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CROSS REFERENCE TO OTHER APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/031,264, filed Feb. 21, 2011. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to cylinder locks, and particularly to a key blank, key and cylinder lock with reduced manufacturing and inventory costs. 
     BACKGROUND OF THE INVENTION 
     As is well known in the prior art, with reference to  FIGS. 1 and 2 , many cylinder locks include a plug  1  (also called a tumbler) arranged for rotation in a body  2  wherein the plug  1  and the body  2  are provided with a number of bores  3  and  4 , respectively, in which plug pins and driver pins are disposed. The plug  1  is formed with a keyway for inserting therein a key  5 . The driver pins are aligned with the plug pins, and the plug and driver pins have varying lengths that define a key cut combination. Upon insertion of a key with the correct key cut combination, the faces of the plug pins and driver pins that touch each other are aligned flush with the circumferential surface of the plug  1 , referred to as the shear line, and the plug  1  may be rotated to actuate the lock. If the key cut combination is not correct, at least one of the driver and plug pins will cross over the shear line and prevent rotation of the plug  1 , and thus prevent actuation of the lock. 
       FIGS. 1 and 2  show a European profile double cylinder lock. The cylinder lock actuates a common cam  6 , which fits in a recess  7  formed in the body. The plug  1  may be formed with a longitudinal groove  8  for the key. Different holes  9  may be formed in the plug  1  and the body  2  for placing therein hardened, anti-drilling pins (not shown). 
     It is common to construct the plug  1  and body  2  from relatively soft metals, such as brass, although other metals are also used, such as different steel alloys. The plug and body are generally made by various machining manufacturing steps. It would be desirable to reduce manufacturing costs for making the cylinder lock. 
     The key is commonly made from metal, such as nickel silver or brass, but other metals are also used. The key is generally made in a coining or stamping process, whereas keyway profiles, key cuts and other features on the key are generally made by machining. Some cylinder locks come in different lengths, and the cylinder locksmith or installer has to select the proper cylinder length to match the dimensions of the door thickness. In addition, the inner side of the door often has a turning knob, that is, it is not operated by a key. These considerations increase inventory costs for different lengths of cylinder locks, and increase the difficulty of installation for the cylinder locksmith; sometimes the cylinder locksmith has to come twice to the customer—once to get the proper dimensions for installation and another time to actually install the cylinder lock. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide a key blank, key and cylinder lock with reduced manufacturing and inventory costs, and with improved quality and security, as is described in detail further hereinbelow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: 
         FIGS. 1 and 2  are simplified pictorial and exploded illustrations, respectively, of a prior art European profile double cylinder lock; 
         FIGS. 3 and 4  are simplified pictorial and exploded illustrations, respectively, of a cylinder lock, constructed and operative in accordance with an embodiment of the present invention, employing plug locking elements which are disc tumblers disposed in a plug; 
         FIGS. 5A and 5B  are two simplified perspective illustrations of a first half-shell that makes up part of the cylinder lock body of the cylinder lock of  FIG. 3 ; 
         FIG. 6  is a simplified perspective illustration of the plug of the cylinder lock of  FIG. 3 ; 
         FIGS. 7A and 7B  are two simplified perspective illustrations of a second half-shell that makes up part of the cylinder lock body of the cylinder lock of  FIG. 3 ; 
         FIG. 8  is a simplified perspective illustration of a body chassis of the cylinder lock of  FIG. 3 ; 
         FIG. 9  is another simplified perspective illustration of the plug, showing chambers for receiving therein plug locking elements; 
         FIGS. 10 and 11  are simplified life-size and enlarged illustrations, respectively, of a key shaft of a key used to operate the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention; 
         FIGS. 12 and 13  are simplified life-size and enlarged illustrations, respectively, of a pair of movable security catches used in the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention; 
         FIGS. 14 and 15  are simplified life-size and enlarged illustrations, respectively, of a side bar used in the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention; 
         FIGS. 16 ,  17 A and  17 B are simplified life-size and two enlarged illustrations, respectively, of a plug locking element used in the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention; 
         FIGS. 18 ,  19 A and  19 B are simplified life-size and two enlarged illustrations, respectively, of a key head of the key used to operate the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention; 
         FIGS. 20 ,  21  and  22  are simplified sectional illustrations of three different positions of the key inserted into the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention, taken along section lines A-A in  FIG. 25 ; 
         FIGS. 23 and 24  are simplified pictorial and enlarged illustrations, respectively, of the key interfacing with the movable security catches and with a securing element that turns the key into a turning knob for use on the inside of the door, in accordance with an embodiment of the present invention; 
         FIG. 25  is a simplified pictorial illustration of the key inserted into the cylinder plug; 
         FIGS. 26 and 27  are simplified sectional and enlarged sectional illustrations, respectively, of the key inserted into the cylinder plug, taken along section lines B-B in  FIG. 25 , and showing an adjustable position of the key head, abutting against the plug and interfacing with a coupling of the cylinder lock; 
         FIGS. 28-32  are simplified sectional illustrations of five (5) different positions of the key inserted into the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention, taken along section lines C-C in  FIG. 25 , and showing operation of the movable security catches; 
         FIG. 33  is another simplified pictorial illustration of the key inserted into the cylinder lock of  FIG. 3 ; 
         FIG. 34  is a simplified sectional illustration of the key inserted into the cylinder lock, fully turned and poised to rotate the plug to actuate the cylinder lock, taken along section lines D-D in  FIG. 33 ; 
         FIGS. 35-39  are simplified sectional illustrations of five (5) different positions of the key inserted into the cylinder lock, in accordance with an embodiment of the present invention, taken along section lines E-E in  FIG. 33 ; 
         FIG. 35A  is an enlarged sectional illustration of the sidebar with respect to recesses formed in the plug locking element, in accordance with an embodiment of the present invention, showing anti-cylinder lock-picking notches; 
         FIG. 40  is a simplified pictorial illustration of the key shaft; 
         FIG. 41  is a simplified sectional illustration of the key shaft, taken along section lines F-F in  FIG. 40 ; 
         FIG. 42  is another simplified pictorial illustration of the key shaft, showing the lateral recess for changing the key into a turning knob; 
         FIG. 43  is a simplified pictorial illustration of the plug locking elements interfacing with key cuts formed on the key shaft; 
         FIG. 44  is an enlarged pictorial illustration of the plug locking elements interfacing with key cuts formed on the key shaft; 
         FIG. 45  is a simplified pictorial illustration of one of the plug locking elements; 
         FIG. 46  is another enlarged pictorial illustration of the plug locking elements interfacing with key cuts formed on the key shaft; 
         FIG. 47  is a simplified pictorial illustration of a key configured as a knob on the inside of the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention; 
         FIG. 48  is a simplified pictorial illustration of a bushing, rosette and escutcheon used on the outside of the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention; 
         FIG. 49  is a simplified pictorial illustration of the knob of  FIG. 47  with a rosette on the inside of the cylinder lock, in accordance with an embodiment of the present invention; 
         FIG. 50  is a simplified pictorial illustration of a mortise lock in a door, showing the inside and outside of the cylinder lock of the present invention, in accordance with an embodiment of the present invention; 
         FIGS. 51 and 52  are simplified pictorial and exploded illustrations, respectively, of a cylinder lock, constructed and operative in accordance with an embodiment of the present invention, employing plug locking elements which are wafers (also called wafer tumblers or slider tumblers); 
         FIGS. 53 and 54  are simplified pictorial and exploded illustrations, respectively, of a cylinder lock, constructed and operative in accordance with an embodiment of the present invention, employing plug locking elements which are telescoping pins; 
         FIG. 55  is a sectional, pictorial illustration of a section of one of the half-shells of the cylinder lock of  FIG. 53 , taken along section lines G-G in  FIG. 54 ; 
         FIGS. 56 and 57  are simplified pictorial and exploded illustrations, respectively, of a cylinder lock, constructed and operative in accordance with an embodiment of the present invention, employing plug locking elements which are in-line pins; 
         FIGS. 58 ,  59  and  60  are simplified pictorial, sectional and exploded illustrations, respectively, of a cylinder lock, constructed and operative in accordance with an embodiment of the present invention, wherein the cylinder lock is an American mortise cylinder lock with a threaded lock body; 
         FIG. 61  is a simplified pictorial illustration of a key cutting machine of the prior art; 
         FIG. 62  is a simplified side-view illustration of the key cutting machine of  FIG. 61 ; 
         FIG. 63  is an enlarged illustration of a key holder to which the key is affixed in the key cutting machine of  FIG. 61 ; 
         FIG. 64  is an enlarged illustration of a given key whose key cut codes are to be sensed for duplication; 
         FIG. 65  is a partially cutaway illustration of a key cut code reading device in the key cutting machine of  FIG. 61 ; 
         FIG. 66  is a simplified pictorial illustration of a key cutting machine, constructed and operative in accordance with an embodiment of the present invention; 
         FIG. 67  is an enlarged illustration of a key holder of the key cutting machine of  FIG. 66 ; 
         FIG. 68  is a simplified side-view illustration of the key cutting machine of  FIG. 66 ; 
         FIG. 69  is an enlarged illustration of the key holder holding a key of the present invention in the key cutting machine of  FIG. 66 ; 
         FIG. 70  is an enlarged illustration clearly showing the impossibility of reading the key cut code of the key of the present invention if the prior art key cut code reading device of the prior art key cutting machine is used with the key cutting machine of the present invention; 
         FIGS. 71 and 72  are pictorial illustrations of the key holder of the prior art, respectively with and without a key affixed therein; 
         FIGS. 73 and 74  are pictorial illustrations of the key holder of the present invention, respectively with and without a key affixed therein; 
         FIGS. 75 and 76  are pictorial and enlarged side-view illustrations, respectively, of the key holder of the present invention, with a conventional key affixed therein; and 
         FIGS. 77 and 78  are pictorial and enlarged side-view illustrations, respectively, of the key holder of the present invention, with a key of the present invention affixed therein. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     It is noted that the terms “upper”, “lower”, “above”, “below”, “left” and “right”, and the like, only refer to the sense of the drawings and do not limit the invention in any way. 
     It is further noted that ends of the plug are defined as follows: the “key insertion” end or the “proximal” end of the plug is the end facing the user for inserting the key into the keyway; the “distal” end is opposite to the key insertion end. The proximal and distal ends of the key correspond to the proximal and distal ends of the plug when the key is fully inserted into the plug. 
     Reference is now made to  FIGS. 3 and 4 , which illustrate a cylinder lock  10 , constructed and operative in accordance with a non-limiting embodiment of the present invention. The major components of cylinder lock  10  may be made by MIM, e.g., using a steel alloy, e.g., a stainless steel alloy, such as but not limited to, 17-4PH, a precipitation hardening martensitic stainless steel. The illustrated embodiment is for a European profile double cylinder lock, but it is understood that the invention is not limited to such a cylinder lock. 
     In the illustrated embodiment, the body of cylinder lock  10  includes a chassis  12 , and two half-shells  14  and  16  (which are the same for both sides of the double cylinder lock). The invention is not limited to just two shells and any number is also possible. Accordingly the general term “shell” is also used to refer to half-shell, third-shell, etc. 
     Chassis  12   
     Reference is additionally made to  FIG. 8 . Chassis  12  includes an elongate lower rib  18 , from an end of which extends an upright end face  20 . An inner abutment  22  extends from both lower rib  18  and end face  20 . Abutment  22  is formed with mounting holes  24 . In the final assembly, end face  20  forms the lower part of the standard European profile. Abutment  22  is formed with upper axial groove  48  for receiving therein a side bar  50 , which is described further below with reference to  FIGS. 14 and 15 . Side bar  50  is shown in  FIG. 4  with two biasing devices  52 , such as two small coil springs. 
     Half-Shells  14  and  16   
     Reference is additionally made to  FIGS. 5A ,  5 B,  7 A and  7 B. The half-shells  14  and  16  each include a lower side wall  26 . One of the half-shells ( 14 , in the illustration) is formed with tapped holes  28  and the other half-shell ( 16 ) is formed with through holes  30 , which may be countersunk. Mechanical fasteners  32  ( FIGS. 3 and 4 ), e.g., flat head screws, are used to secure the two half-shells  14  and  16  to one another. The half-shells  14  and  16  each include an upper half-cylindrical wall  34  extending from lower side wall  26 . Half-cylindrical wall  34  is formed with a partially circumferential groove  36  which ends in two axial notches  38 . A small recess  40  may be formed at the end of groove  36  between notches  38 . 
     A resilient clasp  42  ( FIGS. 3 and 4 ), formed with two outwardly extending tabs  44  at ends thereof, fits into groove  36  in the final assembly to affix the two half-shells  14  and  16  to one another. Tabs  44  fit into notches  38 . A small tool (e.g., small flat blade screwdriver, not shown) can be inserted in recess  40  to dislodge clasp  42  from groove  36  for disassembly, if needed. In the final assembly, the pair of half-cylindrical walls  34  form the upper part of the standard European profile cylinder lock. An access hole  46  may be formed at an end of one or both of the half-cylindrical walls  34  for inserting therethrough a fastener (e.g., set screw)  47  for changing the key into a turn knob, as will be explained further below. A trap groove  49  ( FIGS. 5B and 7B ) may be formed on the inner side of the half-cylindrical walls  34  for receiving therein movable security catches  96  described further below with reference to  FIG. 28 . 
     It is noted that mechanical fasteners  32  and clasp  42  are just one example of fasteners for fastening the half-shells  14  and  16  together, and other fasteners can be used, such as but not limited to, circlips, retaining rings, snap rings, rivets and many others. It is noted that clasps  42  are optional and the lock halves may be fastened sufficiently without them. 
     It is noted that the cylinder lock body can be constructed of two half-shells without a chassis, by reshaping the two half-shells to include the lower rib and the end face, for example. It is also noted that the parts for the inner side and outer side of the cylinder lock are preferably identical to reduce manufacturing and inventory costs. 
     Plug  54   
     Reference is additionally made to  FIGS. 6 and 9 . Cylinder lock  10  includes a plug  54  which includes a plurality of chambers  56 , separated by walls  58 , for receiving therein plug locking elements  60  (not shown here, and are described more in detail hereinbelow). Chambers  56  may be of equal width or may have different widths. For example, in the illustrated embodiment, there are five chambers  56 ; four chambers are sized to receive therein three plug locking elements or two plug locking elements and a pair of movable security catches, and another chamber sized to receive therein two plug locking elements with no movable security catches. 
     Of course, the invention is not limited to these configurations. A threaded hole  62  ( FIG. 6 ) may be formed at an end of plug  54  for receiving fastener  47  ( FIG. 4 ) that changes the key into a turn knob, as will be explained further below. 
       FIGS. 6 and 9  show the distal end  57  of plug  54 , which is the end opposite to the key insertion end  55 , also called keyway  55 . As seen in  FIGS. 6 ,  9  and  20 , bearing surfaces  64  are formed for supporting the key as it turns, as described further below. The bearing surfaces  64  may include diametrically opposed upper and lower arcuate surfaces  21  and  23 , and diametrically opposed arcuate ears  29 . Upper and lower arcuate surfaces  21  and  23  terminate in upper and lower key abutment surfaces  65  and  67 , respectively. 
     The distal end  57  of the plug  54  is formed with a recess  66  ( FIG. 6 ) for receiving therein a spring-loaded coupling  68  ( FIGS. 4 ,  26  and  27 ) and two blind holes  70  for receiving therein springs  72  ( FIGS. 4 and 27 ) of the coupling  68 . As seen in  FIG. 9 , holes  74  are formed in a distal end wall  75 , for receiving therein the pivoting portion of the movable security catches  96 , described below with reference to  FIG. 13 . Coupling  68  interfaces with a standard cam  76  ( FIGS. 3 and 4 ), and other kinds of cams, as is well known in the art. 
     Plug  54  is formed with an abutment  73  (seen in  FIG. 27 ) for the key to abut against, as is explained below. As seen in  FIG. 20 , plug  54  is also formed with a lower recess  63 , for receiving therein side bar  50 . 
     Manufacture of Cylinder Lock Body and Plug 
     Metal injection molding (MIM) is a manufacturing technique for making complex machined or investment cast parts. MIM merges injection molding and powdered metal technologies by blending a polymer with an extremely fine metal powder. The blended material is then melted and injection molded to produce intricately formed parts that are repeatable in high production manufacturing. 
     In the MIM method, a metal-filled or a metallic powder-filled plastic is injected into a mold. Upon removal from the mold, the part still has in it plastic binders and the part is called a “green part”. The part is then cured, cooled and the plastic binding matrix is removed from between the metal particles. The part is then sintered, and due to the fine powders used, the density of the molded component dramatically increases. Afterwards, MIM components can have mechanical, wear, and corrosion resistance properties equivalent to machined material. 
     The cylinder lock body (chassis  12  and half-shells  14  and  16 ) and plug  54  may be preferably made by MIM, e.g., using a stainless steel alloy, such as but not limited to, 17-4PH, a precipitation hardening martensitic stainless steel. Most of these parts have low weight (e.g., not more than 50 g) and substantially uniform wall thickness (including the walls  58  of plug  54 ). The investment in molds for the MIM process can be significantly less (10% of the cost) than the investment in transfer machines commonly used in making brass cylinder locks. With the MIM process, one can manufacture a cylinder lock out of hardened metal, such as steel, as opposed to the weaker brass. However, even though MIM is preferred for reducing costs and maintaining good manufacturing tolerances, it is recognized that all of the parts may be made by other methods, such as machining. 
     Key Blank/Key  80   
     Reference is now made to  FIGS. 3 ,  4 ,  10 ,  11 ,  26  and  27 , which illustrate a key shaft  78  of a key  80  used to operate the cylinder lock of  FIG. 3 , in accordance with an embodiment of the present invention. Before any key cuts are made, key  80  is also referred to as key blank  80 , and the terms key and key blank will be used interchangeably throughout the specification and claims, except for when the key cuts are discussed, at which time it is a key and not a key blank. Key shaft  78  may be made of metal, such as but not limited to, cold drawn nickel silver; alternatively, key shaft  78  may be made by MIM. A key head  79  is provided, made of metal or plastic, and is also shown in  FIGS. 18 ,  19 A and  19 B. If made of metal, key head  79  can be made by MIM; if made of plastic, it may be made by injection molding, for example. 
     A reference abutting structure  82  is formed at a distal portion of key shaft  78 , such as a flat surface formed at the distal end of a rail portion  84  of key shaft  78 . The reference abutting structure  82  abuts against abutment  73  of plug  54 , as clearly seen in  FIGS. 9 ,  25 ,  26  and  27 . The axial positions for making key cuts  86  along shaft  78  of the key blank  80  (shown as dimensions A 1 -A 5  in  FIG. 26 , although the invention is not limited to five key cut positions) are defined with respect to reference abutting structure  82 . This also means that the axial positions for the plug locking elements  60  (described below), which correspond to the same axial positions of the corresponding key cuts  86 , are defined with respect to reference abutting structure  82 . This is in contrast with the prior art, in which the positions of the key cuts are defined from the proximal end of the key, not the distal end. 
     Since the key cuts  86  of the present invention are referenced with respect to the distally located reference abutting structure  82 , the proximal end of the key shaft  78  can protrude towards the proximal end (i.e., outwards towards the user away from the cylinder lock) at any desired length. As seen clearly in  FIG. 26 , this enables the key  80  to have an adjustable length as measured from the proximal end of key head  79  to the distal end of the key  80 . One of way of achieving this is by forming key head  79  with a channel  88  in which the proximal end of key shaft  78  is inserted. The key shaft  78  simply slides in channel  88  and key head  79  is secured at the desired length with a fastener (e.g., set screw)  90 . Channel  88  may be a blind channel as illustrated in  FIG. 26 . Alternatively, channel  88  may open through the proximal end of the key head  79  (as indicated by broken lines  31  in  FIG. 26 ), wherein key shaft  78  passes through key head  79  and is cut flush with the proximal end of key head  79 . 
     Key shaft  78  is formed with a lateral recess  92  into which is received fastener  47 . The way in which fastener  47  turns the key  80  into a turning knob is explained further below with reference to  FIG. 24 . 
     Key shaft  78  is formed with an actuating structure  94 , such as one or more laterally protruding surfaces formed near or on a flat surface of a rail portion  84  of key shaft  78 . The actuating structure  94  actuates movable security catches  96 , as will be explained further below with reference to  FIGS. 28-32 . 
     It is noted that there are prior art keys with key cuts that can be identified simply by visual inspection by an experienced individual. Unscrupulous individuals can copy keys in this way without even physically copying the original key; they know the key code by visual inspection alone and cut this key code in a key blank. In contrast, in the present invention, key cuts  86  have features that look different than the prior art and make knowing the key code by visual inspection extremely difficult. First, the key cuts  86  are made at an angle, which is difficult to identify by mere visual inspection. Second, the shallowest possible key cut is not a cut that merely “skims” the surface (which would be easily recognizable as the shallowest possible cut for the particular set of possible key cuts); rather it is a bona fide key cut that is definitely not flush with the surface of key shaft  78  and whose depth is not easily discernible as the shallowest possible cut. 
     Master Keying 
     In the prior art, there is a limited, finite space in a cylinder lock plug for adding master key elements. This is a disadvantage, especially in large modern lock systems that have several hierarchical levels, such as a grand-master key blank at the top level of the system, one or more master key blanks at a medium level and several change key blanks at the lowest level. The additional master key elements add complexity to the assembly, can jam and lower security against picking. 
     The key of the present invention can easily be integrated in a master key system, with any hierarchy of master or grand-master keys and change keys. In an example of one system, different sets of movable security catches (pairs of catches on both sides of the key or even a single catch on one side of the key) may be placed in the plug. The master or grand-master key can be formed with one combination of actuating structure  94  that actuates all of the movable security catches, whereas the lower hierarchical level keys can be made to actuate only some of the catches. This may be accomplished by simply filing, grinding or otherwise voiding places on the actuating structure  94  of the lower hierarchical level keys so that the altered places cannot actuate the movable security catches. This altering procedure may be done on or off site. In addition, because the invention allows asymmetrical placing of movable security catches (e.g., one movable security catch one side of the key), it is possible to make a lower hierarchical level key that can only lock but not unlock, or vice versa, only unlock but not lock. There is no need for additional master key elements. 
     Movable Security Catches  96   
     Reference is now made to  FIGS. 12 and 13 . Each movable security catch  96  pivots on a pivot  98  which fit into hole  74  ( FIG. 9 ) of plug  54 . (The pair of movable security catches  96  are minor images of each other.) Each movable security catch  96  is biased by a biasing device  99 , e.g., a coil spring ( FIGS. 4 ,  23  and  28 - 32 ), which fits on a prong  100  jutting from security catch  96 . Each movable security catch  96  has an annular claw  102  that extends radially outwards from pivot  98 , and an arcuate key abutting surface  104  that extends radially inwards from pivot  98 . Movable security catches  96  may be made by MIM. 
     It is noted that this is just one example of movable security catches  96  and other security catches can be employed to carry out the invention, such as security catches which slide. 
     More than one set of movable security catches  96  may be provided and they may be located anywhere along the plug  54 . For example,  FIGS. 5B and 7B  show that trap grooves  49  may be formed along a plurality of positions on the inner side of the half-cylindrical walls  34  for receiving therein one or more sets of movable security catches  96 .  FIG. 24  shows an example of more than one set of movable security catches  96 . 
     Side Bar  50   
     Reference is now made to  FIGS. 14 and 15 , which illustrate side bar  50 . Side bar  50  has elongate ridges  106 , which can get caught on plug locking elements  60  to make picking difficult, as is described further below. Biasing devices  52  ( FIG. 4 ) are mounted on two lugs  108  on side bar  50 . Side bar  50  may be made by MIM and hardened. It is noted that all parts in the present invention which are made by MIM may be hardened; however, if a riveting operation is to be performed on the part, it is preferable not to harden the metal. 
     Plug Locking Element  60   
     Reference is now made to  FIGS. 16 ,  17 A and  17 B, which illustrate plug locking element  60 . In this embodiment, plug locking element  60  is a disk that partially rotates about the longitudinal axis of the plug  54 . Plug locking element  60  has a round body  110  formed with a plurality of inner bearing surfaces  112  for the key  80  to slide and turn against. The inner bearing surfaces  112  may include diametrically opposed upper and lower arcuate surfaces  113  and diametrically opposed arcuate ears  114 . Plug locking element  60  has a crown portion  115  extending from an upper portion of round body  110 . The junction of crown portion  115  with round body  110  defines two (left and right) inner shoulders  116  which can abut against shoulders  103  ( FIG. 35 ) of plug  54  only when manipulated by a tool other than the key. Key cut interface probes  118  are formed on inner surfaces of plug locking element  60 ; probes  118  interface with the key cuts  86 , as will be explained further below. Side bar receiving grooves  120  are formed on the lower outer contour of round body  110 . The grooves  120  may be separated from one another by a portion of round body  110  on which peripheral trap notches  122  are formed. The elongate ridges  106  ( FIG. 15 ) of side bar  50  can get caught in notches  122  to make picking difficult, as is described below with reference to  FIG. 35A . 
     Inner Key Can Serve as Turning Knob 
     Reference is now made to  FIGS. 23 and 24 , which shows fastener  47  received in lateral recess  92  of key shaft  78 . Fastener  47  is not tightened completely against key shaft  78 ; rather key shaft  78  can turn and slide with respect to fastener  47  up to the limits defined by the boundaries of lateral recess  92 . Recess  92  is preferably formed on all keys, regardless of whether the key is used as a knob or not. Accordingly, fastener  47  permits axial movement of the inner key up to the proximal end wall of lateral recess  92 , meaning the key cannot be removed from the cylinder lock. Thus the key serves as a turning knob on the inside of the door. The permitted axial movement has another purpose: it allows a user to insert a key in the plug on the outside of the door, turn the key (since it has the correct key cuts), and push the coupling  68  in order to connect with cam  76  ( FIG. 4 ) and operate the cylinder lock, all this despite the presence of the turn-knob key on the inside of the door. In other words, the permitted axial movement permits the coupling  68  to move axially to connect with cam  76 . (The capability of moving the coupling  68  axially may also be seen by examining  FIGS. 26 and 27 .) 
     After returning key  80  to the vertical position, biasing device  72  pushes key  80  in the direction out of the plug  54 ; this spring force helps to pull the key  80  out of the plug  54 . It is noted that the key  80  does not have to be perfectly vertical in order to remove it from plug  54 . This is due to the key cuts  86  having slanted walls and to the biasing force (that is, the spring or urging force) of the biasing devices  52  of the side bar  50 . 
       FIG. 47  illustrates that the key head can be fashioned as a knob  79 K on the inside of the cylinder lock, in accordance with an embodiment of the present invention. The axial adjustment of knob  79 K along key shaft  78  can be substantial, such as but not limited to, 33 mm. Again, the key head does not have to be fashioned as knob  79 K and a regular key head  79  can serve as the turning knob. 
     Operation of Cylinder Lock with Key having Correct Key Cuts 
     Reference is now made to  FIGS. 20 ,  21  and  22 , which illustrate key  80  inserted into plug  54 . Key  80  is fully inserted in plug  54 , and in  FIG. 20  has not yet been turned. The key cut interface probes  118  have abutted against key cuts  86  (not shown here, but seen in  FIGS. 40-46  described a few paragraphs below), and the key  80  can be turned either counterclockwise ( FIG. 21 ) or clockwise ( FIG. 22 ). The upper and lower parts of the key profile can abut against the upper and lower key abutment surfaces  65  and  67 , respectively, upon turning the key; however, the key can be turned further only if the key has the correct key cuts. The further turning of the key  80  causes the plug  54  to rotate either counterclockwise or clockwise, by moving movable security catches  96  out of trap grooves  49  and side bar  50  into grooves  120 , as is explained now with reference to  FIGS. 28-32 . It is noted that movable security catches  96  can be placed anywhere in the wider chambers  56  of plug  54 . There can be more than one pair of catches  96  on both sides of the key  80  or even a single catch  96  on one side of the key  80 . 
     Reference is now made to  FIGS. 28-32 . In  FIG. 28 , key  80  has been inserted in the cylinder lock but has not yet been turned. The annular claw  102  of security catch  96  is initially trapped in trap groove  49 . In  FIG. 29 , key  80  with the correct key cut combination has been turned counterclockwise. A portion of the key pushes against the key abutting surface  104  of the right movable security catch  96 , compressing its biasing device  99 . The right security catch  96  pivots about pivot  98  and its annular claw  102  moves out of trap groove  49 . The key  80  can now turn plug  54  fully in the counterclockwise direction (to  FIG. 30 ), because the right security catch  96  no longer blocks rotation of the plug  54 ; the left security catch  96  also does not prevent rotation of the plug  54  because its annular claw  102  is free to move out of its trap groove  49  when plug  54  is turned counterclockwise (the heel of claw  102  simply slides out of the groove  49 ). Conversely, in  FIG. 31 , key  80  with the correct key cut combination has been turned clockwise. A portion of the key pushes against the key abutting surface  104  of the left movable security catch  96 , compressing its biasing device  99 . The left security catch  96  pivots about pivot  98  and its annular claw  102  moves out of trap groove  49 . The key  80  can now turn plug  54  fully in the clockwise direction (to  FIG. 32 ), because the left security catch  96  no longer blocks rotation of the plug  54 ; the right security catch  96  also does not prevent rotation of the plug  54  because its annular claw  102  is free to move out of its trap groove  49  when plug  54  is turned clockwise. 
     Reference is now made additionally to  FIGS. 33-39 . These figures illustrate another section of the key inserted and turned in the cylinder lock. As mentioned before, one can clearly see (especially noted in  FIG. 35 ) that the key cuts  86  can be asymmetrical, that is, different key cuts can be made on the two sides of the key. 
     Upon rotation of the plug locking elements  60 , as seen in  FIGS. 37-39 , side bar  50  enters one of the side bar receiving grooves  120  of plug locking elements  60 . Side bar  50  then does not prevent rotation of the plug  54 . 
     Referring to  FIG. 35A , it is seen that the elongate ridges  106  of side bar  50  can get caught in notches  122  of plug locking elements  60  if a would-be cylinder lock picker were to apply a torque on plug  54  and try to move the plug locking elements  60  to the shear line (that is, the positions that permit rotating plug  54 ). 
     Reference is now made to  FIGS. 40-46 , which illustrate the key cut interface probes  118  of plug locking elements  60  interfacing with key cuts  86  formed on the key shaft  78  of key  80 . For the sake of clarity, the crown portions  115  have been removed from plug locking elements  60  to better show key cut interface probes  118  interfacing with key cuts  86 . It is seen in  FIG. 41 , that the key cuts  86  can be asymmetrical, that is, different key cuts can be made on the two sides of the key. The key cuts  86  may be angled 11.5° from the vertical as shown, but the invention is not limited to this angle. 
     One Possible Door Installation 
     Reference is now made to  FIGS. 47-50 .  FIG. 50  illustrates a mortise lock  174  in a door  175 , showing the inside (right side in the drawing) and outside of the cylinder lock  10 . Door  175  may have a greater thickness than typical doors because of the addition of decorative panels  171 , and yet the same cylinder lock used for thinner doors can be used with this thicker door, as is now explained. 
     As mentioned before,  FIG. 47  illustrates that the key head can be fashioned as knob  79 K on the inner side of the cylinder lock (right side of  FIG. 50 ). Knob  79 K is rotatingly supported in an opening  123  formed in a rosette  124  ( FIGS. 49 and 50 ) on the inside of the cylinder lock. The outer side of the cylinder lock (left side of  FIG. 50 ) is operated by key  80 , which is rotatingly supported in a bushing  126 , which fits and turns in a rosette  128 , which fits in an escutcheon  130  ( FIG. 48 ). Bushing  126  may be easily removed from and re-installed in rosette  128 , which may be easily removed from and re-installed in escutcheon  130 . Key shaft  78  fits through a keyway opening  125  formed in bushing  126 . The rosette assembly (rosette  124  or the combination of bushing  126  rotating in rosette  128 ) serves as a bearing for rotatingly supporting key  80 , no matter how far the cylinder lock is distanced from the key head  79  or  79 K. Since the key head  79  is adjustable along the length of key  80 , key head  79  may be distanced much farther from the keyway than the prior art cylinder locks, which makes picking and tampering even more difficult. The dimensions shown in  FIG. 50  are exemplary and the invention is not limited to these values. 
     Of course, the regular key  80  with its key head  79  can also serve as the knob. Thus the key  80  is reversible—it can be employed as a turning knob and switched to being a regular (non-knob) key and vice versa. This of course means the cylinder lock is reversible, too. 
     The invention can provide very significant savings in inventory, installation and logistics for lock providers/installers. With the present invention, since the key length is adjustable by sliding the key head on the shaft, one cylinder lock is installable in a wide variety of door thicknesses; indeed, the dimensions of the door thickness is not important with this feature. One can easily choose between a knob or key at the inside of the door and the choice is reversible. 
     Other Kinds of Plug Locking Elements 
     In the following figures, other kinds of plug locking elements are described. The plug locking elements are still disposed in “chambers”; these chambers may be holes or other kinds of openings. 
     Reference is now made to  FIGS. 51 and 52 , which illustrate a cylinder lock that employs plug locking elements which are wafers  132 , which may be formed with a notch  134  for side bar  50 . Examples of such plug locking elements are the sliders in U.S. Pat. No. 4,977,767 (assigned to EVVA), and the terms “wafer” and “slider” are used interchangeably. In operation of the cylinder lock, the wafers or sliders  132  move in and out of grooves or recesses  139  formed in the shells. These recesses are quite difficult to make with prior art techniques, but are easier and cheaper to make with the technique of MIM of the present invention. 
     Reference is now made to  FIGS. 53 ,  54  and  55 , which illustrate a cylinder lock that employs plug locking elements which are multi-element pins or telescoping pins, in the style of MUL-T-LOCK cylinder locks (such as that described in U.S. Pat. Nos. 4,856,309, 5,123,268, 5,520,035, 5,784,910, 5,839,308, 7,647,799 and 7,698,921). In the illustrated embodiment, there are outer telescoping plug pins  136  with inner telescoping plug pins  136 A, and outer telescoping driver pins  138  with inner telescoping plug pins  138 A. The key cuts  86  may be made by a key cutting or key duplicating machine (the terms being used interchangeably throughout), described below with reference to  FIGS. 66-76 . 
     In the illustrated embodiment, the resilient clasp  42  (may be identical to that of  FIGS. 3 and 4 ) affixes the upper portions of the two half-shells to one another; no chassis is used. The lower portions of the two half-shells are affixed with a double resilient clasp, that is, two clasps  133  each formed with two outwardly extending tabs  131  at ends thereof. Clasps  133  are formed as one piece along with an axial connecting portion  135 . The double clasp serves to close the openings for the lower elements of the multi-element pin assembly. 
     With this cylinder lock made by MIM, material is left for clasps  133  to mount on, yet there is substantially uniform wall thickness throughout. Additionally, as seen in  FIG. 55 , there is substantially uniform wall thickness in the structure of the half-shell  138 A that forms the walls for the body (driver) pins  138  ( FIG. 54 ). Additionally, as seen in  FIG. 54 , there is substantially uniform wall thickness in the structure of the plug  136 A. There are substantially uniformly thick walls  136 B that separate the chambers for the plug pins  136 . When plug  136  is rotated in the body of the cylinder lock, the driver pins  138  do not fall into the places where material is missing (the chambers) because the driver pins  138  are aligned with the walls  136 B. Thus, the driver pins  138  and  138 A slide against walls  136 B as plug  136  rotates. Here again, there is reference abutting structure  82  on key  80 , which abuts against abuts against abutment  73  of plug  136 A. 
     Reference is now made to  FIGS. 56 and 57 , which illustrate a cylinder lock that employs plug locking elements which are in-line pins, e.g., plug pins  140  and driver pins  142 . 
     The cylinder lock includes a cylinder lock body made of two half-shells  143 A and  143 B, attached to a chassis  143 C. As with the other embodiments of the invention, the parts may be made by MIM. Chassis  143 C is illustrated with straight walls, but may be made with walls that curve at the area of the holes for the driver pins  142  for reducing weight and maintaining substantially uniform wall thickness. Chassis  143 C may have built-in rivets  143 D that are fastened in mounting holes  143 E of the half-shells  143 A and  143 B. The buck-tails of rivets  143 D (the part that is placed through holes  143 E) are bucked, upset, swaged or otherwise deformed after placement in holes  143 E to form the rivet connection. Rivets  143 D are positioned between holes  143 F for the driver pins  142  so that the rivets get support from the chassis walls and do not collapse the holes. 
     Reference is now made to  FIGS. 58 ,  59  and  60 , which illustrate a cylinder lock, which is an American mortise cylinder lock with a threaded cylinder lock body made of two half-shells  144  and  146  formed with threads on a portion thereof, attached to a chassis  148 . As with the other embodiments of the invention, the parts may be made by MIM with substantially uniform wall thickness. Chassis  148  may have built-in rivets  150  that are fastened in mounting holes  152  of the half-shells  144  and  146 , as described before for rivets  143 D of the previous embodiment. The plug  151  (preferably made of MIM with substantially uniform wall thickness) may operate a cam  154  fastened by mechanical fasteners (e.g., screws)  156 . 
     The half-shells  144  and  146  are preferably formed with winged extensions  144 A and  146 A, respectively, which are designed to accept the screw (not shown) that fixes the cylinder lock in the door, which is the standard way of installing the American mortise cylinder lock. In this embodiment, the winged extensions are dimensioned to extend to the diameter of the root of the threads of the threaded cylinder lock body, which provides support while screwing the cylinder lock in the door. The circular broken line in  FIG. 59  denotes the threaded hole into which the cylinder lock body is screwed. 
     Similarly, this embodiment can be modified accordingly to be a rim cylinder lock. For example, the winged extensions  144 A and  146 A may be respectively formed with threaded holes  144 B and  146 B for the rim cylinder lock installation. This feature saves on inventory costs—the same cylinder lock can be installed either as an American mortise cylinder lock or a rim cylinder lock, as desired. 
     Key Cutting Machine—Prior Art 
     Reference is now made to  FIGS. 61-65 , which illustrate a key cutting machine  160  of the prior art, such as the MUL-T-LOCK FULL SIZE or COMPACT II or KC-5 Key Cutting Machines, or the key cutting machines described in U.S. Pat. Nos. 6,602,030 and D441,379. 
     The key cutting machine  160  includes a key blank clamping assembly  162  for securing a key blank  164  for cutting key cuts thereon. As seen in  FIG. 63  (and also in  FIGS. 71 and 72 ), the key blank clamping assembly  162  includes a holding chuck  166  with a recess  168  formed thereon in which the key blank  164  is received. A clamp  170  clamps the key blank  164  to chuck  166 , so that a cutting tool  172  or  173  ( FIG. 63 ) can make key cuts in key blank  164 . Two cutting tools  172  and  173  are used to make key cuts for telescoping pins, as is known in the art. The key blank clamping assembly  162  can be moved from one cutting tool to another by means of a key blank translation assembly  174 , mounted along a rack-and-pinion mechanism  176 , for example. 
     If it is desired to duplicate the key cut code of a given key  178 , a key cut code reading device  180  is provided, shown in  FIG. 65 . Key cut code reading device  180  employs depth probes  181 , which are pins that probe the depths of the key cuts on the given key  178 . The depth probes  181  push on ends of levers  182 , whose other ends move a cutting template  183  into the proper cutting position for cutting tools  172  and  173 . The key blank translation assembly  174  is provided with a probe  177  ( FIG. 62 ) that follows the grooves on cutting template  183 . The key blank translation assembly  174  pivots about rack-and-pinion mechanism  176  as probe  177  goes in and out of the grooves on cutting template  183  so that the key cuts are cut in accordance with cutting template  183 . Thus, the key cut code reading device  180  follow or tracks the various depths or shapes of the key cuts of the given key  178 , and the key cut shapes are mimicked by the cutting tools  172  or  173 . 
     Key Cutting Machine of the Invention 
     Reference is now made to  FIGS. 66-70  and  73 - 78 , which illustrate a key cutting machine  200 , constructed and operative in accordance with an embodiment of the present invention. The key cutting machine  200  employs a different key blank clamping assembly  202  than the key blank clamping assembly of the prior art, which permits cutting key cuts in the key  80  of the present invention, while also permitting cutting key cuts of the prior art in prior art keys. The illustrated embodiment of the key cutting machine  200  is based on the cutting machine  160  of the prior art. However, it is emphasized that the invention is not limited to such a key cutting machine; rather the invention provides a method and module for transforming (i.e., modifying or upgrading) a prior art key cutting machine into a key cutting machine that is capable of cutting key cuts in a first key for a first cylinder lock (e.g., a prior art key in a prior art cylinder lock) and also capable of cutting key cuts in a second key for a second cylinder lock (e.g., the key  80  for the cylinder lock  10  of the present invention), wherein the key cuts for the first and second keys are cut at different angles with respect to a key-shaft-width axis, as is now explained. 
     As seen in  FIGS. 69 ,  73  and  74 , key blank clamping assembly  202  includes a holding chuck  204  with a first key holding surface  206  formed thereon on which the first (e.g., prior art) key blank is mountable, and a clamp  208  that clamps the first key blank on first key holding surface  206 . ( FIGS. 75 and 76  illustrate the prior art key blank  164  mounted on first key holding surface  206  and held by clamp  208 ). Holding chuck  204  also includes a second key holding surface  210  formed thereon on which the second key blank (e.g., key blank  80  of the invention) is mountable; the clamp  208  also clamps the second key blank on second key holding surface  210 . It is noted that the key blank can be inserted into the holding chuck  204  from either end of holding chuck  204 . 
     Clamp  208  is formed with one or more surfaces  209  to abut against the first key blank and one or more surfaces  212  to abut against the second key blank. It is seen that surfaces  209  and  212  may be on opposite faces of clamp  208  so that clamp  208  is turned upside down when switching between clamping the two different key blanks. 
     As seen in  FIG. 72 , (first) key  164  has a key-shaft-length axis  190  and a key-shaft-width axis  192 , perpendicular to key-shaft-length axis  190 . (The key-shaft-width axis  192  also runs through the key head, as shown). When the key cuts are made in key  164 , the key  164  is held so that key-shaft-width axis  192  is substantially vertical. 
     As seen in  FIG. 74 , (second) key  80  has a key-shaft-length axis  194  and a key-shaft-width axis  196 , perpendicular to key-shaft-length axis  194 . (The key-shaft-width axis  196  also runs through the key head  79 , as shown). When the key cuts are made in key  80 , the key  80  is held so that key-shaft-width axis  196  makes an angle A with the vertical. Thus, the key cuts for the first and second keys  164  and  80  are cut at different angles with respect to their respective key-shaft-width axes  192  and  196 . As mentioned above, since the key cuts are made at an angle, key copying is difficult because it is difficult to identify the key cuts by mere visual inspection. 
       FIG. 69  illustrates that the cutting tools  172  and  173  can also be used to cut the key cuts on key  80  of the present invention in key cutting machine  200 . As mentioned above, the shallowest possible key cut is definitely not flush with the surface of the key shaft and this depth is not easily discernible as the shallowest possible cut, making key copying difficult. 
     Reference is now made to  FIG. 70 . It is clearly seen that if key  80  were mounted on key cut code reading device  180  of the prior art, no duplication of key  80  is possible. This is because it is impossible for the key cut code reading device  180  of the prior art to read the key cutting code of key  80  of the present invention; device  180  has no provision for sensing these key cuts. Thus, duplication of key  180  of the present invention is restricted to the key cutting machine  200  of the present invention. The key cutting code of the present invention can be recorded on a recording medium, such as but not limited to, an electronic chip or card. 
     It is also appreciated that various features of the invention which are, for clarity, described in the contexts of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

Summary:
An article including a key comprising a key head that slides along a key shaft, said key head being affixable to said key shaft with a fastener.