From *Hobbit* <AWalker@RED.RUTGERS.EDU> 4-Nov-1987 01:10:52
Subj:  hotel deadbolt hacks
There are two ways to go about this.
The first method uses two little sprung pins mounted at about 10:00 and
2:00 in the back of the cylinder, just past the last pin. If the key
is turned to 4:00 or 8:00, the open bottom of the keyway exposes the
end of one of these pins, and it jumps out into the bottom of the keyway,
preventing further rotation. The pin is mounted at such an angle that
the plug can "retreat" from this wedged position, but not continue past
it. A key cut such that there is enough metal protruding past the last
pin will keep these pins up inside their holes, allowing full rotation.
The second method uses the last pin as a sort of switch. At the last pin
position the cylinder is machined out large enough to acommodate a ring,
which surrounds the rear end of the plug. This ring has a hole through it
for the last pin and a stub sticking off the back near the bottom. It is
also of a known thickness. Raising the rear pin to the normal plug shear
line will allow the plug to turn, but the ring remains stationary [held by
the driver]. At about 4:00 or 8:00, the tailpiece hits the ring's stub
and can't rotate any more. The master key raises the last pin to the
next level, such that the ring now turns with the plug, and doesn't impede
In either case, full rotation is required to shoot the deadbolt, but only
a quarter turn or so pulls the spring latch. Thus a guest key can't shoot
the deadbolt but the specially cut masters can.
If you're worried about people getting into your hotel room, carry your own
keyed cylinders with you and swap them when you arrive. Probably against
fire regs, but it works. When was the last time you found yourself inside
a burning hotel?
From Bill Sommerfeld <wesommer@ATHENA.MIT.EDU> 9-Nov-1987 21:39:13
Subj:  Re: hotel deadbolt hacks
> Probably against fire regs, but it works.
I don't see why; all that matters is that you be able to get OUT, not
that others be able to get in.. besides, fire fighters have a
reputation for using an axe when a doorknob would do.