exit from the granny flat onto the street.

If we were not concerned about safety, we could have used any of the inexpensive gate locks, where the pin would have to be on the fixed post, and the latch is on the gate. We didn’t like this idea as the thought of a pin sticking out at any height would be an accident waiting to happen – i.e. child running past knocking into the pin, or if it was higher, an adult poking his eye out.

So we went with a much more expensive lock that fits inside the gate itself, with keyed cylinders inside and outside, and a blocker plate to stop people from trying to jimmy the lock – not that it could happen, but why allow people to think that it could be done.

Yesterday, we had been thinking about the locks on the granny flat. We have a key for the gate, then a key for the security screen door, then a key for the front sliding door then another key for the back door. This makes it four keys excluding the window keys. How convenient would it be just to have one key. Also thinking about what would happen in an emergency – you want to exit quickly, and fumbling about to find the right key can be problematic especially when panic starts to set in.

We decided to make changes, so that no key was necessary to exit the granny flat. At the same time, we should get the locks rekeyed so that only one key is needed to get in and to lock up when leaving. The back door deadbolt was replaced to be a single cylinder instead of the current double cylinder.

Did you know that getting a lock cylinder rekeyed costs around $38.50 each, so a lock with two cylinders would cost double that. In actual fact, most locksmiths will sell you a lock, and key it to your existing key free of charge, so instead of rekeying, you could buy a new lock for your key – especially since I wanted to change things around.

Anyway, I was going to do the rekeying – the locksmiths would do that, however for the gate, I was just going to replace the inside cylinder with a turnsnib – a knob that takes the place of the key turning. Ok, it isn’t as secure as a key, but in an emergency, getting out quickly is safer than being secure.

I ordered the appropriate locks and cylinders for what I wanted to change and got the turnsnib to put onto the gate lock. It is a simple matter of having the gate open, then removing two screws to get the cover plate off, pull out the retaining pin for the inside cylinder, remove it and insert the turnsnib, then put the retaining pin back on and install the cover plate again.

Sounds simple when you write it like that. In practice it wasn’t. I could remove the cover plate screws but couldn’t get the cover plate off until I loosened the two screws holding the lock in place. Then the retaining pin would come out until I loosened the handle furniture. Ok, got the pin out eventually, then removed the cylinder and put in the turnsnib cylinder – almost done.

Then I couldn’t get the retaining pin inserted – I could get it partly but I didn’t want to force it. Better get some advice, since I had to take the new deadbolt back anyway, because my key wouldn’t turn it. I put everything back on, but then couldn’t get the handle furniture back on.

The advice from the locksmith was that I may need to hammer the retaining pin into place, since it can be tight – ok. After much playing around with the lock, I eventually had to remove everything from the gate. Remove the blocker plate, remove both handles, remove both cylinders, then remove the lock from the gate. Did I mention that the locksmith spent an hour and a half installing this in the first place, and charged me $200+ to do it and here I had the whole thing taken out!

With the lock out, I put both cylinders in, the keyed cylinder was easy, but the retaining pin for the turnsnib would go in with difficulty except it would jam when it had to go in another 3-4mm – this is the part where the hammer is needed. I put the lock back in, then tried putting the cylinders in – this is where I found that the cutouts for the cylinders were the problem – the cutouts were out of alignment so the turnsnib cylinder would jam up against the side of the gate.



Out comes the lock, then in with a metal file and filed it until I could have the cylinders in without jamming. Next to check why the handles would not go in properly – again, the holes where the screws go to secure the handles were out of alignment, this time by a few mm. Out with the lock again, then in with a round file to open up the holes. I had to do this to both sides, until finally, the lock and handles could go in without difficulty – fantastic.


The photo shows the lock in place without the cover plate, and both handles installed. Install the keyed cylinder on the right of the lock – done. Install the turnsnib to the left of the lock, with a few taps of the hammer, the retaining pin went in with difficulty. Then put the cover plate on – it wouldn’t go on flush, but a bit of a tap with the hammer, then tighten the screw – do it again, tighten a little more. The cover plate now is ok to use, so job finally done.

That is, after two hours of effort – knowing what I know now, I might even have been able to install the lock from scratch in that time – if I had an angle grinder to cut the slot for the lock, and the right size hole saws. Actually, I still had to install the blocker plate, but that was easy – only two long screws.

P.S. If I had been able to get the gate post before the gate was assembled, I could have put it on my milling machine and cut all the slots and holes properly for the lock before the gate was assembled – maybe on the next gate.

Regarding the deadbolt, after they fixed up the keying, I installed that easily. The euro cylinder for the security screen door – I had to go to Bunnings to get a M5 countersunk screw, since the original euro cylinder had a 3/16″ screw which doesn’t fit the new cylinder. Did you know that Bunnings only has stainless steel M5 countersunk screws, but plenty of imperial sizes in plain zinc coated.

Oh, the sliding front door lock – is still coming in, maybe in a week – supposedly a standard fitting, easy to do – we’ll see.