- Arrow Lock & Door Hardware
- Baldwin Hardware
- BEST Access Systems
- Cal-Royal Products, Inc.
- Corbin Russwin, Inc.
- Emtek Products, Inc.
- General Lock
- Hager Companies
- Kwikset Corporation
- Master Lock Company LLC
- Preso-Matic Keyless Locks, LLC
- SARGENT Manufacturer Company
- Segal Lock Company
- Unison Hardware, Inc. (INOX)
ASSA High Security Locks
- Catalog and Technical Manual
- ASSA TWIN 6000 – Technical Service Manual
BiLock North America, Inc.
- BiLock Exploded Illustration
Corbin Russwin, Inc.
- Access 3 – Technical Manual
Kaba Ilco Corporation
- Kaba Mechanical Lock Cylinders (Kaba GmbH)
- Peaks Global – Technical Manual
- Peaks Global and L10 – Catalog
- Peaks Preferred and Classic – Technical Manual
Medeco Security Locks
- Catalog (2018)
- ARX – Manual
- Medeco Original – Technical Service Manual
Mul-T-Lock USA, Inc.
- Mul-T-Lock – Service Manual
SARGENT Manufacturing Company
- Sargent/ASSA V-10 – Technical Service Manual
- Sargent Degree – Technical Manual
- Schlage Primus – Service Manual (2012)
- Schlage Primus – Service Manual (2014)
- KeyMark – Service Manual
In the Resources section, we have links to great write-ups on the Abloy Classic, Abloy Dislock/Exec, Abloy Protec, Abloy Special Products, ASSA Twin Systems, and Mul-T-Lock’s various platforms. We also have a comprehensive list of patented lock and key platforms which lists platform type, patent type, and patent expiration dates.
If you haven’t already, take a moment to stop by our Key Bitting Specifications page in the Tools section. For those new to locksmithing or for those that might not understand some of the abbreviations or information listed, I’m going to take a moment to cover each item by using one of the most popular keying systems in the United States: Schlage Classic.
Throughout this article I’m going to reference information as it’s organized in our key bitting specifications. Yes, we organize information in an arbitrary manner (one we think is the most conducive), but the information we include is the same information manufacturer’s use as well; that’s where we draw our information from, after all. Also, I’m not going to focus on items like key origination options or notes – that’s self-explanatory. Finally, I’m going to define terms using The LIST Council’s Professional Locksmith Dictionary. With that said, let’s cover the information left to right, top to bottom.
What’s in a Key Bitting Specification?
Not all manufacturers list the same amount of information in each of their key bitting specifications. Some manufacturers choose to share more information than others. At the very least, we’ve found that spacing and root depth information is listed by all manufacturers. Schlage, on the other hand, leaves nothing to guess work; they list just about every relevant detail necessary for generating or decoding keys and/or pins of their keying systems. Regardless of availability, all manufacturer’s key bitting specifications include the following information:
MACS, or maximum adjacent cut specification, is the maximum allowable difference between adjacent cut depths. MACS essentially tells you which cuts are allowed to be next to each other. If your MACS is 7, for example, a 2 cut can be right next to a 9 cut because when subtracting their difference, 9-2=7, it is at or below the MACS of 7. If the adjacent cuts were 1 and 9, however, their difference would be 8, which would violate MACS and therefore would not possible. In the Schlage Classic keying system, the MACS is 7.
Increment is the distance between different, successive depths. If you look at the Root Depths, or the dimension from the bottom of a cut on a key to the bottom of the blade, you’ll notice that the measurements of different, successive depths increase or decrease, depending on the order in which you read it, by .015″. This .015″ difference is the increment for Schlage Classic.
Progression is defined as a logical sequence of selecting possible key bittings, usually in numerical order from the key bitting array. That might not make sense in our context but allow me to explain. Progression relates to master keying and can be represented as either “Single Step” or “Two Step”. Differences between cuts in progressed keys can either be 1 increment (Single Step) or 2 increments (Two Step), depending on the size of the increment. Due to tolerances and the potential for key interchange and even cylinder failure, progression must match the manufacturer’s specifications. For all intents and purposes, if the increment size is less than .023″ then it is considered a two step progression, if it is more than .023″ then it is considered single step progression. Using Schlage Classic, which is a two step progression, we cannot have a difference between cuts of 1 increment in the same chamber of a master keyed cylinder or the aforementioned risk of key interchange and cylinder failure will exist. Therefore, we must have two step, or 2 increment, progression for Schlage Classic.
E.P.D., or effective plug diameter, is the dimension obtained by adding the root depth of a key cut to the length of its corresponding bottom pin which establishes a perfect shear line. E.P.D. will not necessarily be the same as the actual plug diameter.
Included Angle is a measurement from one sloping surface of a cut to the opposite surface, typically stated in degrees. If you look at the geometry of key cuts you’ll see that they look very much like a valley. Each side of the valley is what the definition refers to as a “sloping surface”. The measurement between each sloping surface is our included angle. For Schlage Classic the included angle is 100 degrees.
Root Cut, not to be confused with the cut root, refers to the measurement of the bottom of the individual cut itself. It is also sometime referred to as cut flat. Key cuts may have different cut root shapes, or the shape of the bottom of the key cut (either flat or radium or even a perfect “V”), but the bottom of the cut will always have a measurable distance. In our example, the measurement of the bottom a cut in Schlage’s Classic key bitting specification is .031″.
Spacing is can refer to two things. First, T.F.C., or To First Cut, refers to the distance between the shoulder or tip, depending on if it’s tip-to-bow or bow-to-tip, to the center of key’s first cut. B.C.C., or Between Cut Centers, is the distance between the centers of adjacent cuts. If you have a LAB Universal Pin Kit both values can be found in each manufacturer’s box. In each case, we have the full spacing information for all key bitting specifications. That includes the T.F.C. measurement, the B.C.C. measurement, and each respective available spacing measurement possible.
Finally, we include all pin segments available for a respective key bitting specification. In the case of Schlage Classic that includes bottom, master, and top pins. In other examples, such as Corbin X Class (System 70), we include bottom and master pins for both available plug diameters as well as interchangeable core top pins and build-up pins. Whatever is available for a respective key bitting specification we include, and with the manufacturer’s verbiage.
How do we use a Key Bitting Specification?
As we say on the Key Bitting Specification page, you’re only limited by your imagination with ways to utilize and “translate” the information from key bitting specifications. The following tasks can be completed, or greatly assisted, with an accurate key bitting specification:
- Key Generation
- Key Decoding
- Determining Keying Systems
- Determining Applicable Blanks
- Cylinder Pinning
- Cylinder Decoding
- Master Key and Master Key System Design
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Patent Number: 1,674,841 (Google Patents)
Filing Date: August 20, 1923
Issue Date: June 26, 1928
Inventor(s): Walter R. Schlage
I would personally consider the 19th century as the “golden era” of lock innovation and discovery. The first half of the century, or at least a large portion of it depending on who is defining it, was part of the Industrial Revolution. New manufacturing processes and factories allowed for innovation and inventions never before seen. Men like John Wilkinson and Henry Maudslay helped usher in a new wave of development in machining and tooling. Among the Wilkinson’s and Maudslay’s of the world were the Blake brothers of New Haven, Connecticut. On December 31, 1833, they received a patent for their “escutcheon latch” which was, for all intents and purposes, the forerunner of the modern cylindrical lock.
The “escutcheon latch” was a radical departure from the norm of the time: the mortise lock. Rather than a lock case operated by a key and/or auxiliary trim, the escutcheon latch contained a latch and knob trim that were much, much smaller and utilized a door prep that paled in comparison to it’s mortise counterparts. To quote lock historian Thomas F. Hennessey, “This type lock was almost one hundred years ahead of its time as it did not become popular in the lock industry until the 1930s.” While the “escutcheon latch” never caught up, other inventors sought to create their own version of what could compete with and perhaps even replace the mortise lock. Other early patents related to modern cylindrical and tubular locks included:
- 82,851 by Franklin and Frederick Babcock, 9/29/1868
- 158,811 by Elias Skinner, 1/19/1875
- 159,281 by Oscar Russ, 2/2/1875
- 166,856 by Gilbert Dickson, 8/17/1875
- 212,956 by Washington Ludlow, 3/4/1879
- 440,846 by Henry Hooper, 11/18/1890
- 637,497 by Herbert Burden & Samuel Lovatt, 11/21/1899
- 805,687 by Fred Vieweg, 11/28/1905
- 823,348 by John Montgomery, 6/12/1906
- 920,091 by Henry Simpson, 4/27/1909
- 943,898 by Henry Simpson, 12/21/1909
- 1,040,966 by Henry Voight, 10/8/1912
- 1,154,573 by William Kemble & Charles Underhill, 9/21/1915
- 1,207,123 by Clive Acker & Thomas Arsneau, 12/5/1916
- 1,393,021 by Louis Huffman, 10/11/1921
- 1,395,414 by Louis Huffman, 11/1/1921
In 1923, however, Walter Reinhold Schlage, a German who immigrated to the United States and created his own lock company, filed a patent for what we now call the cylindrical lock. Walter’s version utilized knob trim, and relied on a just two small holes in the door to install. This patent wasn’t the first or last Walter received for a version of a cylindrical lock, however. Others included:
- 1,456,041 5/22/1923
- 1,489,675 4/8/1924
- 1,579,457 4/6/1926
- 1,653,512 12/20/1927
- 1,653,513 12/20/1927
- 1,691,528 11/13/1928
- 1,691,529 11/13/1928
With his design, Walter was able to successfully challenge the mortise lock, the de facto standard for doors, exterior and interior, found in American residences. Schlage’s invention allowed doors to be fitted with a lock at a fraction of the time and cost of mortise locks. Furthermore, largely due to his companies’ existing manufacturing capabilities – which were able to manufacturer 20,000 locks a month by 1925, Walter was able to mass produce the lock. The lock became a hit and locks in America would never be the same. The cylindrical lock still remains the overwhelming standard in American residential construction. It also has a very large market share in commercial construction as well.
Over the course of his life, Walter Schlage was issued an astounding 250 patents related to locks. In 1946, Walter died but his companies continued to flourish. Schlage continued to expand and purchased other lock and door hardware companies, such as LCN. In 1974, Schlage was acquired by Ingersoll and Rand and in turn acquired new manufacturing facilities in New Zealand (1975) and Colorado (1976). Schlage would relocate it’s administrative offices to Colorado in 1997 while keeping it’s Technical Services and Customer Services divisions in San Francisco. In 2013, Schlage, along with 23 other global brands, were acquired by Allegion, where they still operate to this day.
We’ve just added a reference chart (direct link here) to the Library which contains function numbers, common names, and descriptions of the most popular ANSI/BHMA mortise, bored (cylindrical), interconnected, deadbolt, deadlatch, and deadlock functions. It’s laid out in a way that we think is streamlined for locksmiths who may have not fully committed these functions to memory.
If, for example, you wanted to decipher the function of a lock in hand OR you wanted to specify a function number based on the characteristics of the lock, you can quickly narrow it down by utilizing this sheet. This, we believe, is far more advantageous than the current method of reading multiple function descriptions via manufacturer’s literature.
The derived information should be compared to the manufacturer’s literature as final confirmation prior to ordering their specific lock.
Here are a few video tutorials related to the servicing and pinning small format interchangeable cores.
This first video allows you to create a pinning chart for small format interchangeable cores in literally seconds. Whether an A2, A3, or A4 system, you only need a piece of paper and a pencil or pen to get the job done. No software, websites, Excel spreadsheets, just basic math.
This next video is a pinning tutorial. In addition to basic pinning information I shared a few techniques and methods I use during the pinning process.
The final video covers tools commonly used to service and pin small format interchangeable cores. I give my opinion on the tools as well as demonstrate their usage.
This post will also be archived in the library.
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Patent Number: 1,561,771 (Google Patents)
Filing Date: March 18, 1922
Issue Date: November 17, 1925
Inventor(s): Frank E. Best
Frank Ellison Best was a high school custodian for a large high school in Washington state (incorrect, see update below). His key ring reportedly carried upwards of 100 keys, one for virtually each door. When a key was lost for one of these doors/locks, Frank was tasked with rekeying it. Frank was determined to create a better lock that allowed for a faster and more economical rekeying process. For 7 years, Frank tinkered with ideas. In 1922, he applied for patents for two of those ideas. The first (1,500,297), filed in February, secured a “figure 8” core into a cylinder housing by use of a screw.
The second (1,561,771), filed a month later in March, secured a similar “figure 8” core into a cylinder housing as well but rather than rely on a screw it used the core’s “extending shoulder”. This extending shoulder is what is commonly known as the “control lug” today. Furthermore, this extending shoulder could be retracted by use a special key, eventually known as a “control key”. This meant that a core could be removed and replaced in seconds with nothing more than a key. It’s not hard to imagine which core eventually caught on.
Frank would go on to form Frank E. Best, Inc., which became the patent holder for his core and other patents. Best would also create a separate company, Best Universal Lock Corporation, in 1925 to manufacturer and sell his new core and locks. In 1938, Best and his company would relocate to downtown Indianapolis, Indiana, where the company remains to this day.
In 1966, Frank Best passed away. Frank left behind quite a legacy, accumulating 58 patents for locks, keys, and lock related equipment throughout his life. Frank Best’s oldest son, Walter, became President of Best in 1966 and held that position until 1994. Best Lock Corporation’s mechanical lock hardware line was fully developed during Walter’s tenure. According to Best company literature, Walter saw sales grow from $4.5 million in 1966 to $104.6 million in 1994. Keying systems using Best’s “small format interchangeable core” became synonymous with many institutions such as schools, hospitals, colleges and universities, government offices, and even military installations.
Russell Best, Frank’s grandson, acquired Best Lock Corporation in May of 1994 from his father Walter. In November 1997 Best Lock Corporation became Best Access Systems. On November 25, 2002, Stanley Works purchased all of Russell Best’s holdings to become the new owner of the company. The company became Stanley Security Solutions although they continued doing business as Best Access Systems. In 2010 Stanley Works and Black & Decker would merge to become Stanley Black & Decker. On February 22, 2017, Best was acquired, along with other Stanley Black & Decker mechanical security businesses phi Precision and GMT, by dormakaba. The deal was worth $725 million. Throughout it all, Best Access Systems remains one of the premiere lock manufacturers in business today.
Man oh man did we get some details wrong. Not long after this was posted, we received a copy of Frank Best’s obituary (posted below) from Zach J. Olson through a mutual friend. A few corrections therefore must be made using this new information:
- Frank Best was actually a teacher, not a janitor, at the high school.
- Frank Best’s genius wasn’t just limited to locks.
The story of Frank being a janitor is one that is repeated throughout this industry; in fact, it’s the first sentence on the current BEST Access “About BEST” web page. I hope this was in error on their part because honestly, the true story is far more interesting and far better than what I, and many others, have been told about the man. We apologize for any confusion we may have created. Thank you for the update Zach!
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Patent Number: 3,499,302 (Google Patents)
Filing Date: March 1, 1967
Issue Date: March 10, 1970
Inventor(s): Roy C. Spain, Roy N. Oliver, Elvis C. Flora, Paul A. Powell
Linus Yale Jr. formed the Yale Lock Manufacturing Company with Henry R. Towne in 1868. Yale flourished and by 1953 the company decided it was necessary to decentralize the manufacturing facilities of the Yale Lock and Hardware division. New plants were built in Gallatin, Tennessee, Lenoir City, Tennessee, Monroe, North Carolina, and Salem, Virginia. One employee of the Salem plant, which focused on automotive and industrial locks, was Roy C. Spain. By all accounts, Spain was a gifted inventor. Spain had many patents issued between the 1940s and 1960s. These patents included:
- 3,094,039 (Key Bitting Machine)
- 3,080,744 (Side Bar Cylinder Lock)
- 3,002,268 (Side Bar Cylinder Lock Assembly)
- 2,720,102 (Portable Lock)
- 2,702,468 (Dust Cover For Locks)
- 2,690,070 (Rotary Tumble Cylinder Lock)
- 2,660,876 (Side Bar Cylinder Lock)
During his time at Yale, Spain partnered with Paul A. Powell to form a tool and die company known as the Mechanical Development Company. Originally started in Spain’s basement, the company would eventually relocate to a standalone building not far from the Yale plant in Salem. Sometime during this period, Elvis C. Flora and Roy N. Oliver joined the Mechanical Development Company. According to a Medeco company presentation, Flora and Oliver, upon learning that Spain had created a prototype of key that used angular cuts, urged Spain to fully develop the his lock concept. Spain would eventually leave Yale and devote himself full time to his company and idea. Not long after this, the Mechanical Development Company produced what would become the “Medeco Original”, or Medeco’s original high security platform.
Prototypes of the design were manufactured and then sent to various manufacturers throughout the U.S., presumably to gauge interest as well as find out if any manufacturer was interested in mass production of them. No manufacturers were, however, believing that it couldn’t be manufactured in an economical and consistent manner. Since the group had already created a number of prototypes and proven to themselves that it could be, they decided to begin selling them under a new business with a new name: Medeco, taking the first two letters from the original companies name.
Medeco became wildly successful marketing and selling their “original” product and would eventually become the largest manufacturer of high security locks in the United States. At some point in the early 1970’s, Spain, then President of Medeco, issued the infamous $10,000 challenge to anyone who could pick open their cylinder. NYC detective Bob McDermott successfully picked one cylinder but since he could not do it twice, which the challenge supposedly stipulated, he was not able to cash in. McDermott was hired as a sales rep for Medeco shortly thereafter.
In 1974, Oliver became the president of Medeco, which soon opened a 58,000 square foot facility in Salem. This facility is a few thousand feet from the banks of the Roanoke River. Roanoke is an Algonquian word that, according to English explorer John Lawson and most in academia, translates to… money. Medeco’s success continued and they soon became the preferred choice of many U.S. government facilities, including embassies abroad. In 1984, Medeco was sold to Hillenbrand Industries Inc. In 1998, Hillenbrand Industries sold Medeco to ASSA ABLOY. Today, Medeco still operates successfully as an ASSA ABLOY group company.
Medeco’s innovation didn’t end with their original design. In 1988, they were granted a patent (4,732,022) for the original design’s successor: Biaxial. The successor to the Biaxial, the Medeco3 or M3, was granted a patent in 2005 (6,945,082). Other patented platforms included KeyMark (Re. 35,518 E) and KeyMark/Medeco X4 (8,186,194 B2).
And as for the Mechanical Development Company? Their existence didn’t end with the creation of Medeco. Powell’s family now owns the company and they’re still in business in Salem, not far from Medeco’s current headquarters and the original Yale plant, less than a thousand feet from the Roanoke.
Special thanks to Billy B. Edwards for his insight on some items discussed in this article.
We’ve added a comprehensive list of patented lock and keys to our High Security Resources page (direct link here). This list contains patented keys and locks starting in 1987 with the expiration of the Medeco “Original” patent all the way through 2031, when the Abloy Protec2 utility patent will expire.