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The Bump Key Guide

Posted by Taylor Banks on June 20, 2012 (24 Comments)

Many visitors to ACE Hackware inquire about how to make a bump key. Of course we'd love to be able to sell you a  professional bump key set, but if you don't want to spend the money, making a bump key requires just a bit of knowledge, a few tools, some spare time and this bump key guide! 

If you haven't already, we would encourage you to first read our post, "How does a bump key work?" to give you a basic understanding of the function and use of a bump key.

Things You Need to Make a Bump Key

  • Blank keys for your specific lock
  • A depth and/or spacing guide for your lock manufacturer's keys, OR
  • A digital caliper to measure depth and spacing, plus a real cut key for your (or a similar) lock
  • A triangular or taper file or a key clipper
  • This bump key guide

From the manufacturer's depth and spacing guide (or from your own measurements using a cut key for the manufacturer's lock you aim to bump), you'll need to establish at least the following two measurements to make effective bump keys:

  • Key shoulder to first cut
  • Distance between key cut centers

How to Make a Bump Key

Using these values, you'll make your first cut using the first value (key shoulder to first cut), then each subsequent cut will be spaced at equal intervals using the second value (distance between centers). As a general rule, you cut to the indented line on the blank key. However, for greater accuracy and improved efficacy of your home-made bump key, you'll probably also want to determine the cut depth, which is a precise measurement from the bottom of a cut to the bottom of the key (this information should also be provided in your lock manufacturer's depth and spacing guide). If you don't have an accurate cut depth, you can generally cut to the indented line (never below!) and your key will probably work in most locks.

It is very important that you make sure that the valleys in your key do not go below the indented line on the key, and also that the angle of your cuts are shallow enough to allow smooth insertion and removal of your bump key from your target lock. If the valleys are too deep, your bump key will probably not work. If your valleys are too steep, you may damage the lock or you may not be able to remove the key from the lock once you've bumped it! Our professional bump keys are cut according to the manufacturer's specified cut depth with gradual valleys and gentle peaks. 

Finally, once you've created all of the necessary peaks and valleys in your new bump key, you'll want to file a small bit off the tip and shoulder of the key (generally <= 1/2mm will suffice).

Bump Key Videos

The instructions in this bump key guide will get you started, but if you want to know how to make a bump key better, you might also want to check out the following resources on bumping theory and the proper use of bump keys:

Note: Breaking and entering is illegal. This information in this bump key guide is meant for educational purposes and lawful use only.

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