How to Make a Bump Key

Co-authored by wikiHow Staff

Last Updated: June 29, 2021

A bump key is a lock-picking tool used to override many locks almost instantly. So, if your whole house has Evva locks, an Evva bump key could open every door. You can make one from a blank key, as long as you have the real key or lock as a guide. Bump keys are usually associated with lockpicking and burglary, but this how-to is strictly for legal purposes. Only open doors legally, and store your bump key in a safe place.

Part 1

Part 1 of 3:

Measuring and Shaping the Key

1
Purchase a blank key that matches the model of the lock you're picking. If you're trying to make a bump key for a Kwikset lock, you'll need a blank Kwikset key. ^{[1]
X
Research source}To make a bump lock, you'll need the key from the correct manufacturer as well as a working copy of the legitimate key.
- There are some people making bump keys without original keys as guides. To do so, you need an electronic caliper capable of measuring the distance between pins in the lock -- a complicated maneuver reserved usually for burglars without access to an original.^{[2]
  X
  Research source}
2
Review the basic vocabulary of keys before moving forward, especially if you are new to lock-picking. This how-to will use certain terms and phrases to refer to parts of the key. Knowing the simple terms will help you make a more effective key.
- Length: the length of the key from its tip to the end; the longest measurement of the key.
- Groove: a dip or indentation in the serrated edge of the key. Each groove is next to at least one peak.
- Peak: a tooth in the serrated edge of the knife. Peaks can be steep or flat, but jut outwards from the body of the key. Each peak is next to at least one groove.
- Maximum depth: the length of the deepest groove on the key. The deepest groove should never cross the track.
- Track: the narrow indentation along the key's length. Different keys have differently sized tracks. The track falls roughly in the middle of the key length-wise.
- Shoulder: when the key is inserted, the shoulder sits at the top and right outside the lock's entrance. The shoulder stops the key from being inserted too far into the lock.
Advertisement
3
Use a fine permanent marker to trace your real key onto the blank one. You need to know where each groove is along the length of the key, as well as the maximum depth that any groove has on the key. Lay your real key over your blank key. The only difference between the two is that the real key is serrated where the blank key, your bump key, is not. You only have to trace that serrated edge. ^{[3]
X
Research source}^{[4]
X
Research source}
- The maximum depth should never cross the track, which is the indent going through the length of the key.
4
Stick the blank key in a bench vice. Place the key so that the track and bottom are in the vice and the top sticks out. You will need to file the key into the shape you've outlined. You can set the original key aside.
- If you do not have a bench vice, find another way to hold your key securely while filing it down. You must be able to file down to an accurate depth, so having it somewhere it can't move is crucial.
5
Use your file to craft the bump key into a rough approximation of the original. Use the file, keeping the peaks in place. Your biggest goal is to never go lower than the maximum depth of the original. Just get the key into the rough shape of the original so you can fine-tune it into a bump key.

Part 2

Part 2 of 3:

Crafting the Key

1
Use a metal, triangular or taper file to grind the grooves into the bump key. The biggest thing to focus on is the depth of each groove. You never want to go past the tread running along the bottom of the key, and you never want to go deeper than the maximum depth of the original key.
- Do not worry about the sharp peaks between grooves for now -- they come next.
- You should have the same number of grooves as real the key.
2
File all the steep peaks down so they are only 4-5mm above the grooves. The peaks of your blank key are probably too high and might cause your key to get stuck in the lock. File down the peaks so that they are a few millimeters high. The right height is one that triggers your lock but doesn't get stuck; you may have to experiment and practice to find the right height.^{[5]
X
Research source}
- Your peaks should be of equal height to one another.
- The peaks just need to be high enough to catch in the lock.
3
Use your file to clean up the key so that all the grooves and peaks are at matching heights. Your final bump key should look like a saw with an evenly serrated, jagged edge. The little, toothy peaks, shouldn't be too steep, and the grooves should be evenly spaced right where the grooves on the original key are located. It is okay if the grooves are flat-bottomed.
4
Find the shoulder of the key. Insert your bump key into its respective lock, noting where the key stops it from going any further in. This is the shoulder, which exists between the grooves/peaks, and where your fingers grasp the key in order to use it. The shoulder exists to stop the entry of a key into a door at exactly the right location so that the grooves and peaks align with the lock.^{[6]
X
Research source}
5
File the shoulder down into a flat line. The shoulder controls how far the key goes into the lock, but you don't want the shoulder there. Using a bump key, you want to be able to control how far the key is going into the lock to jiggle the lock open. Getting rid of the shoulder allows you to position the key as you want while tapping it in. Use your file to wear the shoulder down to the height of your peaks, at least. ^{[7]
X
Research source}
6
File down the tip of the key. This is an optional step, but can help you fit the key in.The tip is the part of the key that inserts into the lock first. If you are having trouble fitting and jiggling the key into the lock, try filing down the tip of the key by 1/4 to 1/2 of a millimeter.
- You will need to fit small rubber spacers on this area, allowing you to "bump" the key against the lock so it recoils back a bit at you.
- This is called the “minimal movement” method. ^{[8]
  X
  Research source}^{[9]
  X
  Research source}

Part 3

Part 3 of 3:

Testing Your Bump Key (optional)

1
Place your bump key in the lock to test the required length. See where the shoulder used to be? Using your permanent marker, draw a dot or line where the key emerges from the lock. This mark should be right where your bump key's shoulder used to be.^{[10]
X
Research source}
2
Place rubber rings on the key where you made you marks. Slide them onto the key and position them where your key's shoulder used to be, starting at that mark you drew. To use a bump key, you want bouncing rubber where a real key has a metal shoulder. This way, the key will bounce back out a little every time to hit it into the lock. A good bump key will jiggle around in the lock fluidly until it properly aligns with the lock, and will not get stuck.^{[11]
X
Research source}
- If you do not have rubber rings, you can still test your bump key. You will have to reset the key in the lock after every time you hit it, though. This is called the “pull-back” method. ^{[12]
  X
  Research source}^{[13]
  X
  Research source}
- Any little rubber ring will do. You could use gaskets from the plumbing section of a hardware store, farm equipment, and hosing.
3
Place your bump key into the lock. If you push on your bump key and hear a click, then move on to the next step. If you do not hear a click, jiggle your key or consider filing half a millimeter off from the tip of the key.
- If you have rubber rings, your key should bounce back to its original position in the lock every time you push in and let go. ^{[14]
  X
  Research source}
- Without rubber rings, you must pull your key back out one notch after pushing it in once.^{[15]
  X
  Research source}
4
Turn the key slightly clockwise. Using one hand, apply light rotational pressure. It should be as if you were trying to turn the key to unlock the door. ^{[16]
X
Research source}
5
Hit the key into the lock lightly to "bump" it open. Hold a small hammer, the back of a screwdriver, or another mallet-like object in the hand not holding the key. Hit the key straight in the direction of the lock, bumping it several times while still rotating the key slightly. This will probably take a number of tries. Jiggle the key if needed.
- With rubber rings, you can hit many times in quick succession.^{[17]
  X
  Research source}
- Without rubber rings, you must pull your key back out one notch after pushing it in. This can get tedious, but it is not impossible.^{[18]
  X
  Research source}
6
Open your lock and remove your bump key. Keep it in a safe place and use it only for legal purposes. Note, however, that improperly made or used bump keys can permanently damage locks. Only use your bump key when you are absolutely sure you need it, as it can cause more headaches than it is worth if you aren't careful.
- The actual "bumping," or knowing how to turn the key and how hard to hit it, will take some practice. Each lock is slightly different, but you'll learn to get the feel for it with some practice.

Community Q&A

Question

What if I don't have access to the original key, but have used keys that fit in the lock but won't unlock it?

Community Answer

Go to a car dealer and show your license and registration. There is a way they can make your key.
Question

My original keys wont work after making the copy keys. But the copy keys work fine. How is this possible?

Community Answer

More than likely your original keys and lock (which we can consider as just the different size brass (usually) pins in the tumbler) these surfaces have worn down slightly over time. So, when you copied your original keys (depending on how the blank keys are cut, it could be a little different from the original). Now where the peaks and grooves of your original keys are worn down some, the peaks and grooves on your new keys are not worn down, and will have sharp edges if their not smoothed over some. Anyway, what likely happened is your new keys with their sharp edges/taller peaks, etc., cut into or wore down the tumblers in the lock after a few uses, and now your old "worn down" keys no longer work.

Warnings

Breaking and entering is illegal. This information is meant for educational purposes only.

⧼thumbs_response⧽
Helpful 0 Not Helpful 0
It is possible to break and/or wreck a lock while bumping. Be careful and be gentle with the locks.^{[21]
X
Research source}

⧼thumbs_response⧽
Helpful 1 Not Helpful 0