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

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 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 M1 cylinder is a pin-tumbler lock with 4 pin stacks. It does NOT contain any security pins unless otherwise modified.

The No. 1 padlock uses the M1 key blank, but also can be made with a slightly different key profile. This change in profile helps to stop people from making copies of keys they shouldn't have.

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.

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

• 

  A cutaway No. 1 padlock and cylinder.

See also

• Padlock
• Pin-tumbler
• Master Lock