On Thu, 31 May 2018 14:41:28 +0100, GB
wrote:

On 31/05/2018 14:23, Harry Bloomfield wrote:
GB wrote on 31/05/2018 :
We have a night latch - one of these:
https://www.ironmongerydirect.co.uk/...-chrome-850075


What is the best way (ie easiest, not necessarily cheapest) to convert
this to combination lock?

The easiest way, is to use an electric one. You would need to replace
the part which fixes onto the door frame (the latch ?), with a solenoid
operated version, then add a suitable keypad and logic somewhere near
the door.

I was hoping just to replace the cylinder with a combination version,
but I suspect that that does not exist. Due to location, it needs to be
mechanical.

You could fit a mechanical code lock such as
https://www.ironmongerydirect.co.uk/...-chrome-233214
but they are significantly less secure than the lock you are replacing
in that the 4 digit code can be entered in any order - so 1234 or 2431
etc will open the lock. Over time the 4 valid numbers tend to be easy
to spot by deposits of dirt etc on the number pads. (All mechanical
locks have this problem).