Locksmiths: key teeth up or down?

We had our front door replaced a while ago, and just recently I’ve noticed that the locks on the door itself are “upside down” compared to how I’d always seen locks diagrammed. The flat part of the key is on the bottom of the lock, and the teeth go up. On the older screen door, the teeth point down as you insert the key. I’ve asked around and heard that the teeth should be “up” to prevent grit, dirt, and other crap from falling into the springs and jamming the workings of the lock, but I ask the Millions for more opinions.

Is this a new way of installing locks? Have I been oblivious to changing fads in locksmithery? Maybe just the locks on my door were installed upside down by mistake?

As a former maintenance geek with a property management firm I’d say, “Every locksmith we dealt with said to install with teeth facing up and pins facing down,” for the reasons which have been mentioned to you.

As a former carpenter doing door installs I’d say, “Whichever way the homeowner prefers.” I would always, of course, mention the reasons for installing teeth up.

should be easy to take it apart and reverse the orientation. However, it probably doesn’t make a huge amount of difference either way.

From what basis of knowledge do you claim that it makes no great amount of difference? :confused:

Dirt and moisture tend to behave in a predictable manner, and gravity is a constant, such that pin chambers should always be oriented upward, e.g. teeth of the key pointing up when inserted in the lock.

Regarding the claim that reverse of orientation is a simple task, can you define ‘simple’? Some lock manufacturers products require an operating key and an icepick, yet with others, special tools which qualify as restricted to persons in the trade of locksmithing are needed.

Please advise if there is something I’ve missed in 20+ years of safe/vault/lock service.

If the lock works with less crap buildup when the teeth are pointing up, why are most locks (or is it just me?) the other direction?

A basis of knowlege obviously less expansive than your own. However, given the number of “upside down” locks I’ve encountered in my life, the fact that most door locks are not exposed to a great deal of water and/or dirt, and the fact that none of these “upside down” locks have yet failed due to being upside down, I come to the conclusion that this is not something to lose sleep over. I didn’t mean to denigrate locksmithdom in any way, although now that you mention it I’ve never come across a locksmith who really impressed me with his technical knowlege or skill. As the old saying goes, it’s not exactly rocket science.

Is it not true that most consumer-grade doorknob/lock mechanisms are designed to be installed “either way”? In my limited experience, this is true. Therefore, I’d expect the OP’s lock to be similar. Please correct me if I’m wrong.

Hey dances with cats I am glad another locksmith is here on the board.
If your ever up to moving to North Alabama we are hiring :slight_smile:

Anyway off to the OP:

Your screen door lock is most likely a wafer style lockset being mounted upside down is no big deal since wafer lock springs function a bit different.

Knob locks and deadbolts are another matter. With the sping and pin on the bottom (key teeth facing down) over time debris does get into the lock, this is not a major problem that will make the lock fail overnight. Also, the spring s will start to compress not pushing the pins up all the way up. When this happens the lock starts to fail.
From person observation an upside down lock will fail on average 3 years earlier than a normal residential lockset. (they usually last on average 10 years)

Why are they mounted up sidedown? While many locks are universal in their handing (left or right handed door) such as weiser and schlage Some locks such as quickset and titan locksets are pre mounted. They do require a special tool to remove the cyl housing and putting them in right side up.
Commercial key and know sets are also handed. They can be corrected with a key and an icepick and knowing how to do it, some contractors really do not care or do not know how to change this.

Having the lock upside down in my opinion is bad… but not such a horrible thing that you should be losing sleep over it.

I always install locks with the key cuts up. That is the proper way of doing it, from my locksmith training courses anyway. Exterior locks tend to get dirt buildup, and especially here in the frozen north moisture builds up and would tend to freeze the pins in the winter if the pins would be on the bottom. Also, the springs would wear out quicker.
ALOA# 42647

Ive installed hundreds of locksets in entry doors. In only one case it was because the pins failed. The orentation of the pins was about 50/50.

At first I just shot in some graphite lube and it cured the problem for about a month. Finally the owner just ponyed up for a new lock. Actually we changed out four, two knobs and two dead bolts so the same key would open everything.

In almost all other cases it was some other mechanical falure inside that prevented the knob from drawing back the bolt. That or the owner wanted a new style of knob.

As to the OP I am going to go ahead and step on the toes of the pros here and say it dont make a damn bit of difference. A good quality lock is going to hold up really well either way.

I am pretty convinced that the reason the pros’ do it pins up is because “thats how a pro does it”. This is no trivial matter, for the reasons stated there is a theroretical advantage to doing it that way. A true professional takes their craft seriously and does everything right to the last detail.

For gods sake, when I install a outlet or switchplate cover the screw slots both HAVE to be perfectly vertical. It’s not because I am anal, really it isn’t, no really. That’s just how a pro does it.

On our front door the deadbolt is teeth down, the handle lock is teeth up. They take the same key.

Is there a reason for this or just quirky?

The reason is because a locksmith didn’t install em. Prolly just a lowly hanyman or building contractor. Funny thing is Ive noticed this as well. deadbolts are up and doorknobs are down. Well sometimes it’s reversed, like I said before don’t get in panic over it, it will likely have NO impact on your life.

Okay, I’m convinced that there’s no harm in having the lock pins on the top. Thanks!

Here’s a somewhat related question: Why does this seem strange to me? That is, why does my usual mental image of a lock feature the teeth facing down? Perhaps I’m just crazy.

The simple cartoony “key and keyhole” combination of the single rod with two prongs (key) and the circular hole with a triangular cutout beneath it (hole) go together, but they’re a different kind of lock than the pins used today. Did the convention of teeth facing down stem from this old style lock, and when did it become “professional standard” to have the teeth upwards?

Why does it seem strange to you? my guess? because it is not what you are used to. Just as a crapper flushing in reverse when you change hemispheres seems a bit strange the first few times.

When the professional standard come about? hard to say. Linus Yale patented the modern pin tumbler lock in 1868. Not much has changed in basic design since then, except quality control. Originally materials and consistancy made the springs fail on a greater rate when mounted upside down in the beginning. Today, springs fail less and therefore, having a lock mounted upside down is less of a liability.


Actually, they don’t do that.


Thank God for small mercies. I have been postponing a trip to the Antipodes because I was concerned that the toilets would expel water rather than draining it away! :smiley:

I stand corrected.

thankfully I am a locksmith not a plumber.

Most people that I see like having the keys facing up, not because of build-up, but because it’s what they’re used to.

It seems that whether it is a left or right-handed door would have something to do with it. Now, I don’t install the locks but I do re-key them and except for the levers I never thought about right or left handed doors.

One customer came in and wanted the teeth facing up; he had three Kwikset locks , each with a mark on them. But the marks were in different places, meaning that in two of them I had to put the cylinder “backwards” or “upside” to the third one (knobs, not levers).

The deadbolt has upward facing teeth and the entry lock has downward, both Schlage. Is there ant literature on how to reverse this?

Most door locks I come across these days don’t have ‘teeth’ at all. They have grooved on a flat blade. We have five front door keys in the safe and none have teeth. The safe has buttons.

I have a related question.
The button to lock a door knob. I think that it should be that when it is locked, the rib on the button should be horizontal. But it does not seem to be universal. I have this fanciful notion that the orientation of that rib is meant to represent a barred or unbarred door, in miniature. Is there any substance to my notion?