Lock Picking and Impressioning

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Picking open and impressioning locks quickly are fundamental abilities that every locksmith should have. This section gives all the information one needs to begin picking and impressioning all types of locks-including high-security models.

Picking Pin Tumbler Locks

With practice you should be able to pick open most standard pin tumbler locks within a few minutes-unless there's a problem with the lock. In theory, any mechanical lock that is operated with a key can be picked. Tools and techniques can be fashioned to simulate the action of any key.

The secret to picking locks fast is to focus on what you're doing and to visualize what's happening in the lock while you're picking it. If you know how pin tumbler locks work, then it's easy to understand the theory behind picking them. If you're not sure how they work, read Section. 7. ill. .1 shows an exploded view of a pin tumbler lock.

Why Pin Tumbler Locks Can Be Picked

The slight spaces and misalignments within a cylinder allow it to be picked.

When locks are manufactured, there has to be room in each of the lower and upper pin chambers for the pins to move back and forth freely. The lower pin chambers are those holes along the length of the plug that hold the bottom pins. The upper pin chambers are those corresponding holes inside the cylinder housing that hold the upper pins. To create a locked condition, one or more of the upper pins must fall into the lower pin chambers, or one or more lower pins must be raised partially into the upper pin chambers. When a pin tumbler is lodged between an upper and lower pin chamber, the plug can't be turned. In other words, it's locked.

ill. .1 In a pin tumbler cylinder there are many parts that all need to move freely; that freedom of movement makes a lock-pickable.

Springs Top pins; Bottom pins; Plug; Lower pin chambers

Cylinder housing

ill. .2 The right key lifts all the pin sets to the shear line, allowing the plug to turn. Side view Front view Cylinder in unlocked position Plug turning Top pin Lower pin chambers Shear line

Upper pin chambers

ill. .3 When the bottom and top pins meet at the shear line, the plug can be turned. Shear line Spring Top Pin Key


ill. .4 Top view of a plug showing lower pin tumbler chamber. Lock pick

ill. .5 To pick a lock, lift one pin set at a time while applying torque or turning pressure with a torque wrench. Torque wrench

Pin chamber holes aren't perfectly aligned, but there has to be enough room in each of the pin chamber holes for the pins to move in and out easily.

Likewise, there has to be space between the plug and cylinder housing to allow the plug to be turned to the locked and unlocked positions. (When you're turning the lock with a key, you're turning the plug.) ill. .2 shows the plug in an unlocked position. This is when the bottom and top pins meet at the shear line. Lockpicking takes advantage of the necessary spaces and slight mis alignments in a lock.

In the locked position, one or more pins are lodged between the upper and lower pin chambers-preventing the plug from turning. The right key has cuts that are positioned to move all the pins to the shear line at once, which frees the plug to be turned. The shear line is the space between the plug and cylinder housing. If all the pins are at the shear line, the plug is free to rotate ( ill. 3).

The upper and lower pin chambers aren't drilled in a perfectly straight line across the plug and cylinder. If you look at them closely, you'll see more of a zigzag pattern. ill. .4 shows the lower pin chambers aligned along the cylinder plug. In all but the most expensive locks, there is a lot of play for the pins within the cylinder. This is because manufacturing processes aren't perfect.

When you use a pick to lift a bottom pin, you're also lifting the corresponding top pin (or top pins in the case of a masterkeyed lock). As that pin stack is being lifted and you're applying varied pressure to your torque wrench ( ill. 5), the top of the bottom pin and the bottom of the top pin both reach the shear line at about the same time.

The top pin goes into its upper pin chamber and leans against the chamber wall. The bottom pin, depending on its length, either stops at the shear line or falls back into the plug. At this point the torque wrench is able to turn the plug slightly. When it turns, a small ledge is created on the plug for the top pin to sit on. This ledge prevents the top pin from falling back into the lower pin chamber when the pick is removed. The top pin will stay on the plug's ledge at the shear line as long as adequate pressure is being applied to the torque wrench. The shear line is the space between the upper and lower pin chambers.

The object of lock picking is to have the top and bottom pins meet at the shear line so that none of the pins are obstructing the plug from turning. If you're picking the pins in the proper order, as each top pin is lifted and set on the plug, the plug turns a little more, creating a bigger ledge. When all the top pins are on the ledge, all the bottom pins will be at or below the shear line, and the plug will be free to be rotated to the unlocked position by the torque wrench.


A common method of picking locks is the rake method, or raking. To rake a lock, insert a pick (usually a half-diamond or rake) into the keyway past the last set of pin tumblers, and then quickly move the pick in and out of the key way in a figure eight movement while varying tension on the torque wrench.

The scrubbing action of the pick causes the pins to jump up to (or above) the shear line, and the varying pressure on the torque wrench helps catch and bind the top pins above the shear line. Although raking is based primarily on luck¸ it sometimes works well. ill. .6 shows how a rake pick works.

Frequently, locksmiths will rake a lock first to bind a few top pins, and then they will pick the rest of the pins one at a time.

Using a Pick Gun

A pick gun can be a great aid in lock picking. To use one, insert its blade into the keyway below the last bottom pin. Hold the pick gun straight. Then insert a torque wrench into the keyway. When you squeeze the trigger of the pick gun, the blade slaps the bottom pins, which knock the top pins into the upper pin chambers. Squeeze the trigger several times. Immediately after each squeeze, vary the pressure on the torque wrench. You likely will capture one or more upper pins in their upper pin chambers and set them on the plug's ledge. Then you can pick each of the remaining pin sets one by one.

ill. .6 Raking a cylinder can pick one or more sets of pins at once.

ill. .7 Before picking a lock, use the back of a pick to make sure that each tumbler set drops freely.

ill. .8 Hold a pick like you would hold a pen.

ill. .9 Lift each pin set to the shear line, one set at a time.

Lock Picking Tips

Before attempting to pick a lock, make sure that it’s in good condition. Turn a half-diamond pick on its back, and try to raise all the pin stacks together.

Then slowly pull the pick out of the lock to see if all the pins drop or if one or more are frozen. If the pins don't all drop, you may need to lubricate the cylinder or remove foreign matter from it. (But don't lubricate the lock if you might want to impression it.) To give yourself maximum working space, use the narrowest pick available.

Hold the pick as you would hold a pencil-with the pick's tip pointing toward the pins. Don't use wrist action; your fingers work better in manipulating the pick in the lock.

With your other hand, place the small bent end of your torque wrench into the top or bottom of the keyway-whichever position gives you the most room to maneuver your pick properly. Make sure that the torque wrench doesn't touch any of the pins. Use your thumb or index finger of the hand that's holding the torque wrench to apply light pressure on the end of the torque wrench in the direction you want the plug to turn.

While using a pick, carefully lift the last set of pins to the shear line while applying slight pressure with the torque wrench. Make a mental note of how much resistance you encountered while lifting the pin stack. Release the torque wrench pressure, letting the pin stack drop back into place. Then move on to the next pin stack and do the same thing, keeping in mind which pin stack offered the most and least resistance. Repeat with each pin stack.

Then go to the pin stack that offered the most resistance. Lift the top of its bottom pin to the shear line while varying pressure on the torque wrench.

Apply enough pressure on the torque wrench to hold that picked top pin in place. Then gently move on to the next most resistant stack. Continue lifting each pin stack (from most resistant to least resistant) to the shear line. As you lift each pin stack into place, you will be creating a larger ledge for other top pins to rest on. When all the top pins are resting on the plug, the plug will be free to turn to the unlocked position. It's important to pick the pin stacks from most resistant to least resistant, because the less resistant stack creates a smaller ledge on the plug and will cause the already picked, more resistant stacks to fall off the ledge.

Picking warded locks

Warded locks are easy to pick. Sometimes you can even use a pair of wires- one for throwing the bolt and another for adjusting the lock mechanism to the proper height for bolt movement. Here, as with any other kind of lock picking, it’s a matter of practice on a variety of locks.

Warded padlocks have only one or two obstacles, thus simplifying your choice of pick. Some warded locks that have keyways with corrugated cross sections can be opened in no time at all by having several precut blanks avail able ( ill. 10). You can buy a set of warded padlock picks for a few dollars from a locksmith supply house. Smaller locks with correspondingly smaller keyways require that you get a second set of warded padlock picks and cut them down to size.

Warded bit-key locks are also easy to pick. (For more information on warded bit key locks.) Many can be unlocked by using an "L" shaped piece of coat-hanger wire about 6 ” long. The easiest way to unlock most warded bit-key locks is by buying a set of skeleton keys for a few dollars.

Picking lever tumbler locks

ill. .10 A few warded padlock picks can be used to open most warded padlocks.

ill. .11 A lever tumbler lock with the faceplate removed.

ill. .11 shows a lock with the faceplate removed, indicating the position of the tension tool in relation to the bolt. Holding the levers with the tension tool (as shown in the side view) enables you to manipulate the levers with the pick.

In learning to pick the lever lock, it’s best to start with a lock with only one lever in place. At first, work on the lock with the faceplate removed so that you can get an idea of how much pressure to apply to the bolt and how much movement is required of the pick to move the lever into position for the bolt to move through the lever gating.

As you progress to locks with several levers, keep the faceplate on. When you encounter a problem, remove the faceplate so that notice what you're doing wrong. Always remember to insert the tension tool first. Push it to the lowest point within the keyway so that the pick will have maximum working space.

As with the pin tumbler lock, one tumbler tends to take up most of the tension, so work on this one first. As you move this tumbler slowly up to the proper position for the bolt to pass through the gate, you will feel a slight slackening in tension from the bolt as it attempts to force its way into the gating. This tension will be transmitted to you through the tension tool. Stop at this point and do the same to the next lever with the greatest amount of tension. Continue until all the levers reach this point. Then, by shifting the tension tool against the bolt, the bolt will pass through the gate and open the lock.

There must be at least some pressure on the tension tool at all times. A lack of pressure will cause any levers in position to drop back into their original locations.

Picking disc tumbler locks

Standard disc tumbler locks (those using a single-bitted key) take the same picks as pin tumbler locks. Like the pin tumbler lock, a disc tumbler lock can be picked by bouncing the tumblers to the shear line. Usually a rake is the best tool for this job, but other picks can be used too.

To develop your proficiency, try opening a disc tumbler lock with the feeler pick, working on each tumbler individually. This helps you to learn which picks you are most comfortable with for different types of locks.

When working on double-bitted disc tumbler locks, the bounce method is best.

Insert the tension tool into the keyway, and apply a slight pressure to the core as you pull the pick out of the lock. These locks also can be opened with a standard pick set and tension tools, but it can take from 10 minutes to half an hour.

Picking High-Security Cylinders

All cylinders that use a key can be picked open. High-security cylinders often are harder to pick than a standard one because they have patented features and require special tools and techniques.

ASSA Cylinders

To pick an ASSA cylinder, you'll need a key blank that fits the cylinder. Cut off most of the length of the blade to give you room to pick the tumblers. Then use the blank as a turning tool while picking the cylinder.

Schlage Primus

To pick a Schlage Primus, you'll need a key blank that fits the cylinder (that has the same milling). Trim the length of the blade down to the milling to give you room to pick the tumblers. Then use the blank as a turning tool while picking the cylinder.

An alternative method for picking a Schlage Primus is to use a key blank that fits the cylinder and cut all the spaces 0.010 ” deeper than the lowest possible cut. Insert the key, pull it back out one notch, and use the key as a turning tool. While applying torque, smack the key into the lock hard. Repeat until the lock opens. This method works on the same principle as a pick gun.

Medeco Biaxial

To pick the Medeco Biaxial, use a rigid turning tool and pick the pins to the shear line. When the plug turns a couple of degrees, release a bit of pressure from the turning tool and gently rake each side of the keyway to rotate the pins to the sidebar. You also can try to rotate each pin one by one.

An alternative method for picking a Medeco Biaxial is to use a key blank that fits the cylinder, cut all the spaces 0.010 ” deeper than the lowest possible cut, and widen the cut flats about one-half their widths. Insert the key, pull it back out one notch, and use the key as a turning tool. While applying torque, smack the key into the lock hard. Repeat until the lock opens.

The Need for Practice

No amount of reading will make you good at picking locks. You need to practice often so that you develop the sense of feel. You need to learn how to feel the difference between a tumbler that has been picked and one that is in a locked position.

To practice lock picking, start with a cylinder that has only two pin stacks (or tumblers) in it. When you feel comfortable picking that, add another pin stack. Continue adding pin stacks or tumblers until you can at least pick a five-tumbler lock.

When you're practicing, don't rush. Take your time, and really focus on what you're doing. Always visualize the inside of the lock and try to picture what's happening while you're picking the lock. For best results, practice under realistic circumstances. Instead of sitting in a comfortable living room chair trying to pick a cylinder, practice on locks that are on a door or on a display mount.

With a lot of focused practice, you'll find yourself picking all kinds of locks faster than ever.

Impressioning Locks

From the outside, impressioning is inserting a key blank into a keyway in a way that leaves tumbler marks on the blank. You then file the marks, clean the blank, and reinsert the blank to make more marks. Then you file the new marks. You repeat the procedure until you no longer see marks and you have a working key. With practice, you should be able to impression most pin tumbler locks within 5 to 10 minutes.

Pin tumbler locks

To impression a pin tumbler lock, you need to choose the right key blank. It needs to fit smoothly in the lock. If the blank is too tight, you won't be able to rock it enough to mark it. The blank also needs to be long enough to lift all the pins. If you use a five-pin blank on a six-pin cylinder, you probably won't be able to impression the lock because the sixth pin won't mark the blank. To choose the right size blank, use a probe or pick to count the number of pin sets in the lock.

The material of the blank needs to be soft enough to be marked by the pins but not so soft as to break off while you're twisting or rocking the blank.

Nickel-silver blanks are too hard for impressioning because they don't mark well. Aluminum blanks are soft enough to mark well, but they break off too easily. Brass blanks work best. Nickel-plated brass blanks are also good for impressioning because the nickel plating can be filed off.

Filing the blank. New key blanks have a hardened glazed surface that hinders impressioning unless you prepare them. To prepare a key blank, shave the length of the blade along the side that comes in contact with the tumblers. Shave the blank at a 45º angle without going too deep into the blank ( ill. 12). You want the blank's bitting edge to be sharp (a knife edge) without reducing the width of the blank because some pins may require a No. 0 cut to reach the shear line. File forward only. Don't draw the file back across the blank.

Use a round or pippin file with a Swiss pattern No. 2, 3, or 4 cut. A courser file will shave the blank quicker but will leave rougher striations on the blank.

This will make the impression marks harder to see. A finer file will make the marks easy to see but will clog quickly while you're filing. This will make impressioning take a long time. You probably won't find impressioning files at a hardware store or home improvement center, but they're sold though lock smith supply houses.

Another popular way to prepare the blank is to turn the blank over and shave the other side of the blank along the length where the tumblers touch the blank. After shaving both sides of the bitting edge at 45º, you will have a double knife edge.

ill. .12 Shave the bitting edge of the blank at 45°.

Other Useful Equipment and Supplies

In addition to a file, you'll need a key-holding device, such as an impressioning tool or a 4- or 5-inch pair of locking pliers ( ill. 13). A magnifying glass can be helpful for seeing impression marks. A head-wearing type lets you see the marks and file at the same time. Head-wearing magnifying glasses are shown in ill. 14. Although they aren't essential, you can use depth and space charts and a caliper to file marks more precisely.

ill. .13 Use a pair of locking pliers to hold the blank while you're filing it.

ill. .14 Head-mounted magnifying glasses can help you to see impression marks.

Cylinder Key blank --Locking pliers

ill. .15 Using locking pliers or an impressioning tool to turn the blank in the cylinder.

Top pin Bottom pin Key blank ill. .16 When you turn the plug that has a prepared blank, the bottom pins will bind and leave an impression on the blank.

Popular Impressioning Technique

The pull method of impressioning is often used on pin tumbler locks. After preparing the blank, insert it fully in the keyway with locking pliers or an impressioning tool and turn clockwise ( ill. 15). This will bind the bottom pins against the chamber walls ( ill. 16). Maintain the turning pressure, and rock the blank up and down several times while slightly pulling the blank out, about 1/16 inch. The rocking and pulling will cause the pins to press into the blank, leaving small marks or "impressions." Then turn the blank counter clockwise, and rock the blank up and down several times while slightly pulling the blank out. (If the lock turns in only one direction, then twist the blank in that direction only.) Remove the blank from the keyway, and look for impression marks. You may see one mark or several marks. File down about one depth at each mark (ill. 17). You can use depth and space charts and a caliper to precisely file the blank.

Don't file where you don't see a mark. The marks will be subtle; they aren't dark imprints like a felt tip pin. They are a change in the texture of the key blank filing. When the light is properly reflected, the markings look like small, smooth spots. You may need to view the blank at different angles to see the marks.

ill. .17 Only file the marks that notice clearly.

Never file more than one key depth for the lock you're working on. If you don't have a caliper and depth and space charts, just file two or three strokes at a time. (File forward only.) It's better to file too little away than to file too much. Sometime dirt or debris may seem like a mark. If you're not sure if what you're seeing is an impression mark, use a clean cloth to wipe the blank.

After filing the marks, clean away excess metal on the bitting side of the blade by again filing it a little at a 45º angle. Just a couple of forward strokes on each prepared side will be enough. Don't decrease the width of the blade.

Alternative Impressioning Method

Another method of impressioning is called tapping. This is where you insert a prepared blank in the keyway and insert a steel rod in the bow. Use the rod for leverage to turn the bow clockwise; then, while maintaining the pressure, use a small hammer to tap the top and bottom of the bow several times. Then twist the bow counterclockwise, and while maintaining the pressure again, tap the top and bottom of the bow several times. The twisting is to bind the pins, and the tapping is to force the pins to mark the blank. File down at each mark you see. Clean the blank with one or two light strokes across the length of the blade. Repeat the procedure until you have a working key.

Problems with Impressioning

One common problem that happens during impressioning is that the blank cracks or breaks off near the bow. This is more likely to happen if you use aluminum blanks or locking pliers that are too large. If your brass blanks are breaking off, you're turning too hard. You don't need to turn very hard. It's the rocking that marks the blanks, not the turning.

If your blank cracks or breaks, duplicate it on a key machine or by hand.

Then use the new blank to finish impressioning the lock.

Anything that makes it harder for the pins to mark the blank will hinder your impressioning attempts. Problems can include: missing or worn tumbler springs, worn tumblers, a long pin next to a short one, extremely close tolerances within the lock, and oil, dirt, or debris in the cylinder.

There isn't much you can do about it if the lock is too old and worn. But if you have a hard time making marks, use a nonoil, wax-free spray cleaner for electronic parts. Shoot a couple of squirts into the keyway and let it dry. That should clean the lock.

Impressioning Practice

No amount of reading will make you skilled at impressioning because during impressioning you have to make a lot of judgment calls-which will get better only with experience. You have to judge how hard to twist and rock the blank, how hard to file, and how deep and how wide to make a cut based on the type of mark you see.

If you've never impressioned a lock, practice by using a lock with only two sets of pins. Prepare the blank to a knife point. Insert the blank into the key way and twist the key clockwise, and while maintaining the pressure, rock the blank up and down and pull it out slightly. Then twist the blank counter clockwise, and while maintaining the pressure, rock it up and down and pull it out slightly. Remove the blank from the lock, and observe the marks made by the pins. File at the strongest mark only. Cut just one mark at a time before cleaning the blank and reinserting it in the keyway to make new marks.

Repeat the turning, rocking, pulling, and filing procedure until you have a working key.

When you're able to impression a two-pin lock, add another pin stack, and practice impressioning it. Continue adding pins until you can quickly impression a five-pin tumbler cylinder.

Warded Bit-Key Locks

Impressioning a warded bit-key lock relies on the ability to decipher small marks made on a smoked key blank that has been inserted into a lock and turned.

Interpretation of the marks tells the locksmith what cuts to make, where to make them, and how deep they must be. The advantage of impressioning is that you need not disassemble a lock or remove it from a door to make a key.

The first cut allows that blank to enter the keyhole. Since you don’t have the original key, smoke the end edge of the blank, and insert it into the keyhole so that the edge comes into contact with the case ward. Scribe mark the top and bottom of the ward on the blank. Remove the key; the candle black that was removed indicates the depth of the cut, and the scribed marks show the position of the cut on the blank. Transfer the scribe marks to the near end of the bit, and draw lines connecting the two pairs of marks. Use a small piece of metal to make a depth gauge so that you won’t file too deeply. Mount the blank in the vise, and cut the ward slot. When you're finished, the key should pass the case ward.

Next, prepare the blank for impressioning the internal wards. Recall that the key must pass certain side wards. When the lock is assembled, how can you be sure exactly where to cut the key so that it will pass these wards? You can't. You will have to prepare the key blank using one of two methods. The first is to coat the key with a thin layer of wax. This is unprofessional and can harm the lock.

The wax may clog the mechanism, forcing you to disassemble and clean the mechanism at your expense- you can't charge a customer for your mistake. A more professional method is to smoke the key. The smoking must be thick enough to form a stable marking surface. If, e.g., the blank is thicker than it should be, enough blackening must be present to give true readings. A thin coat will speckle as you turn the key and send you on wild goose chases.

The technique for impressioning the key is as follows:

1. Insert the key into the lock and turn it with authority. Remove the key. You will notice one or more bright marks where the blackening has been removed. These marks indicate obstructions. File the appropriate cut for the key to pass.

2. Blacken, insert, turn, and remove the key. If a mark is present below the point you filed, the cut is too shallow. Carefully file it deeper. When the cut is deep enough, use emery paper to clean off the fine burrs left by the file.

3. Reinsert the key, and turn it again. It should pass the wards. If it tends to stick slightly, quickly and lightly pass over the cut with the warding file to alleviate the problem. Note: The cut should be square on all sides. Think of each ward cut as a miniature square, perfect and even on all sides.

4. Smoke the key, insert it, and turn it. The edges of the cuts should be shiny.

The brighter the spot, the greater is the pressure at that point. As the individual cuts are filed deeper, the bright spots grow dimmer. When this hap pens, you are close to the point where you should stop filing.

You must be more cautious each time you insert the key to test the depth of the cut. You are working "in the blind"; a small overcut means that the depth is permanently wrong on the blank, and you have to start over. This is the reason for making a few light but firm strokes as you near the completion of each cut. Take your time and make one perfect key instead of rushing the job and making many incorrectly cut keys.

The cuts on the key should be as deep and as wide as necessary but no more.

Overly large cuts interfere with the action of the lock and may force you to cut another blank.

Once the key is complete, it must be dressed out. Use emery paper to remove burrs before they break off and fall into the lock, and then polish the entire key with emery paper. For appearance, you also may give the key a light buffing on your wheel. It does you no good to give the customer a dirty and smudged key. Show pride in your work!

In practice, however, there isn't much reason to impression a warded lock.

For only a few dollars, you can buy a set of four to five skeleton keys that will open most bit-key locks or a set of warded padlock picks that will unlock most warded padlocks.

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Updated: Friday, February 21, 2020 9:07