Originally made as portable convenience locks, padlocks are known for their cheap, simplistic and relatively secure design. Their construction is made up of a body, shackle and locking mechanism, with the shackle typically assuming a "U" shape to be easily linked to things like fences and chains.
Most padlock shackles use a swinging mechanism (older ones) or a sliding mechanism (newer), where the shackles slides out of the body when unlocked. This is a pretty typical design:
In this Null Byte, we are going to make a DIY shim, which is a tool that can open most padlocks without need of a key.
- 1 thin aluminum can
- Precision shears, or something similar to cut the can with
- Padlock (the cheaper, the more likely this will work)
- Aluminum is sharp. Be careful not to cut yourself with the can or cutting tool.
When it comes to padlocks, there's two basic kinds—integrated or modular. Integrated locks use tumblers to release the shackle, whereas modular locks are a little more complicated.
Integrated locks use either rotating disks or lever tumblers. Padlocks that employ this mechanism are slightly more secure in design, since they do not allow disassembly. When using the correct key, the bolt enters the tumblers and unlocks the device. Typically, these are your older style locks, and require you to use the key to not only unlock it, but lock it as well.
Modular locks do not use lever tumblers like integrated ones. Instead, they use pin, wafer or disk tumblers. When the correct key is inserted, a plug inside of the cylinder turns letting the so-called "locking dog" mechanism open the shackle. These are the padlocks you're probably used to now—the ones that can be locked without the key.
Step 1 Cut the Can
- Use your cutting tool and remove the top and bottom of the can. Then cut down the middle of the cylinder shape to create a thin sheet of aluminum.
- When you have the sheet, cut a shim out of the can by following the template below.
Step 2 Shim the Padlock
- Lock the padlock.
- Roll the shim around the "U" of the padlock, on the inside of the prong with the notch for the locking mechanism.
- Slide down for results.
This can even work for a lot of bike locks, so when investing in a lock for something precious, rethink which ones that you use. A good one with a tight build would be impervious to this trick.
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