Experiencing the New Von Duprin Chexit

Chexit door label from Chexit installation instructions.

Chexit door label from Chexit installation instructions.

Many of us discovered to  our surprise and chagrin that the new motorized Von Duprin Chexit does not automatically release outside mechanical lever trim (Von Duprin 996L) as did its predecessor.  In those days the Chexit was both a delayed egress and access control device all in one if you simply added a lever trim, … but those days are gone.

In order to get that function these days one needs to add the E996L electrified trim, and also the part number 040193-00 cable to connect the E996L to the Chexit PC board.  To our further surprise and chagrin we also found that if we ordered exit only Chexits from the factory they did not include the cable for the trim.  The cables are only provided if you order the Chexit from the factory with trim.  So if you stock your Chexits exit only it is no longer a matter of just shipping a trim with a device; instead it is three separate but equal chances to forget to include the right part.

On the bright side, since it is motorized, the new Chexits draw less current and will probably be more reliable than the previous solenoid-driven version. This means a less serious, less expensive power supply, less need for high capacity, high gauge, high cost wire and greatly increased workable wire run distances – all good things.

There is also a kind of, sort of exception to the E996L necessity I stumbled upon. Recently I was involved in an application where the installer was replacing a mortise exit device and wanted delayed egress from the push side and free ingress from the pull side.  Luckily it was a mortise device, so all I had to do was provide a Chexit mortise exit device with blank escutcheon (passage function) trim because THE MORTISE LOCK ACTS INDEPENDENTLY FROM THE CHEXIT ON THE TRIM SIDE. Cool. 🙂

Bear in mind that  the Chexit remains active while people are using the passage function trim to get in, so if they happen to depress the touch bar, say by bumping it up against the wall for two seconds, they may activate the Chexit alarm.   Von Duprin Tech Support suggested a palm switch on the trim side to activate the inhibit circuit in the Chexit while a person enters from that side.

 





It was fun, easy, and I looked like a … Hardware Genius.

Choosing a Delayed Egress System: Self-Contained, or Built from Components?

Delayed egress is a process that delays unauthorized exit from a space while complying with NFPA 101 life safety code.  Use of this process is strictly regulated with the help of building inspectors and fire marshals across the United Sates.  With that in mind it is always a good idea to get your local AHJ (Authority Having Jurisdiction) on board whenever you are planning to install delayed egress on an opening.

When you beginning planning your delayed egress system you will find that many systems on the market are self-contained.    These could be delayed egress electromagnetic locks or electrified delayed egress exit devices.

Here are some examples of self-contained delayed egress maglocks:

  • SDC 1511S
  • Schlage Electronics M490DE
  • Dynalock 3101C

Here are some examples of self-contained delayed egress exit devices:

  • Detex V40 EE
  • Von Duprin Chexit
  • Sargent Electroguard

delayed-egress-anatomy
Almost all delayed egress systems are made up of the same components:

  1. Delayed egress timer and relay logic board
  2. Initiating Switch (to initiate the delayed egress process)
  3. Audible alarm
  4. Signage
  5. Reset switch
  6. Optional bypass switch
  7. Fire Alarm interface
  8. Power supply
  9. Locking device

Therefore it is possible to construct a custom delayed egress system from components.  Later I’ll talk about why you might want to choose a built-from-components delayed egress system instead of a self-contained one.   The following sections describe each part of a built-from-components delayed egress system.

Delayed Egress Timer and Relay Logic Board

This board is UL Listed and specifically designed to perform all delayed egress functions in compliance with life safety code.   Here are some examples of component boards for delayed egress:

  • Securitron XDT-12 or XDT-24
  • Seco-Larm SA-025EQ

The board is the brains of the delayed egress operation.  It has contacts to wire in switches for delayed egress initiation, fire alarm interface and system reset, timers to control nuisance and egress delay, and relays to control locks and notify external devices.

There are also delayed egress controllers that offer more features.  The following may include the delayed egress timer/relay board and some other required feature(s) such as the initiation switch or the audible alarm.

  • Alarm Controls DE-1
  • Security Door Controls 101-DE
  • Securitron BA-XDT-12 or BA-XDT-24

Initiating Switch

The switch that initiates the delayed egress process shares several characteristics with any request-to-exit switch.  To comply with life safety regulations it must require no prior knowledge to operate; it must require no more than one motion to operate; and it must be placed in relation to the door according to life safety standards in your local jurisdiction.  I think that the best possible initiation device is a mechanical push bar with a switch, such as the Adams Rite 8099-M or the Securitron EMB.  In a panic situation it remains obvious that to get out, one must push on the bar, and because it is mechanical it is unaffected by power outage.  If it is wired to open the contact when pushed, if the wires leading to it are cut it will initiate the delayed egress process.

In rare circumstances where it might be permitted, the locking device might be a fail safe electrified mortise lock that is locked on both sides, inside and out.  Then the initiation switch might be a palm switch next to the door.

Audible Alarm

The mandatory audible alarm sounds for 15 seconds before the delayed egress controller releases the locking device to allow exit.  It’s loudness must be between 81 and 88 decibels.  In some jurisdictions the alarm must be manually reset at the door; in others it may be self resetting via timer or door position switch.  Yet another reason to have a heart-to-heart talk with your local AHJ when designing your delayed egress system.

Signage

The wording on the mandatory sign must comply with life safety code.  There are minor variations in wording.  I suggest buying a sign that is part of a delayed egress system.  The sign that comes standard with the Von Duprin Chexit is readily available as a separate part.

Reset Switch

As mentioned in the “Audible Alarm” section above, a delayed egress system reset switch located at the door is mandatory in some jurisdictions.  Check with your local AHJ.  In some jurisdictions delayed egress systems are allowed to be reset by remote switch or other means, such as a door position switch.

Any kind of momentary contact switch will do the reset switch job, but delayed egress system reset switches located at the door almost always require some kind of security to prevent unauthorized resetting.   Standalone keypads or key switches are often used for this purpose.  Delayed egress systems can also be integrated into existing access control.

Optional Bypass Switch

Not required but often needed, the optional bypass switch allows authorized personnel to exit without triggering the delayed egress system.  Again, any momentary contact switch will do, but usually some security is required.  If you are using a keypad as the system reset switch and the keypad has more than one relay, you can program the second relay to be the bypass switch.

If access from the exterior side is required a bypass switch is required on that side.  Sometimes security is not needed from the exterior side.  In that case a simple momentary contact pushbutton will do the job.

Fire Alarm Interface

The mandatory fire alarm interface allows enables fire alarm panel to deactivate the delayed egress system immediately in the event of a fire alarm.  This is an integral part of the life safety code that allows a delayed egress system to exist.  Therefore, if your building does not have a fire alarm panel, without special permission from the local AHJ you cannot have a delayed egress system.

Power Supply

All delayed egress systems I have had experience with run on low voltage power that comes from a low voltage power supply.  Generally delayed egress systems require regulated and filtered power at 12 or 24 volts.  Delayed egress controllers draw very little current, but as will all electrically operated systems, the current draw of all attached devices must be taken into account when selecting a power supply.

Locking Device

The locking device must be electrically locked and fail safe from the egress (interior) side.  The most frequently used locking device in a component based delayed egress system is the electromagnetic lock.

Why Build a Delayed Egress System?

Why would you put together a delayed egress system from components when there are so many good self-contained systems?

  1.  To Save Money.  Piecing together a delayed egress system can be significantly cheaper than buying a self contained delayed egress system.
  2.  To take advantage of existing hardware.  For example, if there is already an electromagnetic lock on the door, adding the other components is relatively easy.
  3. Conditions at the door prohibit use of a self contained delayed egress system.  For example, door size or the presence of existing hardware may require the installer to seek a more creative solution.

 





Bottom line, unless you have a prison, you cannot lock ’em in.  Well, not without permission.  🙂

Door Hardware Triage

The Medical Metaphor

medicalAs previously published in Doors and Hardware Magazine, Feb. 2016

As in the medical profession, correct diagnosis of door hardware problems is wholly dependent upon the knowledge, skill and powers of observation of the person whose job it is to correct the problem.  “The devil is in the details,” they say, and it is never truer than when said in reference to doors and hardware.

Another old saying, “ignorance is bliss,” can be liberally applied to who those innocent building occupants and visitors who think that the answer to a lock that is not latching is to slam it until it does – or until the hardware falls off, whichever comes first.  Yet by the same token, door hardware technicians who fail to look at door hardware problems holistically are equally blissful.  If you have ever seen the latch hole in an ANSI strike enlarged to include half the head of the bottom mounting screw in order to remedy what is clearly a hinge problem you will understand what I am talking about.

The above occurs because the technician sent to solve the problem is guilty of treating the symptoms while failing to diagnose the disease.  He or she observes that the latch is making contact with the strike too low to drop into the strike hole as it should, but does not question why this is happening.  This example is a simple one, but the principle applies to more complex problems as well.

Method

A great way to make sure you correctly identify a door hardware problem on the first visit is to have a consistent method of examining the total opening.   An example follows:

  1. If possible, speak with the person who has reported the problem, or better yet, meet with them at the opening so that they can show you what the problem is.
  2. As you approach the door, visually check the gap around the edges of the door on the top and both sides.  (The gap should be one-eighth inch.)  If the gap is greater in one place and less in another, the problem may be a bent hinge or misaligned frame.
    Open the door.  How does it feel?  Does the door itself stick?  If it has a latch, is there resistance when you turn the lever to retract it?  Do the hinges groan or squeak?
  3. Inspect the door for dents and abrasions.  For example, scratches at the top of the lock-side edge may indicate bent or loose hinges.   Dents may indicate attempted forced entry:  check for damage to internal lock parts.  A dent in the gap between the door and frame above the top hinge may mean an object was placed there.  The frame may be damaged and/or the top hinge may be bent.
  4. Inspect the hardware for damage, missing parts and/or wear.   If it is a hollow metal frame, are the silencers installed?  If there are no silencers the door will not align properly and the lock will not latch correctly.  Is the door closer leaking?  Does the door closer arm move smoothly?  Are the hinge screws all present and accounted for, and are they tight?  If there is a latch, there probably is a drag mark on the strike.  Does the drag mark reflect correct alignment?

In other words, look at the door, the frame and the hardware thoroughly and completely, and always do it the same way.  That way you won’t fix one problem just to return the following week to fix another problem that you missed.strike

Tools May Be Required

To identify a door hardware problem you may find it helpful to use instruments or tools.   For example, a carpenter’s level can help you determine whether a door or frame is level or plumb quickly and accurately, and a carpenter’s square can show immediately if the frame is true or sprung.   A tape measure may be helpful to check if hardware is correctly located, whether or not the gap between door and frame is consistently one-eighth inch, and if one leg of the door frame seems to be longer than the other.

One problem most swiftly identified using a carpenter’s level is positive pressure.   If you detach the closer arm and tape back the latch on a door that is level, and it swings open seemingly of its own accord, chances are it’s a positive pressure issue.  Positive pressure occurs when the air pressure inside the HVAC ducts is greater than the pressure outside, causing air to be constantly forced out of the structure.  Positive pressure can be powerful enough to prevent a door closer from closing the door, and sometimes the only cure is when the HVAC technician changes the settings on the air circulation system.

The positive pressure issue is one of those door hardware issues that may require someone besides a door hardware technician to fix.

Waiting For The Electrician

Problems with electro-mechanical and electronic locking systems, like positive pressure issues, may require a low voltage or electronics specialist to solve in addition to a door hardware technician.  For liability reasons it is important to use technicians who are appropriately licensed as required in your locality.

Often these problems are due to mechanical as well as – or even instead of – electrical or electronic issues.  Therefore the best situation for electronic or electrical door hardware triage is when the technician called upon to fix a problem is skilled in all three disciplines. Out in the world we are finding locksmiths that have their low voltage electrical technician license and a working knowledge of how to troubleshoot or program an access control system, systems integrators who can disassemble and repair a mortise lock, and even electricians who can adjust a door closer or repair an exit device.

This is a phenomenon driven by a market that desires to have one technician who can do everything, both for convenience and economics.  In any event, a technician equally skilled in these areas solves the problem of cross discipline communication.  If you’ve ever had to explain the difference between fail safe and continuous duty electrified door hardware to someone who just does not get these concepts you will understand what I’m talking about.

For this reason alone it behooves one in the door hardware repair and installation business to learn as much as they can and get all the credentials they need to be able to service all the door hardware out there in today’s electric and electronic world.

Closure

The age of door hardware in which we work today is the age of the renaissance woman or  man, student of many skills.  However, diagnosing the often complex ailments of doors and door hardware takes more than skill and knowledge:  it requires mindfulness, openness, resourcefulness and humility.  It is not only necessary to know what could go wrong (and doubtless will, according to Murphy’s Law); it is necessary to be aware enough to observe all the symptoms, to be open to all possibilities and to be imaginative in creating solutions.  One must also have the humility to realize that it is not possible for anyone to know absolutely everything.  Sometimes the most useful tool at your disposal is your mobile phone.  A call to factory tech support can often save hours of fruitless aggravation.

 





No man is an island – but some men belong on one. 

Field Reversing the Adams Rite 4510 Latch

4510

Adams Rite 4510 Latch

Although Adams Rite tech support might not want to talk about it*, depending on who you talk to there, the 4510 series latch lock, like its predecessor the 4710, is, in fact, field reversible.  Following are the steps to do so.

First, try to choose a clean work surface in an enclosed space, just in case the springs go flying.

1. Remove the retaining plate screws using a #1 Philips screwdriver.  Place the screws on the work surface where you can find them later.

screws

2. Carefully remove the plate from the back of the lock body that holds the bolt, auxiliary dead latch and latch springs in place.   The latch springs exert tension against this plate, so remove it with care.

3.  Using the tip of the screwdriver, move the locking lever pin so it lines up with the slot in the lock body and gently push the front of the bolt with your thumb.  The bolt, auxiliary dead latch and deadlock arm assembly will slide out of the back of the lock body together.

SlideLatchOut4. Remove the pin that attaches the deadlock arm to the bolt assembly.

See the exploded view of the old 4710 latch below for more detail.  The newer 4510 is similar if not identical to the 4710.

Caution:  There is a spring inside the bolt assembly that actuates the deadlock arm.

5. Remove the deadlock arm and spring.

pin1

6. Turn the latch over and install the deadlock arm and spring on the other side.  You will need to hold the deadlock arm and spring in position. When the spring and all are in position, install the pin.

7.  Slide the bolt assembly into the lock body.

pin9. Place the smaller spring into the auxiliary deadlatch and the larger spring in the bolt.

8.  Slide the auxiliary deadlatch into the lock body.

9.  Install the retaining plate and screws.

 

 

 

 

Detail from discontinued Adams Rite 4710 Latch parts breakdown, from Adams Rite parts book

Detail from discontinued Adams Rite 4710 Latch parts breakdown, from Adams Rite parts book

disassemble

* I recently related this procedure to a locksmith who said she had called Adams Rite tech support who told her the unit is not field reversible. This is understandable because the installation instructions do not discuss reversing the handing.

The Pressure’s On

balloonPositive Pressure Issues

Sometimes doors are required to perform conflicting functions simultaneously.  For example, in order to comply with the American Disabilities Act a particular door may be restricted to a door closer that requires as little as five pounds of opening force.  This same door may be required to lock automatically without fail.

One solution could be to use a non-hydraulic, motorized power operator (automatic door opener) instead of a standard hydraulic closer.  Since many non-hydraulic power operators do not depend on a spring for closing force it is possible for them to have an ADA compliant opening force and also exert a closing adequate to close and latch the door.  Most power operators that fit this description must be installed by AAADM certified installers.

Without the magic fix of the non-hydraulic power operator, all a door technician can do is fine tune the door so that it swings perfectly and is perfectly balanced; fine tune the locks, hinges and door closer to peak performance under the opening force restriction; and pray there isn’t a positive pressure or wind issue.

One caveat:  deprived of electricity, a non-hydraulic power operator will neither open nor close the door.

Positive pressure HVAC operation is a prime example of how the intended function of a door can be impeded or prevented by the normal operation of building infrastructure.   Positive pressure in a building is accomplished by using the HVAC system to add air from outside the building to the air that is already in the building.  As with a balloon, the added air pushes outwards in all directions.  When an exterior door is opened, air flows out through the open portal, acting as an invisible barrier that keeps outside air out.

Unfortunately positive pressure acts like a constant wind pushing on the inside of the exterior doors.   Since almost all exterior doors swing out, the net effect of positive pressure HVAC on exterior doors is that of blowing to doors open and/or preventing them from closing.

The non-hydraulic power operator idea discussed above can usually solve the problem, but I have had some success adjusting door closers to compensate for positive pressure situations.  I have found that a slow swinging speed followed by a fast latching speed will often accomplish the mission.  This solution, however, can create other problems such as creating a wider time window for unauthorized persons to enter while the door is still shutting, for example.

I have found no reliable fix for an opening subjected to positive pressure that must comply with ADA reduced opening force requirements; however, since positive pressure on out-swinging doors inherently reduces opening force, there is some hope.

In the best of all worlds, door hardware technicians and HVAC technicians work together to coordinate positive pressure ventilation needs with security and ADA compliance requirements.

Excerpt from Tom’s article “Butcher, Baker, Door Hardware Technician… ” published in the February 2015 issue of Doors and Hardware Magazine, magazine of the Door Hardware Institute.

The Obsolete Mortise Lock

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.

DSCN4430DSCN4432

 

 

 

 

 

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?

The Wrap-Around Door Reinforcer

4CW2A wrap-around door reinforcer is a metal sleeve that slides over the door at the lock prep to conceal damage and/or reinforce the door.  They are a quick and handy solution when wood doors are damaged by forced entry and are often installed to strengthen new wooden doors against forced entry attempts.

In my experience a wrap does not really deter forced entry, but it does limit the damage done to the door.   I have found that when wood doors equipped with wrap around door reinforcers are burglarized, often only the wrap and the lock need replacing, not the whole door.   As with all door security hardware, if your lock is installed in a wrap-around door reinforcer and your neighbor’s lock is not, a would-be burglar may choose to break into your neighbor’s place instead of yours; however, this hypothesis is dependent on the highly dubious notion that a burglar is behaving rationally.  If the person were behaving rationally they would not risk their freedom and personal safety breaking into to somebody’s home to steal  their iPad or PC and selling it for chump change to their drug dealer.

Another benefit to using wrap-arounds is that they can act as a drill guide for lock installation.  Be careful, however, not to let the hole saw chew up the wrap.  Also, especially with stainless steel wraps, be sure not to let your drill bind up with the metal at high speed.  Injury would be likely.

Wraps are typically used on wooden doors, and while it is possible to use them on hollow metal doors, they never seem to fit quite right without a fight.  It seems that hollow metal doors measure exactly 1-3/4 inches thick whereas wood doors tend to measure closer to 1-11/16 inches.  Variations in door thickness affect the way a wrap will fit (or not fit) on a door.

A wide variety of wrap-arounds have been created to accommodate various locks and conditions.  Don Jo Manufacturing currently carries the largest assortment, and if a new kind of lock by a major manufacturer emerges, they are pretty quick to design a wrap for it.  To get the right borewrap for your application you need to know:

  • Door thickness
  • Size of the wrap you want
  • Diameter of the lock bore
  • Backset
  • Finish
  • Through-bolt holes (yes or no)

(see illustration)

Standard door thicknesses for wraps are 1-3/8 inches and 1-3/4 inches.  Some models of wraps are available thicker doors.   Wraps come in a variety of heights, but height is usually determined by the kind of lock the wrap is designed for and the backset.  See the illustration for bore, through-bolt hole and backset details.

For other wraps you may need other dimensions.  For example, Don Jo makes a number of wrap-arounds for interconnected locks and these (naturally) have two bores cut in instead of one.   If you need a wrap for a mortise lock you may have to change the trim on the lock to make it work, or you might have to drill lever, cylinder and thumb turn holes into a blank wrap to customize it to the lock you have.  See my warning about hole saws and stainless steel above.  I earned myself sprained fingers that way once.

I used to joke about certain doors that they could use a door sized wrap.  Then some enterprising individual actually brought one by.  The idea didn’t go anywhere, as far as I know, but it was a good concept:  one wrap covered the door completely in sheet metal and another covered the frame.  Still, at that point why would one just buy a hollow metal door and frame?

And that about wraps it up.

Compact Electric Strikes

A common problem with installing electric strikes is cavity depth – that is, how deeply you need to cut into the frame (or wall) so that the electric strike will fit. For most of the twentieth century electric strikes were, and most still are, designed without consideration for this factor. Instead they are designed for burglary resistance and durability.

VD6211

Von Duprin 6211 Electric Strike

Click on  the dimensional diagram of the Von Duprin 6211 electric strike at right.   You can see that its total depth is 1-11/16 inches. All of its internal parts are heavy duty, and it has a heavy cast body and a thick, finished face plate. Most of the parts are individually replaceable. To install the 6211 in a hollow metal door frame, the dust box must be removed and often material inside the door frame – sheet rock, wood, masonry, whatever – must be removed in order to accommodate the strike. If the strike must be installed in a grouted door frame the installer is in for perhaps an hour’s worth of work that may involve a masonry drill, a 2-1/2 lb. sledge hammer, a masonry chisel and safety goggles.

HES 5000 Dimensional DrawingsIn more recent years a new generation of low profile (shallow depth) electric strikes has become available, offering unprecedented ease of installation. The HES 5000 (illustration at left) was one of the first strikes on the scene to offer a depth of only 1-1/16 inches, and advertised that it could be installed without even removing the dust box from the frame. I have found it is usually much easier to knock out the dust box for wiring reasons, but it is true that the unit will fit neatly inside most original equipment dust boxes in hollow metal frames.

More recent offerings in the shallow depth electric strike department include the Trine 3478, the HES 8000 and the Adams Rite 7440, illustrations shown at the end of this article.  All are UL Listed burglary resistant. The HES 8000 offers 1500 lbs. holding force, the 3478 offers 1200 lbs. holding force and the Adams Rite, with its innovative double keeper design, offers 2400 lbs. of holding force.  The Trine 3478 offers an install with a very tiny lip cutout, and the HES 8000 offers the advantage of needing no lip cutout at all. Each of them fit in a strike cavity only 1-1/16 inches deep.

These strikes have revolutionized electric strike installation. Before, a good installer might install six or ten electric strikes in a day. Now a really fast installer might be able to install 20 or more, greatly reducing labor and other costs associated with installation.

What’s the Trade-Off?

None of the internal parts of these strikes are available. When these strikes break, you throw them away and buy new ones. Also they do not last as long. Whereas it is not unusual to see a Von Duprin 6211 or a Folger Adam 712 still in use after 10 or even 20 years, 6 years of service is a long time for a low profile strike. In ten years you might be replacing a spring or solenoid in a Von Duprin, but you might be installing your second or third low profile strike in the same door frame in that same amount of time. This is a small inconvenience.

Upon installing that third strike in the same hole, you probably will not yet have equaled the price of a single Folger Adam 712 or Von Duprin 6211. If price up front is the primary consideration, low profile is definitely the way to go. But if in about 12 years you are installing the fourth replacement strike in the same prep, those expensive, harder-to-install, heavy duty strikes start to look like a much better value.

strikethree

HES model 8000, Trine model 3478 and Adams Rite model 7440

Thank you.

Locks and Keys Grow Old Together

oldkeynewkyI 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.

Radius Corner Hinges

Colloquially known as round corner hinges, radius corner hinges are used mainly on residential doors but also in some commercial applications. In the United States radius corner hinges come in two curvatures: ¼-inch radius and 5/8-inch radius. The difference is easy to see when the different radius hinges are side by side as shown below.

Radius Corner Hinges

 

They are called radius corner because their degree of curvature is determined by the length of the radius of an imaginary circle.  The ¼-inch radius corner is based on the radius of a ½-inch diameter imaginary circle and the 5/8-inch radius corner is based on the radius of a 1-1/4-inch diameter circle as shown in the following illustration:

radii

 

When we superimpose the imaginary circles onto hinges we see how the length of the radius affects the curvature:

radii1

 

In these examples I show 4-1/2 inch x 4-1/2 inch ball bearing full mortise hinges.

For more about hinges, click here.  

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