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The Obsolete Mortise Lock

January 26, 2015 builders hardware / door hardware / Door Repair / Keys and Keying / Lock Repair / locksmith

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Nothing lasts forever. Like manufacturers of other mechanical devices, lock companies periodically update their products to be consistent with current technology. They do this to make better, safer, more reliable products, and also to remain competitive in the market place.

Sometimes these new, updated products are backwards-compatible with older models of the same brand, sometimes not. In the case of mortise locks I can say with some confidence, mostly not. One cannot replace a Schlage K series mortise lock body with an L series and expect the trim to work. The same is true of the newer Sargent 8200 vs. the older 8100 and the Yale 8800 series vs. the previous 8700 series. As these older locks age and must be replaced these differences can become a problem, since the existing trims and cylinders on site may not be usable with the new lock bodies. And there are still plenty of these older lock bodies out there. Case in point, although the Yale 8700 series was discontinued in 2006, one facility I know is filled to the brim with these mortise locks.

Although I foresaw that they would not be able to use the existing trims with their new locks I failed to anticipate that the existing cylinders would also be incompatible. But they were and here is why. On the left the cam that works with the Yale 8700 is in the process of being removed from a Medeco small format interchangeable core (SFIC) housing. In the first picture below, the correct cam has been installed.

In the second picture you can see that the new cam is not only thinner than the old cam, it’s also slightly longer. There is no way that old cam is going to work. Luckily, on a Medeco SFIC housing the cams are interchangeable, unlike most others on which the cams are permanently attached.

Please visit my friends’ site:

http://www.americanlocksets.com/mortise-locks-c-38_159.html

Now I’m waiting to hear about the other SFIC housings on the job that have their cams staked on. But one cluster at time, eh?

Locks and Keys Grow Old Together

July 8, 2014 Keys and Keying / locksmith

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I never cease to be amazed when someone tells me their car won’t start and then they say,

“Well, it started yesterday.”

What sense does that make? I ask you. Is today yesterday? I think not.

Yes, indeed, time wears out almost everything: clothes, human bodies, tree limbs, stones, car batteries … and locks and keys as well.

Keys and locks are for the most part both made out of brass. Most pin tumblers are brass and most keys are either made of brass or ‘nickel silver,’ whatever that is. Brass is a self-lubricating metal, producing verdigris as it oxidizes. Nevertheless, as brass slides across brass again and again, particle by particle the substance of key, pin tumbler and lock cylinder are gradually worn away.

This manifests in several ways. I’ve made a list of the most easily observable below:

The keyway gets larger, and the fit that was once pleasingly tight is now loose and sloppy
The key gets smaller, aggravating the sloppiness
The peaks are worn off the blade of the key, but his only affects the appearance of the key. It is the valleys that are important.
The blade loses height because the bottom of the blade is worn
The plug gets smaller, allowing the upper and lower pin chambers to be at unintended angles
The bottoms of the pin tumblers, once rather pointed, become rounded, thereby shortening the overall length of the pin
Grooves are worn into the plug by the top pins

Eventually the old key that works relatively well in the old lock sits at an odd slant, its tip raised and its bow drooping because of the sloppy keyway and worn bottom of the key blade. When one turns the key it twists in the keyway because the key is thinner than it once was, allowing all the pins to drop a little in their chambers. But since the key and lock have been used together for so long, this one key may continue to operate the lock for a long time.

However, if one cuts a new key using the old as a template, the new key will likely not work well because it will not sit or twist the same way in the keyway. If one attempts to decode the old key, one usually finds it to be a difficult task because keys tend to wear unevenly. But even if a key cut true to the original manufacturer’s specifications is produced it will quite likely not work well in the worn lock, because it will not put the pins in the positions the metal of the lock has become accustomed to.

This tends to confound the user because the differences between the old key and the new are measured in thousandths of an inch and are not easily discernible to the untrained eye. Locksmiths are then asked the question,

“Why doesn’t the key you cut for me work? The original does.”

And when the locksmith suggests it might be time to buy a new lock, s/he may hear,

“But this lock has worked fine for thirty years! And my key works great!”

Next, of course, they are likely to call you a bad locksmith, but there is no help for it if they won’t listen to the truth that their beloved lock, their venerable old daily friend, has outlived its ability to do its job, sad, but true.

The locksmith may enjoy some (albeit perverse) solace in the fact that eventually the key will stop working in the lock altogether, or will become so thin and frail that it breaks off in the lock, and at that point the user will realize that something has indeed gone amiss. If it happens in the middle of the night, and the locksmith is on call, s/he may get substantially more than vindication out of the deal.

Hint: Vindication is not all it’s cracked up to be.

The Keyway: Gateway to the Cylinder

July 3, 2012 access control / Keys and Keying / security hardware

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The keyway is the shape of the keyhole of the lock cylinder into which the user inserts the key. The keyway is designed to allow only keys of the correct shape to be inserted such that, when properly made, they will align the pin tumblers properly and operate the cylinder. If you view a key from the tip, you can see how the shape of the key corresponds to the shape of the keyway.

The theory behind the keyway is to let only certain kinds of keys in and keep all others out, and keyways do this with varying amounts of success. A variation on this idea is the “sectional” keyway system in which keys of slightly different keyways are allowed to “pass” into the cylinder keyway. See the diagram of the Schlage hierarchy of keyways below:

The keyways shown at the bottom of the chart are designed to fit in only one keyway. Unlike the keyways shown in the top two rows, actual locks have the keyways in the bottom row. The keyways shown in the second row could be called sub-master sectional keyways because keys cut on blanks of these keyways will each pass several of the keyways in the bottom row. Keys cut on the “L” keyway shown at the top of the chart will pass all of the keyways below it. This keyway is designed to be used only at the level of Master or Grand Master key.

Unfortunately, some key duplicators use the “L” keyway key blanks to cut keys of any sectional keyway they may currently not have in stock. This shoddy practice degrades the security of a master key section that depends on sectional keyways for security.

Restricted Key or Restricted Keyway?

Keys can be stamped with the words, “Do Not Duplicate” or “Property of [insert name of institution or government agency here],” and that may stop some honest people from getting the key copied. The term, “restricted key,” however, usually means factory restricted keyway, and a factory restricted keyway can effectively inhibit unauthorized key duplication.

How Does a Factory Control a Keyway?

The most effective way to control unauthorized key duplication is to make the key blanks as difficult to get as possible. Key blanks are like blank paper to a copier. Imagine copy paper protected by a patent owned by a paper mill. The only place to get the paper would be the paper mill. Thus, one of the ways security hardware manufacturers protect a keyway is to protect it by patent law. Part of that protection is aggressively pursuing anyone who violates the patent with lawsuits and other legal instruments to prevent patent infringement.

Another way factories protect keyways is to keep records of who is using what keyway and where. Many companies have restricted key programs – Schlage Primus, Kaba Peaks and Medeco are a few examples. Factories may keep signatures of end users on file. In this case, requests for restricted products must be accompanied by a document that is signed with the correct signature or the factory will not release the product.

Some restricted keys come with an ID card that authorizes the card holder to get keys made. This is less secure than key duplication that is controlled at the factory, but it is a step up from keys that anyone can get made at Home Depot.

Keyways and Key Bumping

In order to use a bump key to open a lock, the key bumper needs to have the right blank. You cannot bump a cylinder with a bump key that has the wrong keyway. It won’t go in. Therefore, having a lock that has a somewhat rare keyway is a very easy and inexpensive way to make unauthorized entry by key bumping difficult. Most of the people out there bumping locks open are not the brightest bulbs in the lighting fixture. Challenge them with a hard-to-identify keyway and they will most likely be defeated.

When Your Key Won’t Turn

April 2, 2011 door hardware / Lock Repair / security hardware

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Someday you might come home or go to open up your business and find that your key won’t turn at all, not even a little. There are several reasons this might occur.

At right, illustrations show the operation of a standard pin tumbler lock. When you insert your key, the key raises the pins to the point where the division between the top pins and the bottom pins aligns with the division between the plug and the bible of the cylinder, allowing the plug to turn.

Sometimes dust and dirt collect inside the lock cylinder. When that happens the dirt can cause the pins to stick in a partially raised position, preventing the plug from turning. In most cases a spritz of dry lubricant will be sufficient to free up the plug and allow you to open your door. Simply spray the lubricant into the keyway and insert the key a few times to work the lubricant into the mechanism. If this method does not work you may need to use a more solvent-based lubricant like WD-40 to loosen the dirt. Locks exposed to the elements sometimes collect a lot of dirt.

If your key will only go in part way, this could still be the same problem, or there may be an obstruction in the keyway. Illumination of the keyway reveals that the bottom pins hang down into the keyway. In the event that lubricating the lock is ineffective, slide a thin piece of wire into the lock along the bottom of the keyway, avoiding the pins, and feel for an obstruction. If the piece of wire will not go in as far as the length of the blade of your key, there may be an obstruction present. At this point you might want to call a locksmith, however, you can gently work your way past the pins and try to go over the obstruction in order to try to coax it out. This process can take a lot of patience and skill, and it is possible to make the problem worse if you are heavy handed with the pins.

From Wikipedia

Should lubrication fail to free up your lock and you can find no obstruction, your lock may have a more serious malfunction, such as a pin chamber worn enough to allow a pin to get stuck at an angle, or a corroded pin that is frozen in place and will not budge no matter what. In these cases you need a professional to gain entry for you and repair your lock. If you succeed in freeing up your lock but find that the problem is reoccurring with increasing frequency, it’s probably time for you to replace your cylinder.

The Obsolete Mortise Lock

Locks and Keys Grow Old Together

The Keyway: Gateway to the Cylinder

When Your Key Won’t Turn

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