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change wheel for which the combination is changed by moving the
screw which serves as a drive pin from one threaded hole in the
wheel to another. Also called a fixed pin hand change wheel.
SCREW EXTRACTOR A special tapered drill bit with long-
fluted, left-hand threads for removing broken screws. Also called
EZYOUT, after a trade name.
SCREWLESS KNOB A knob fastened to a spindle without
screws. SCRIBER - A sharp, pointed tool for marking lines on ma-
terials to be cut or measured.
SECOND GENERATION DUPLICATE A duplicate key made
by copying another duplicate key which was made from an original
key.
SECTIONAL KEYWAY One of a group of keyways, each with
individual but interrelated key sections, used for part of a master key
system, such as the floor of a building. See key section series.
SECTIONAL MASTER KEY A master key used in one sectional
keyway only as part of a master key system. See key section series.
SECTIONAL MASTER KEYING A method of master keying
by using the same combinations with a number of different key sec-
tions chosen in such a way that higher level master keys will fit into
the keyways of lower level master keys and their change keys, but
not vice versa.
SECTION MASTER KEY Another name for a level five master
key.
SECONDARY LOCK Any lock, usually a deadbolt lock, added
to a door to supplement an existing lock. Also called an auxiliary
lock.
SECURITY The ability of an enclosed area and the lock which
guards it to withstand unauthorized entry.
SEGMENT BOLT A curved springbolt which pivots instead of
A Dictionary of Locksmithing 59
sliding to cut down on friction when it hits the strike.
SEGMENT MASTER KEY Another name for a level three mas-
ter key.
SELECTIVE MASTER KEY A special master key set to operate
any lock in a master key system without cross-keying, such as an
engineer s key. Usually there are no more than two selective master
keys in a system. See also unassociated master keys.
SELVEDGE A name used in England for the face plate.
SEMI-MORTISE LOCK A lock which is cut into a door or
drawer so that it is flush with the surface but not entirely encircled
by the door or drawer as it would be if fully mortised.
SEPARATOR DISC See spacer.
SERIES WAFER One of the three types of wafer tumblers of a
popular cylindrical lock made by the Schlage Lock Co., designed so
that, when there is no key in the keyway, the series wafer stem, along
with the stem of the master wafer, sticks out of the plug to prevent
the plug from turning. Each such lock normally uses three series
wafers, but one or two of them can be removed for masterkeying.
See also combination wafer, master wafer and wafer tumbler.
SERVANT KEY The British name for a change key in a master
key system.
SET SCREW A screw used to hold part of a mechanism in place.
For example, a set screw, with access from the face plate, holds the
cylinder securely in a mortise lock case.
SET-UP KEY Another name for a safe deposit box neutral key.
SHACKLE The hinged or sliding link of a padlock, usually U-
shaped or curved and made of hardened steel.
SHACKLE CLEARANCE The distance between the top of a
padlock case and the highest inside point on the shackle when closed.
SHACKLE RETAINER A specially cut lamination of a lami-
nated padlock which keeps the heel of the shackle in place. Also,
a pin which holds the shackle heel in place in several types of pad-
locks.
60 A Dictionary of Locksmithing
SHACKLE SPRING The compression coil spring positioned un-
der the heel of a padlock shackle to push the free end of the shackle
out of the padlock when the locking dog retracts.
SHANK The section of a bit key between the bow and the shoul-
der. Also, the projecting stem of a knob which holds the end of the
spindle.
SHAVED BLADE A key blade with a curved bottom edge to fol-
low the contour of the cylinder plug circumference. Most original
key blanks have shaved blades. See also unshaved blade.
SHEAR LINE The space of several thousandths of an inch be-
tween a cylinder plug and its cylinder housing. The shear line is
completely unblocked only when the ends of the tumblers line up
with the circumference of the plug.
SHELL Another name for the housing of a lock.
SHIELD RING Another name for a burglar-proof guard ring.
SHIM A thin strip of metal, usually less than five thousandths of
an inch thick and one quarter of an inch wide, used in shimming
open a pin tumbler lock.
SHIMMING A technique of opening a pin tumbler cylinder by
inserting a shim from the rear across the shear line while withdraw-
ing a key blank from the keyway so that the shim can slip between
the bottom pins and the top pins.
SHIM WASHERS Washers used in locks to compensate for man-
ufacturing tolerances. Shim washers are placed, for example, on the
post of a lever tumbler lock to space the tumblers. They are also used
to space the wheels in combination locks.
SHOOT The throw of a springbolt; that is, the distance it travels.
SHOULDER A projection between the bow and the blade of a key
which limits the travel of the key into the keyway and from which
the positions of the key cuts on the blade are indexed. See also key
stop.
SHOULDER GUIDE That part on some key machines, shaped
like a two-pronged fork, which permits the operator to set with ease
A Dictionary of Locksmithing 61
the proper spacing between the shoulders of the sample key and the
key blank as they are clamped in the key machine vises. The shoul-
der guide is mounted on a pivot so it can be pushed out of the way
during the cutting of the key. Also called a gage fork.
SHUT-OUT A setting on hotel function locks, operated by a
thumbturn or push-button from the inside or by a display room key
or emergency key from the outside, which renders the guest room
key and all other master keys except the emergency key inoperative.
SHUT-OUT KEY A key to permit the management of a hotel to
lock a door against the use of all other keys except an emergency
key.
SHUTTER The spring-loaded part of a dust cap on an automobile
door or trunk lock which actually covers the keyhole and which is
pushed out of the way when the key is inserted. See also keyway
shutter.
SIDEBAR A metal bar which protrudes from the side of certain
cylinder plugs and crosses the shear line when the correct key is not
in use to prevent the plug from turning, performing the same function
as the tumblers of a standard cylinder when they cross the shear line.
SIDEBAR CYLINDER A disc tumbler cylinder with a spring-
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