BACK TO BASICS The Rascally Rabbet Mortise Bit Key Lock When the tumblers are raised to the prop- er height, the narrowest part of each lever gate lines up with the fence. In other words, the tabs on the tumblers are no longer block- ing the fence from moving from side to side. At this time, the key also begins to move the bolt to the locked or unlocked position. Look at the bottom of the bolt in Figure 7. You’ll notice a cutout that looks like an upside-down letter V. As the key continues to turn, part of the blade of the key hits one side of this cutout and begins to move it from one side of the lock to the other. As the bolt moves to the end of its travel, the key continues turning and the tumblers begin to move downward toward their rest position. As the tumbler springs push them down, the fence becomes trapped on the other side of the tabs in the gates, either locking or unlocking the door. The key con- tinues turning back to its starting point and can now be removed. With a pin tumbler cylinder, the size of the tumblers dictates the depth of the cuts on the key. With lever tumblers, the gates are all the same size, but their position on the tumbler dictates the depth of the cut. There are many different types of levers. Most of them don’t enclose the fence with- in them as ours do here. Usually the gates “A ‘rabbet’ is a carpentry joint that’s often used in drawers and cabinets. They’re usually used to join two pieces at right angles, but they can also used as end-to-end joints. are in different positions along the edge of the tumbler and are open-ended; the fence slides into them. Looking at Figure 8 again, the bottom two tumblers have their gates in the same place. At the bottom semicircular part of the tumbler, there is a very subtle differ- ence. This part of one tumbler is slightly bigger than the other. If you were to insert a blank key into the lock and turn it, you’d see one gate higher than the other, both blocking the fence. You can change combinations on lever tumbler locks by switching the tumblers around and cutting a key to fit. Whether you can do that depends on a few things. First, can you take the lock apart without dam- age it? Second, is the lock so cheap that it’s Advice on Antiques If anyone brings you an antique lock of any type, think before you work on it. Shake it and listen for anything rattling around inside that might be a broken part. Point this out to the customer so he knows that something could be broken before you’ve opened the case. Do this while he’s still in your shop. If you give him a receipt for the lock, note that on it. Screws that haven’t turned in decades may snap and need to be drilled out, re- tapped and replaced. Most people don’t have a problem with this, but you want to mention that you might have to do it. It’s also very important that you don’t do anything to the finish on the lock unless you are asked to. Don’t wire brush, clean up or polish any parts that are visible when the lock is reinstalled. The reason is that some people want the hardware to look its age so that it matches what else is on the door or in the house. One more thing: Make sure you charge enough, since some shops won't touch antiques. — TW easier to replace it, like most lever mailbox locks? Third, do you have enough tumblers to switch around in a way that effectively changes the combination? In our example, the best I could do would be to switch the second and third tumblers and cut a new key. There’s a possibility of altering the tumblers with a file, but that’s permanent, and I wouldn’t recommend even trying it. In case you’re wondering, the first tumbler has a gate that’s completely open. It doesn’t stop the bolt from moving. That tumbler controls the movement of the other two and acts as a spacer. What’s Ahead In my next article, I’ll go through fitting a key to this lock. This can be a little te- dious, but the reward comes when you turn the key and it operates for the first time. I’d like to make two requests for in- formation. First, if any of you are lock collectors and have more information on the origin of the rabbeted lock and why it was designed that way, drop me a line at [email protected]. Second, I’m looking for an advertisement I saw in a 1940s to 1950s trade magazine. It was probably the Locksmith Ledger or Keynotes. The ad was for a wind-up bell type exit device that was either a Best Model B, or the Detex equivalent. The ad had the line “Now you can legally lock fire doors!” What I need is a clear picture of the ad and the month and year of publication, or a shot of the cover. Even better, I’d buy the magazine from you if you’re willing to sell it. Either way, I’ll credit you in the article. bove address. Wiersielis, CPL, CFDI, ore than a quarter y of experience, hav- rked in most phases e trade throughout the ork metropolitan area. 54 KEYNOTES SEPTEMBER 2014 WWW.ALOA.ORG
