Mortise lock question

[ElbowMacaroni]

Ok, here I go again with the silly questions...

What is it that makes a mortise lock a mortise lock? I mean if you think about it, most door locks that don't move a hasp of some sort are effectively a mortise and tenon joint, and yet deadbolts aren't called mortise locks and they definitely use the principle of a mortise and tenon to hold the door shut.

Thanks for helping to clear my fog of newbirific ignorance

-EM

[Tyler J. Thomas]

The designation isn't a reflection of how the door and lock interact but how the lock is installed on the door. A mortise lock is defined as:

A locking device fit into a mortise preparation.

A mortise is basically a pocket or section of removed wood from a door, cabinet, etc. Not to be confused with a mortise cylinder, which can be a part of a mortise lock but is not that lock itself.

Hope that clarifies.

[mcm757207]

This is a mortise lock:


This is a mortise cylinder:

(Notice the threads)

Compared with this:

Which is a (cylindrical) deadbolt.

[ElbowMacaroni]

Thanks for the explanation, and the pics too. Very enlightening. Makes much more sense now. I guess my woodworking knowledge was getting in the way of my lock learning...LOL

-EM

[raimundo]

The modern deadbolt is designed to fit into easily prepared drillings, and it takes less wood from the door which in my opinion means it leaves the door stronger than a mortise lock where a large mechanism is buried (mortised) in the door.
there are drill rigs to help cut a mortise, but these still have to be finished with a chisel.

or am I wrong is there a new tool that make cutting mortises simple and quick?

[Tyler J. Thomas]

The modern deadbolt is designed to fit into easily prepared drillings, and it takes less wood from the door which in my opinion means it leaves the door stronger than a mortise lock where a large mechanism is buried (mortised) in the door.
there are drill rigs to help cut a mortise, but these still have to be finished with a chisel.

or am I wrong is there a new tool that make cutting mortises simple and quick?

They have jigs for routers that do nearly all the work but you're on the right track in regards to a door becoming weaker as more wood is removed from it. Walter Schlage kind of revolutionized the way locks were mounted on doors when he was able to improve upon the cylindrical lockset. The popularity of mortise locks in doors has been on the decline ever since.

[ElbowMacaroni]

Yeah, I do see how that could weaken a wooden door, but what about a metal clad house door? Would the weakening of the wood be mitigated by the casing on the door or well maybe I guess since the metal is often pretty thin, that the weakening of the wood might still affect it and the metal be subject to peeling back if enough force were used... guess I answered my own question while typing it... I suppose that's why I call people at work to bounce things off them, as I often find the answer comes to me when explaining the problem to someone else...

I suspect a thicker actual metal door might be suited to such a lock though, or is that assumption incorrect as well?

[Tyler J. Thomas]

Well, for what it's worth, a mortise lock inside of a metal door is really only going to be secured via two brackets that are tack welded into place. I've seen them in metal, commercial doors before as well as wooden doors. It's really all a matter of what the building designer specified, what the customer wanted, etc. and not so much as which is going to provide the most durability with regards to the rest of the door. As long as they aren't being kicked or rammed on a daily basis, they'll hold inside that door for the life of the building - no matter if it's wooden or metal.