Master Lock No 1

Master Lock No. 1

Master Lock No. 1
Name	Master Lock No. 1
Manufacturer	Master Lock
Lock Type	Padlock, Cylinder
Lock Design	Pin-tumbler
Specifications
# of Components	4
Component Type	Pin-tumbler

The No. 1 is a pin-tumbler padlock made by Master Lock. The No. 1 uses a laminated padlock body with an internal key-in-knob-style cylinder. The inner cylinder uses four pin stacks and does not use any security pins.

The No. 1 is one of the most common low security padlocks used in the United States.

Principles of operation

The No. 1 cylinder is a pin-tumbler lock with four pin stacks and no security pins. The cylinder typically uses the M1 key profile but may use other profiles, as well. The standard No. 1 can be opened in both directions but the "commercial" series body restricts opening to clockwise rotation. The No. 1 is not a key retaining padlock.

Disassembly instructions

The No. 1 cannot be disassembled non-destructively. To disassemble it the rivets that hold the laminated body together must be removed and each layer removed individually. The inner cylinder itself can be disassembled in the same manner as a traditional pin-tumbler lock:

1. Remove the cam or C-clip.
2. Insert the key and turn the plug 45-90 degrees.
3. Withdraw the plug from the cylinder. (A plug follower is recommended)

OR

1. Remove the chamber casings and take out each pin-stack individually
2. Remove the cam or C-clip.
3. Withdraw the plug from the cylinder.

Notes

• The No. 1 cylinder requires a small diameter plug follower.
• The No. 1 plug is retained by a crimp, rather than a C-clip or cam. Above are the generic pin-tumbler disassembly instructions.

Vulnerabilities

The No. 1 is vulnerable to a wide range of attacks. The reduced pin tumbler count and poor manufacturing tolerances makes it an easy lock to pick. It's commonly given to locksport beginners as a "confidence lock"; a lock that is easy to open and inspires you to continue picking. The No. 1 may be vulnerable to one or more of the following:

• Lockpicking
• Key bumping
• Impressioning
• Decoding
• Bypass
• Destructive entry

Gallery

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  A cutaway No. 1 padlock and cylinder.

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  Master Lock No. 1 insides

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  Master Lock No. 1 Pins

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  Master Lock No. 1 Actuator (1)

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  Master Lock No. 1 Actuator (2)

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  Master Lock No. 1 Actuator (3)

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  Master Lock No. 1 Actuator (4)

See also

• Master Lock
• Padlock
• Pin-tumbler