Follow lauxmyth on Twitter

Thursday, March 25, 2010

Its called "Key Attitude."

When a customer today laughed at this term, I knew it was a good item for the blog. Key attitude.

Lets start with a question. Have you ever had a lock you could unlock with your key but somebody else could not? You knew exactly how to hold the key ... how much to lift it ... how much to pull it back ... how hard to turn it ... how to comb your hair just right. You would insert the key and do a little dance with the key and you could get it to work every time. Good for you but that is NOT how a lock should work.

The engineering design is that a key should be inserted fully into a lock and you can let go of it. The springs in the lock and gravity will find a neutral place of rest for the key. Then you turn it without pulling it out or lifting it or tipping it. That is the ideal and lets put that in our rear-view mirror right now.

When you have to hold a key in some special way, it is called key attitude and it can arise for several reasons. Often the regular user of the lock has lived with a little of it for years as the key and lock wore out together so has learned the exact attitude for that key and lock. When that person passes the key to me, I find it almost impossible to work the lock. (I only hope I am entertaining as I struggle to get this key to work.)

Perhaps I should get more technical. A key fits into a lock in a keyway and the keyway always has to be a bit larger than the key. Some keys fit very exactly into the space given and really do not wiggle inside the lock more than a few thousandths of an inch. Generally these are new cylinders of the top grades of lock. As you look at more worn locks or less machined locks, the key has more air around it when in the lock and you can move the key up, down and sideways.

I guess I should say what exactly holds the key in place. Well, that depends on the lock. For the deadbolt in a house, the key should rest on the bottom of the keyway and the grooves on the side of the key should have matching ridges inside the lock to fit into them but not lift the key off the bottom of the keyway.* If the key is double sided like many cars, then usually you have springs from half the cuts pushing the key up and the other half pushing the key down. All you need to do is put 20 other keys, a cell phone, a collection of charms, a name tag and a small flashlight on your ring of keys and it will weigh enough to pull that double sided key out of the centre of the lock.

Since the fit of the key in the keyway is never exact, what attitudes are possible? Often you can lift the whole key if all the cuts on the key are too low. Also, the copy of the key can be tipped in either direction and sometimes to get it to work, you rock the tip of the key up and keep the shoulder area all the way down. Alternately, you can lift at the shoulder and keep the tip fully down. Am I done??

No. Keys are often duplicated with the blank not aligned correctly left to right in the machine. If the original is out of place, the cuts on the new key are too close to the shoulder and by the time you fully insert that key, the cuts have not yet reached where they should to operate. This key is taken back for a refund. More commonly, the copy is away from the shoulder when duplicated and this key will work if you pull it just a bit out of the lock. "Just a bit" is a precise way of saying guess and test.

And there can be one more problem but it is quite rare. When you wear a lock out, the keyway goes wide and the key can rotate slightly INSIDE the keyway before you start to turn the lock. For some keys, this rotates the cuts on the key blade out from under the pins and the pins move down and lock up the cylinder. This only happens in one direction or the other. However, if it happen when you turn the key clockwise and that is the direction which unlocks this lock, then it may seem like the key is wrong.**

(I will leave it as a homework exercise to find a solution to unlock such a lock without damage. Just had to say that. Old habits and all.)

Well, maybe this explains why it takes time to try out all the possible holding positions of a key before you find the exact key attitude to unlock it just once.

The job site which made me think of the topic was working with some safety deposit box locks. The client had keys labelled as working. One would work infrequently but a few others could not get the boxes to open at all. Safety deposit locks are not forgiving a poorly cut key and usually do not get high usage. If the key is wrong you hit a wall. I took the keys and tried a variety of attitudes with each until I had the boxes open. (Still faster and cheaper than drilling the door or destroying the lock which are the next options.) Once back in the shop, you can see where to correct the key by seeing what the internal parts are doing as you turn this key.

Do I like key attitude? Sure, it makes the job fun. Should you? A little is fine but do not make a copy of that key or you are likely to get a worse key which takes even more playing each time to open the lock. Also, most of the time poor key attitude is wearing out your lock faster than a correctly cut key. The key is generally a few dollars and can be replaced as needed without tools. The lock takes more time, money and skills to replace. Replace the key to preserve the lock seems good advice.



* I should get a prize for dodging the jargon of the trade. The grooves on the sides of keys are called millings and the shape of the hole used as a keyway is called the broaching.

** In a career as a locksmith, you will be given keys by ernest and honest customers who confidently tell you this is THE key for that lock. Later you open the lock to see the pins and it is not even close. This raises some customer service points I will discuss in some other post.


--- --- --- --- ---
The contents of this post are released for non-profit or educational use in whole or in part provided this statement and the attribution below are kept attached.

Laux Myth ... Thoughts From a Locksmith
By MartinB, Found @ http://lauxmyth.blogspot.com/

No comments:

Post a Comment