Space & Depth Keys: What They Are, How They Work & When Locksmiths Use Them

When a locksmith needs to make a key without having the original, getting the cuts right matters; guessing can waste a key blank and still leave you with a key that doesn't work.

This is where space and depth keys come in.

A space and depth key set allows a locksmith to cut a key from a bitting code using the pinning information, without needing a code machine. That's the main job these sets do: they let you code-cut a key by hand, on a standard key duplicator, using nothing but the correct set of reference keys.

In this guide, we'll explain what space and depth mean, how these keys are actually used to cut a key, what the numbers mean, and how to choose the right set.

What Does "Space" Mean on a Key?

Space refers to the position of each cut on a key.

Think of a key as having several spots where cuts can be made. Each spot lines up with a pin inside the lock. If a cut is made in the wrong position, the wrong pin gets lifted, and the key won't work properly.

For example, a Kwikset KW1 key has five cut positions, while a Schlage SC4 key has six.

The exact spacing depends on the key type. Locksmiths can check the correct spacing using a code book, key machine software, or a space and depth key set.

Space = where the cut goes.

What Does "Depth" Mean on a Key?

Depth tells you how deep each cut needs to be.

Each cut depth corresponds to a specific pin, the bottom pin, that sits in that chamber of the lock. The cut has to be made to a precise depth so that pin can sit correctly in it. When the key is inserted, a correctly cut key lets every bottom pin drop down far enough to clear the shear line, which is what allows the cylinder to turn.

A shallow cut doesn't let the pin drop as far. A deeper cut lets it drop further. If even one cut is too shallow or too deep, the matching pin won't reach the shear line correctly, and the key won't turn.

Different key types use different depth numbers. For example, Kwikset KW1 uses depths from 1 to 7, while Schlage SC1 uses depths from 0 to 9.

Depth = how deep the cut goes, so the right pin can reach the shear line.

Together, the spaces and depths make up the key's complete bitting, its full cut pattern.

How Do Locksmiths Use Space & Depth Keys?

A space and depth key set is a stack of reference keys, one for each depth number in that keyway's range. Each reference key is cut to that one depth across every space on the blade.

Their main purpose is simple: they let a locksmith code cut a key by hand on a standard key duplicator, without needing a dedicated code machine. If a locksmith already has a code machine, they generally won't need a space and depth set for this job, since the code machine does the same work automatically. A space and depth set is most valuable when a code machine isn't available, or when a locksmith wants a manual way to originate keys from a code.

How Do Locksmiths Cut a Key From a Code Using Space & Depth Keys?

Cutting a key by code means making a new key using a bitting code instead of copying an existing key. The code is a string of numbers, and each number is the depth for one space on the key.

Here's how it actually works on a key duplicator, using an example code of 3-1-7-4-2:

1. Get the Key Code

The locksmith first needs the correct code. It may come from a code book, a manufacturer's records, or from decoding the lock itself.

2. Cut the Shallowest Depth First

Place a matching key blank in the cutting jaw of the duplicator. Insert the reference key for the shallowest depth in the code, in this example, the #1 key, into the tracing jaw.

Since #1 is the shallowest depth, it can safely be cut across all five spaces on the blank at once.

3. Move to the Next Depth

Swap the #1 reference key out for the #2 reference key. Using the same blank still sitting in the cutting jaw, cut only the space (or spaces) in the code that call for a #2 depth. In our example code, that's just the second space.

4. Repeat Through Each Depth

Continue this process, working from shallowest to deepest, swapping in each reference key and cutting only the spaces in the code that match that depth. By the time you've worked through depth #7 (the deepest depth in the KW1 range, for example), every space on the blank has been cut to its correct depth, and the full code, 3-1-7-4-2, is complete.

5. Test the Key

Once every space has been cut, test the finished key in the lock to confirm it turns smoothly.

What Do the Numbers on Space & Depth Keys Mean?

Each reference key in a space and depth set is stamped with a number, and that number is the depth cut into that key across every space on its blade. For example, a Schlage SC1 set includes individual reference keys numbered 0 through 9, each one cut to that exact depth. A locksmith works through these, shallowest to deepest, to build a new key one depth at a time, as shown above.

Some key systems also have rules about how much the depth can change between two cuts next to each other. This is known as the Maximum Adjacent Cut Specification (MACS), and it exists to keep the key blade from being cut too thin at any single point. You don't need to calculate MACS by hand to use a space and depth set correctly, since the set itself is built to the manufacturer's specifications, but it's worth knowing the term if you come across it.

Automotive space and depth keys work on the same basic principle, but they're built for vehicle key systems, which can vary quite a bit between manufacturers and models.

How to Choose the Right Space & Depth Key Set

Choosing the right set starts with identifying the keyway you're working with.

Here are three things to check:

1. Check the Keyway

The keyway is the exact shape of the slot inside the lock cylinder that determines which key blanks will fit into it. Every key blank is milled to match a specific keyway, so it fits and turns correctly in the matching lock.

A Kwikset KW1 set will not work on a lock built for a Schlage SC4 keyway. Always confirm the set matches the keyway you're working on.

2. Check the Number of Spaces

Different keyways have a different number of cut positions. Make sure the space and depth set you choose covers the same number of spaces as the key you're cutting.

3. Check the Depth Range

Make sure the set covers the full depth range for that keyway. This matters most with automotive and other specialized systems, where depth ranges can vary quite a bit between models.

For common residential and commercial locks, locksmiths most often reach for Kwikset, Schlage, and Master Lock sets. If you also work on vehicles, it's worth stocking automotive space and depth sets built for the specific systems you service.

A Simple Example of Using a Space & Depth Key Set

Say a property manager has a storage unit lock with no working key, and the lock uses a Kwikset KW1 keyway. A locksmith with a KW1 Space & Depth Key Set but no code machine on hand could originate a working key like this:

1. Get the bitting code for the lock, for example, 4-2-6-1-3.

2. Place a KW1 key blank in the cutting jaw of the duplicator.

3. Insert the #1 depth key (the shallowest depth in the code) into the tracing jaw and cut every space that calls for a #1 in the code.

4. Swap in the #2 depth key and cut only the spaces in the code that call for a #2, without removing the blank from the cutting jaw.

5. Continue through each depth in the code, shallowest to deepest, cutting only the matching spaces each time.

6. Once every space has been cut, test the finished key in the lock to confirm it turns smoothly.

This is the real advantage of a space and depth set: it lets a locksmith originate a working key from nothing but a code and a keyway match, entirely by hand, with no code machine required.

Featured Space & Depth Key Sets

CLK Supplies offers space and depth key sets for many common keyways and lock systems. A few popular options:

• KW1 Space & Depth Keys — For the Kwikset KW1 keyway, 5 spaces, depths 1-7.

• SC1 Space & Depth Keys — For the Schlage SC1 keyway, 5 spaces, depths 0-9.

• M1 Space & Depth Keys — For Master Lock M1 key systems and padlocks.

• SC4 Space & Depth Keys — For the six-space Schlage SC4 commercial keyway.

• Best BE2 Space & Depth Keys — For Best, Falcon, and Arrow interchangeable core systems used in commercial access control.

For more options, including sets for various automotive key systems, browse the complete Depth & Space Keys collection.

Other Tools Locksmiths May Need

Space and depth keys are only one part of a locksmith's toolkit. Depending on the job, a locksmith may also need uncut key blanks, a key duplicator or code machine, replacement lock pins, and a pinning kit for rekeying jobs. For automotive work, automotive picks and decoders are also worth having on hand.

Having the right tools for the keyway and the job makes key cutting and lock work much easier.

Conclusion

A space and depth key set allows a locksmith to cut a key from code, using the key's pinning information, without needing a code machine. That's the core idea to take away: space tells you where each cut goes, depth tells you how deep it needs to be so the right pin reaches the shear line, and a space and depth set lets you build that whole cut pattern by hand, one depth at a time.

Whether you work with Kwikset, Schlage, Master Lock, or automotive key systems, choosing a space and depth set that matches the keyway is what makes this method work. With the right set on your bench, you can originate a working key from a code alone, no code machine, and no original key required.