Open bottom of keyways

[vector40]

Just as a construction question, does anyone know the REASON why the bottom side of the keyway is usually open (hence the classic oh-no-my-drivers-are-stuck problem)? Is it just part of the manufacturing process, or is there a reason for it?

[Chrispy]

To make more room for the key. And also, plugs are typically cast in halves. Any other reasons guys?

[keysman]

To make more room for the key. And also, plugs are typically cast in halves. Any other reasons guys?

Most lock plugs are NOT "cast " in halves, most are extruded from a billett of solid material. The "open " bottom is a 'way out" for the removed material. Perhaps one of the machinists here can give a better explaination
There may be a few exceptions to the "cast in 2 pieces" for locks made out of Pot metal. ie Most automotive locks and cheep cam locks.

[Mad Mick]

Perhaps one of the machinists here can give a better explanation.

Shrub, Shrub, wherefore art thou Shrub?

[Chrispy]

Most lock plugs are NOT "cast " in halves, most are extruded from a billett of solid material. The "open " bottom is a 'way out" for the removed material. Perhaps one of the machinists here can give a better explaination
There may be a few exceptions to the "cast in 2 pieces" for locks made out of Pot metal. ie Most automotive locks and cheep cam locks.

Fair enough. Some of the locks I've taken apart have two-piece plugs. Not all, but some, hence the highlighted "most" and "few exceptions".

[fixer]

:?:

To make more room for the key. And also, plugs are typically cast in halves. Any other reasons guys?

Most lock plugs are NOT "cast " in halves, most are extruded from a billett of solid material. The "open " bottom is a 'way out" for the removed material. Perhaps one of the machinists here can give a better explaination
There may be a few exceptions to the "cast in 2 pieces" for locks made out of Pot metal. ie Most automotive locks and cheep cam locks.

Brass lock plugs are made by 'broaching'. This involves running the plug along a series of cutters that form the keyway. The plug starts off as a solid chunk of brass though.

It is possible that the cheap plugs are cast, but I can't say for sure as I have not seen them being made.

[raimundo]

The broach for a keyway is like a hacksaw blade that is not flat, but is shaped like the keyway, and it is tapered from the start, so that it comes out of the the table of the tool, just gradually, picture a hack saw blade that is angled to nothing at one end, and as the plug is pushed along this the teeth invade into the solid material gradually, the chip is removed either by large round holes in the blade or the blade is actually in segments with gaps between. If anyone has seen the machines (when schlage was in sanfrancisco years ago they gave locksmiths a tour) tell us where