Removing broken mortice lock

Ha! Might just have answered my own question on the Googles.

Try

SF do 1mm cutting discs

What sort of door/lock is it? Is is also a latch, with handles and plates either side? If so, can you see any of the guts if you remove the handles and plates?

I recently had exactly these symptoms with a Eurolock-based latch/lock mechanism in an aluminium door between my house and conservatory. A bit had broken inside the lock which meant that turning the key no longer lifted the interlocks out of the way of the bolt, with the result that the bolt couldn't move more than a mm or so. By removing the handles and plates, I was able to poke around with a screwdriver and lift the offending interlock manually - enabling the key to unlock the bolt.

On Wed, 14 Oct 2009 22:01:29 +0100, "Dave Baker" had this to say:

If you _could_ get a 1/25" cutting disk for an angle grinder it would be so fragile that you'd have to use some sort of a jig to guide it without any twisting.

WD-40 would seem to be the answer to all your prayers, if you can believe a few posters in here....

It's not a Yale lock, is it (lubricated with the above as recommended by Yale)?

It wouldn't have jammed had it been lubricated according to the manufacturers instructions e.g. with WD40.

"Stainless steel cutting disks" (Screwfix, and Aldi, et al)

Extra thin, bit brittle and the wear rate is high, but they're great for mortice bolts.

First thing I tried but all that's behind the plates is a little hole in the wood for the key to go through and then the keyhole in the lock itself. Nothing further to dismantle unfortunately. A thin grinding disk seems to be the way to go now I know they exist. Should be a piece of cake once I get some to fit my grinder.

Got around 50 in the back of my van for a 5" AG. Cut like lasers they do

The locksmith's method I've seen is to drill through the door, into the lock body, at the right point (say a 6mm hole) to lift the tumblers with a wire or thin screwdriver, and then to use a timber plug or dowel to patch the hole.

You would need to dismantle an identical lock to figure out where to drill.

... and the thinnest are 0.8 mm.

You may want to scrounge around for a very worn disc as a shim and support -- the thin discs come with a bit cardboard, but an old disc is better.

Thomas Prufer

The handle plates are pretty big, 2" wide or so and I'm now thinking I could chisel out the wood under one side to about 1" wide behind where the mortice goes, get in there with my cylinder head porting gear and carbide burrs and rip the lock open and just destroy everything behind the mortice until the lock's an empty shell. Once the plate's back on it'll all be hidden. Might take a while but given I have this gear and not the cutting discs it sounds like a plan.