What Are Space and Depth Keys?
Space and depth keys are a reference set of pre-cut keys used by locksmiths to cut a new key from a bitting code, without needing a code machine. Each key in the set represents one specific depth value, cut across every space on the blade. By working through these reference keys from the shallowest depth to the deepest, a locksmith can manually cut a key blank on a standard duplicator to match any bitting code for that keyway.
Space and depth keys are especially useful when a code machine isn't available, or when a locksmith wants a manual way to originate a key directly from a known bitting code.
How Do Space and Depth Keys Work?
Space and depth keys work by isolating one depth value at a time. Each reference key in the set is cut to a single depth, applied across every space on the blade, based on the manufacturer's bitting specifications for that keyway.
To cut a key from a code, a locksmith places a matching key blank in the cutting jaw of a duplicator and inserts the reference key for the shallowest depth in the code into the tracing jaw. That depth is cut across every space in the code that calls for it. The locksmith then swaps in the next-deepest reference key and cuts only the remaining spaces that require that depth, repeating this process from shallowest to deepest until every space on the blank has been cut to match the full bitting code.
Key Components of a Space and Depth Key Set
A typical space and depth key set includes:
- Depth keys – reference keys cut to each possible depth value for a given keyway, used to cut a blank one depth at a time
- Reference chart/manual – manufacturer bitting specifications showing valid depth values for a given keyway
- Labeled key ring or case – organizes keys by keyway and depth number for fast identification during use
- Compatible keyway blanks – sets are typically keyway-specific (e.g., Schlage SC1, Kwikset KW1), so multiple sets are needed to cover different lock brands
Because these sets are precision-cut references, keeping them organized and undamaged is essential for accurate results.
What Are the Common Uses of Space and Depth Keys?
Space and depth keys are used in several locksmith scenarios, including:
- Cutting a new key directly from a bitting code, without a code machine
- Originating a key when the original is lost but a code is available
- Training locksmiths in manual, code-based key cutting techniques
- Servicing keyways where a code machine isn't available or practical on the job
- Building keys by hand for property managers, storage facilities, and similar jobs where speed and low cost matter
They're most commonly used by locksmiths who don't have a code machine on hand, or who prefer a hands-on, manual method for cutting keys from a code.
Main Characteristics of Space and Depth Keys
Space and depth key sets share several defining traits:
- Keyway-specific, matched to a single lock brand and profile
- Made up of individual reference keys, one for each depth value in that keyway's range
- Based on manufacturer bitting charts for accurate depth values
- Used for manual, hand-cut key origination from a code, rather than automated code-machine cutting
- Require practice and familiarity with the specific keyway to use efficiently
These characteristics make space and depth keys a specialized, skill-based tool rather than a plug-and-play solution.
How to Use Space and Depth Keys
Using a space and depth key set to cut a key from a code generally follows this process:
- Identify the keyway of the lock and select the matching space and depth key set.
- Get the bitting code for the lock, either from a code book, manufacturer's records, or by decoding the lock.
- Place a matching key blank in the cutting jaw of a duplicator.
- Insert the reference key for the shallowest depth in the code into the tracing jaw, and cut every space in the code that calls for that depth.
- Swap in the next-deepest reference key and cut only the remaining spaces that call for that depth, without removing the blank from the cutting jaw.
- Repeat this process, working from shallowest to deepest, until every space on the blank has been cut.
- Test the finished key in the lock to confirm it turns smoothly.
This process takes practice, since working through several reference keys accurately on the same blank requires a steady hand and familiarity with the keyway. Many locksmiths first practice on spare blanks before cutting keys for customer property.
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