Two symbiotic ideas:

First: A consumer doorknob with a lock where the combination (that is, the profile of the key) for the lock can be changed.

A currently valid key would need to be inserted in a key slot on the interior knob. Since the operator is "inside" and has a valid key, the assembly allows the combination to be changed. The analog action of the peaks and valleys settings means there are an infinite number of combinations to choose from.

Once the formerly valid key is removed, the setting is fixed and the lock will only operate with a key that fits it.

...Where do you get a key that fits the new profile?...

Second: A consumer doorknob where the interior doorknob can be set to cut a key. The profile of the cut key is determined by the current setting of the lock. That is, the key is cut to work the exterior lock.

The turning action of the doorknob in cutting mode moves diamond-tipped cutters back and forth over your existing key or key blank. It does take effort an patience, but in time you're rewarded with a key that fits your personal lock. Cutting time can be reduced by using your previous key and only cutting new valleys.

Now you don't have to worry if your ex has a key or if you lose your key ring. Scurry on home (stopping by the hardware store for blanks), change the lock profile and cut yourself a new set of keys!
-- phoenix, Oct 07 2003

computerized lock http://www.halfbake...computerized_20lock
related idea by [jutta] [krelnik, Oct 05 2004]

Then your ex comes over, breaks a window to get inside, and locks you out of your own house.
-- krelnik, Oct 07 2003


This key-lock scheme probably has many novel applications. I can't think of any right now, but there must be a solution here for anything from rental cars to high security vaults.
-- Worldgineer, Oct 07 2003


whatever it is you are taking, I want some.

if I have to choose I prefer the first. genius!
-- po, Oct 08 2003


Yeah, this is another solution in search of a problem. Pretty halfbaked though.
-- phoenix, Oct 08 2003


How about this for inner workings. All you'd have to do is make the inside key with grooves in the opposite direction of the outside key (high lump close in on #1 = high lump far out on key #2). The inside key would be inserted upside down. Pins on the inside key are welded to little tubes each with an inner diameter of a pin. The tubes serve the function of the normal core instead of lining up to make a cylinder.

(re-reads idea and realizes he has completely misunderstood [px]'s idea)

Never mind. I'm going to post a new idea.
-- Worldgineer, Oct 08 2003


Would this be similar to a system used on cars where every time the car is started it changes a number stored on both the car and the key, if the number in the key is different to the one stored in the car, the car wont start.

Basically a key that changes every time you use it.
-- andrew1, Sep 27 2005


You enter by same window, and un-lock yourself out.
-- Darkelfan, Nov 23 2005



random, halfbakery