Lock Bumping: How secure is your home?

Posted By on November 28, 2006

Lock BumpingOne advantage of a “desultory” blog is that there are very few topics too far out to blog on. Last night I caught a ‘news teaser’ from local Cincinnati television station WXIX talking about “Lock Bumping” and have included the short segment at the bottom of this post. (or check it out on YouTube) Hmm, interesting … interesting enough to do a little more digging on the Internet and worthy of bring to the attention of my family and friends. I suspect that this lock ‘picking’ technique is a real eye opener for many homeowners? Most of us feel at least the locked door to our house is somewhat secure and that only thieves interested in ‘breaking in’ will gain access to our homes. Nope, according to what I’m learning, this ‘bumping’ technique developed in Denmark in the 1950’s can quickly crack about every consumer house lock being made.

Looking into this topic a little further, there’s plenty of information. From “Lock Bumping on Wikipedia,” to How-To PDF files to product selling websites, tovideo clips demonstrating it, its a pretty easy skill to learn. Almost any high school kid with a computer, a key blank that fits the particular brand of lock and a small hardware store file could quite easily learn how to open a locked home without leaving so much as a trace. Just imagine what a burglar doing this regularly must know?

Here’s how it works: A key fitted for a particular brand of lock is filed so that when it is inserted into the lock and tapped with a small mallet or suitable weighted striker, while turning the key will within seconds open the lock. It works because hitting the key forces it deeper into the lock, allowed by the removed shoulder and tip. (it was filed away) The bottom internal pins are forced up because of the elevations that were left standing between the groves. Each bottom pin transmits this upward impulse to the pin sitting immediately on top of it. The top pins fly upwards, while the bottom pins remain down. As the top pins separate from the bottom pins, the cylinder can be turned and the lock opened.

What options do homeowners have: We can purchase more precisely manufactured locks with tolerances that make bumping more difficult. (industrial grade lock sets tend to have higher tolerances) Also, some lock sets use magnetic pins, security pins or other pick-resistant construction — these generally make bumping the lock very difficult if not impossible. Locksmiths recommend using a professional grade lock that have registered key profiles — ones that aren’t readily available to the public but only to professional locksmiths. They also recommend the higher grade locksets carried and serviced by locksmiths such as the Medeco or Schlage Primus products. Avoid the majority of hardware and retail store brands.

Another avenue is to invest in a home security system monitored by an alarm company. Besides the “protected by” sign, lights and siren, and phone call to authorities, you might even get a discount on your homeowners insurance policy. Its possible that thieves might even pass over your home in search of easier targets if they know your home is monitored? If you are concerned about your home and its locks, perhaps getting to know a bonded and reliable local locksmith might be a small price to pay.


Desultory - des-uhl-tawr-ee, -tohr-ee

  1. lacking in consistency, constancy, or visible order, disconnected; fitful: desultory conversation.
  2. digressing from or unconnected with the main subject; random: a desultory remark.
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