More mortice lock questions

It's probably a standard size. What brand is it?

It will be a "standard" size - but there are *lots* of standards - so you need to measure all the dimensions - length, width, offsets, etc. and find another one the same.

Does yours look anything like this?

If I could get it out I could maybe tell you but at present "unknown origin" is my best guess.

has only 3 prongs on it though and I've just had a measure and it's exactly

OK, best to take it to the shop when you do finally get it out and compare directly with potential replacements. If it is a well known brand, you should consider starting with that brand.

If you want to upgrade to a higher spec., e.g. Chubb BS3621 Insurance Approved, then you should be aware that Chubb do the 3K74 and the 3U74, which are notionally identical apart from the fact that the 3U74 case is sized to replace "standard" Union/Yale locks and copies thereof.

Union 3-lever lock dimensions on this page. (Note that 3 lever locks are fairly easy to pick)

or shorter:-

I'm fortunate in having a large speciality lock shop quite near. When I replace locks I always take the old one there & so far they have always been able to supply an exact match.

NT

IME Often the new lock is a standard-ish size but the box staple (?) (the bit the bolt locks into) isn't.

Derek

That's a good start, but there are other dimensions which might vary - like the vertical distance between keyhole and latch. They're all shown in the link posted by 'Geo'.

In article , Roger Mills writes

I think the strike side will almost certainly need opening up, the deadbolt width increased a bit with the 2004 revision of BS3621 so things had to move to accommodate it. At least the strike side is the easier one to modify. The strike box will be deeper to take the longer throw too.